Genome design of hybrid potato

Transcriptomic profiles reveal hormonal regulation of sugar-induced stolon initiation in potato

Potato (Solanum tuberosum L.) is one of the world's most important non-cereal food crops, with stolon development playing a crucial role in determining tuber yield. While some studies have examined the effects of sugars on potato stolon growth, their influence-particularly that of sucrose-on early stolon development remains unclear. Furthermore, the regulatory role of plant hormones in this process has yet to be established. Using a combination of in vitro culture, transcriptomics, gene expression analysis, and biochemical approaches, we investigated the contribution of sucrose (3% or 8%) on potato seedling stem nodes and stolon initials through phenotypic observation, RNA sequencing (RNA-seq), comparison of expression patterns, and hormone quantification. Firstly, compared to other types of sugars, we found that high concentrations of sucrose were the most effective in inducing stolon initial formation in potato seedlings. Furthermore, RNA-seq data showed that high sucrose levels significantly up-regulated the expression of genes involved in sugar metabolism and plant hormone metabolism. Additionally, the development of stem nodes and stolon initials under high sucrose conditions was also closely linked to hormone metabolism. Notably, high sucrose concentrations contributed to stem node and stolon initial development by modulating the IAA, CK, and GA signaling pathways. Based on the endogenous hormone measurement, and exogenous hormone application, together with heterologous overexpression of a potato Auxin response factor 9 (StARF9), we concluded that the early development of potato stolons was regulated by plant hormones, particularly auxin. In summary, this study elucidates the hormonal regulation of stolon initiation under high sucrose concentrations, offering a theoretical foundation and potential targets for in vitro culture and genetic improvement of potato.

Integrating Arabidopsis and crop species gene discovery for crop improvement

Genome sequence assemblies form a durable and precise framework supporting nearly all areas of biological research, including evolutionary biology, taxonomy and conservation science, pathogen population diversity, crop domestication, and biochemistry. In the early days of plant genomics, resources were limited to a handful of tractable genomes, leading to a tension between focus on discovering mechanisms in experimental species such as Arabidopsis thaliana (Arabidopsis) and on trait analyses in crop species. This tension arose from challenges in translating knowledge of gene function across the large evolutionary distances between Arabidopsis and diverse crop species in the absence of comparative genome support. For some time, these clashing interests influenced funding priorities in plant science that limited both the acquisition of knowledge of mechanisms in Arabidopsis and the timely development of the capacity of crop science to incorporate emerging knowledge of genes and their mechanisms. In this review we show how advances in genomics analysis technologies are revealing a high degree of conservation of molecular mechanisms between evolutionarily distant plant species. This progress is bridging the model-species-to-crop barrier, resulting in ever-increasing unification of plant science that is now accelerating progress in understanding mechanisms underlying diverse traits in crops and improving their performance. We lay out some examples of important priorities and outcomes arising from these new opportunities.

Origin of a self-compatibility associated MITE in Petota and its application in hybrid potato breeding

Hybrid potato breeding offers a promising solution to tackle the challenges in potato breeding. However, most diploids are self-incompatible (SI), which hinders the development of inbred lines. S-locus inhibitor (Sli) is a 'master key' gene capable of conferring self-compatibility (SC) to most of the SI diploids, yet the regulatory mechanism underlying its male gamete-specific expression remains unclear, limiting its breeding potential. This study has uncovered that a miniature inverted-repeat transposable element (Mi-549) within the Sli promoter can affect the methylation pattern of the promoter, thereby regulating the pollen-specific expression of Sli as well as the SC phenotype in diploids. We delved into the origin of Mi-549 within Petota and found that Mi-549 was likely acquired fortuitously in wild Solanum lesteri but was not favored during domestication, probably due to the asexual propagation nature of potato. Although Mi-549 and its impacts on Sli as well as SC are not selected, screening of Mi-549 identified three novel SC accessions that belong to S. lesteri, Solanum neocardenasii and Solanum stenotomum, which enrich the germplasm pool associated with stress and pest resistance and hold significant value for breeding applications.

Rational Redomestication for Future Agriculture

Modern agricultural practices rely on high-input, intensive cultivation of a few crop varieties with limited diversity, increasing the vulnerability of our agricultural systems to biotic and abiotic stresses and the effects of climate changes. This necessitates a paradigm shift toward a more sustainable agricultural model to ensure a stable and dependable food supply for the burgeoning global population. Leveraging knowledge from crop biology, genetics, and genomics, alongside state-of-the-art biotechnologies, rational redomestication has emerged as a targeted and knowledge-driven approach to crop innovation. This strategy aims to broaden the range of species available for agriculture, restore lost genetic diversity, and further improve existing domesticated crops. We summarize how diverse plants can be exploited in rational redomestication endeavors, including wild species, underutilized plants, and domesticated crops. Equipped with rational redomestication approaches, we propose different strategies to empower the fast and slow breeding systems distinguished by plant reproduction systems.

The phased pan-genome of tetraploid European potato

Potatoes were first brought to Europe in the sixteenth century1,2. Two hundred years later, one of the species had become one of the most important food sources across the entire continent and, later, even the entire world3. However, its highly heterozygous, autotetraploid genome has complicated its improvement since then4-7. Here we present the pan-genome of European potatoes generated from phased genome assemblies of ten historical potato cultivars, which includes approximately 85% of all haplotypes segregating in Europe. Sequence diversity between the haplotypes was extremely high (for example, 20× higher than in humans), owing to numerous introgressions from wild potato species. By contrast, haplotype diversity was very low, in agreement with the population bottlenecks caused by domestication and transition to Europe. To illustrate a practical application of the pan-genome, we converted it into a haplotype graph and used it to generate phased, megabase-scale pseudo-genome assemblies of commercial potatoes (including the famous French fries potato 'Russet Burbank') using cost-efficient short reads only. In summary, we present a nearly complete pan-genome of autotetraploid European potato, we describe extraordinarily high sequence diversity in a domesticated crop, and we outline how this resource might be used to accelerate genomics-assisted breeding and research.

A genomic variation map provides insights into potato evolution and key agronomic traits

Hybrid potato breeding based on diploid inbred lines is transforming the way of genetic improvement of this staple food crop, which requires a deep understanding of potato domestication and differentiation. In the present study, we resequenced 314 diploid wild and landrace accessions to generate a variome map of 47,203,407 variants. Using the variome map, we discovered the reshaping of tuber transcriptome during potato domestication, characterized genome-wide differentiation between landrace groups Stenotomum and Phureja. We identified a jasmonic acid biosynthetic gene possibly affecting the tuber dormancy period. Genome-wide association studies revealed a UDP-glycosyltransferase gene for the biosynthesis of anti-nutritional steroidal glycoalkaloids (SGAs), and a Dehydration Responsive Element Binding (DREB) transcription factor conferring increased average tuber weight. In addition, genome similarity and group-specific SNP analyses indicated that tetraploid potatoes originated from the diploid Solanum tuberosum group Stenotomum. These findings shed light on the evolutionary trajectory of potato domestication and improvement, providing a solid foundation for advancing hybrid potato-breeding practices.

A comprehensive all-in-one CRISPR toolbox for large-scale screens in plants

Clustered regularly interspaced short palindromic repeats (CRISPR)-associated nuclease (Cas) technologies facilitate routine genome engineering of one or a few genes at a time. However, large-scale CRISPR screens with guide RNA libraries remain challenging in plants. Here, we have developed a comprehensive all-in-one CRISPR toolbox for Cas9-based genome editing, cytosine base editing, adenine base editing (ABE), Cas12a-based genome editing and ABE, and CRISPR-Act3.0-based gene activation in both monocot and dicot plants. We evaluated all-in-one T-DNA expression vectors in rice (Oryza sativa, monocot) and tomato (Solanum lycopersicum, dicot) protoplasts, demonstrating their broad and reliable applicability. To showcase the applications of these vectors in CRISPR screens, we constructed guide RNA (gRNA) pools for testing in rice protoplasts, establishing a high-throughput approach to select high-activity gRNAs. Additionally, we demonstrated the efficacy of sgRNA library screening for targeted mutagenesis of ACETOLACTATE SYNTHASE in rice, recovering novel candidate alleles for herbicide resistance. Furthermore, we carried out a CRISPR activation screen in Arabidopsis thaliana, rapidly identifying potent gRNAs for FLOWERING LOCUS T activation that confer an early-flowering phenotype. This toolbox contains 61 versatile all-in-one vectors encompassing nearly all commonly used CRISPR technologies. It will facilitate large-scale genetic screens for loss-of-function or gain-of-function studies, presenting numerous promising applications in plants.

Leveraging a phased pangenome for haplotype design of hybrid potato

The tetraploid genome and clonal propagation of the cultivated potato (Solanum tuberosum L.)1,2 dictate a slow, non-accumulative breeding mode of the most important tuber crop. Transitioning potato breeding to a seed-propagated hybrid system based on diploid inbred lines has the potential to greatly accelerate its improvement3. Crucially, the development of inbred lines is impeded by manifold deleterious variants; explaining their nature and finding ways to eliminate them is the current focus of hybrid potato research4-10. However, most published diploid potato genomes are unphased, concealing crucial information on haplotype diversity and heterozygosity11-13. Here we develop a phased potato pangenome graph of 60 haplotypes from cultivated diploids and the ancestral wild species, and find evidence for the prevalence of transposable elements in generating structural variants. Compared with the linear reference, the graph pangenome represents a broader diversity (3,076 Mb versus 742 Mb). Notably, we observe enhanced heterozygosity in cultivated diploids compared with wild ones (14.0% versus 9.5%), indicating extensive hybridization during potato domestication. Using conservative criteria, we identify 19,625 putatively deleterious structural variants (dSVs) and reveal a biased accumulation of deleterious single nucleotide polymorphisms (dSNPs) around dSVs in coupling phase. Based on the graph pangenome, we computationally design ideal potato haplotypes with minimal dSNPs and dSVs. These advances provide critical insights into the genomic basis of clonal propagation and will guide breeders to develop a suite of promising inbred lines.

Time-course dual RNA-seq analyses and gene identification during early stages of plant-Phytophthora infestans interactions

Late blight caused by Phytophthora infestans is a major threat to global potato and tomato production. Sustainable management of late blight requires the development of resistant crop cultivars. This process can be facilitated by high-throughput identification of functional genes involved in late blight pathogenesis. In this study, we generated a high-quality transcriptomic time-course dataset focusing on the initial 24 h of contact between P. infestans and 3 solanaceous plant species, tobacco (Nicotiana benthamiana), tomato (Solanum lycopersicum), and potato (Solanum tuberosum). Our results demonstrate species-specific transcriptional regulation in early stages of the infection. Transient silencing of putative RIBOSE-5-PHOSPHATE ISOMERASE and HMG-CoA REDUCTASE genes in N. benthamiana lowered plant resistance against P. infestans. Furthermore, heterologous expression of a putative tomato Golgi-localized nucleosugar transporter-encoding gene exacerbated P. infestans infection of N. benthamiana. In comparison, bioassays using transgenic tomato lines showed that the quantitative disease resistance genes were required but insufficient for late blight resistance; genetic knock-out of the susceptibility gene enhanced resistance. The same RNA-seq dataset was exploited to examine the transcriptional landscape of P. infestans and revealed host-specific gene expression patterns in the pathogen. This temporal transcriptomic diversity, in combination with genomic distribution features, identified the P. infestans IPI-B family GLYCINE-RICH PROTEINs as putative virulence factors that promoted disease severity or induced plant tissue necrosis when transiently expressed in N. benthamiana. These functional genes underline the effectiveness of functional gene-mining through a time-course dual RNA-seq approach and provide insight into the molecular interactions between solanaceous plants and P. infestans.

Impacts of reproductive systems on grapevine genome and breeding

Diversified reproductive systems can be observed in the plant kingdom and applied in crop breeding; however, their impacts on crop genomic variation and breeding remain unclear. Grapevine (Vitis vinifera L.), a widely planted fruit tree, underwent a shift from dioecism to monoecism during domestication and involves crossing, self-pollination, and clonal propagation for its cultivation. In this study, we discover that the reproductive types, namely, crossing, selfing, and cloning, dramatically impact genomic landscapes and grapevine breeding based on comparative genomic and population genetics of wild grapevine and a complex pedigree of Pinot Noir. The impacts are widely divergent, which show interesting patterns of genomic purging and the Hill-Robertson interference. Selfing reduces genomic heterozygosity, while cloning increases it, resulting in a "double U-shaped" site frequency spectrum (SFS). Crossing and cloning conceal while selfing purges most deleterious and structural burdens. Moreover, the close leakage of large-effect deleterious and structural variations in repulsion phases maintains heterozygous genomic regions in 4.3% of the grapevine genome after successive selfing for nine generations. Our study provides new insights into the genetic basis of clonal propagation and genomic breeding of clonal crops by purging deleterious variants while integrating beneficial variants through various reproductive systems.

Towards Stewardship of Wild Species and Their Domesticated Counterparts: A Case Study in Northern Wild Rice (Zizania palustris L.)

Northern Wild Rice (NWR; Zizania palustris L.) is an aquatic, annual grass with significant ecological, cultural, and economic importance to the Great Lakes region of North America. In this study, we assembled and genotyped a diverse collection of 839 NWR individuals using genotyping-by-sequencing (GBS) and obtained 5955 single-nucleotide polymorphisms (SNPs). This collection consisted of samples from 12 wild NWR populations collected across Minnesota and Western Wisconsin, some of which were collected over two time points; a representative collection of cultivated NWR varieties and breeding populations; and a Zizania aquatica outgroup. Using these data, we characterized the genetic diversity, relatedness, and population structure of this broad collection of NWR genotypes. We found that wild populations of NWR clustered primarily by their geographical location, with some clustering patterns likely influenced by historical ecosystem management. Cultivated populations were genetically distinct from wild populations, suggesting limited gene flow between the semi-domesticated crop and its wild counterparts. The first genome-wide scans of putative selection events in cultivated NWR suggest that the crop is undergoing heavy selection pressure for traits conducive to irrigated paddy conditions. Overall, this study presents a large set of SNP markers for use in NWR genetic studies and provides new insights into the gene flow, history, and complexity of wild and cultivated populations of NWR.

Origin and de novo domestication of sweet orange

Sweet orange is cultivated worldwide but suffers from various devastating diseases because of its monogenetic background. The elucidation of the origin of a crop facilitates the domestication of new crops that may better cope with new challenges. Here we collected and sequenced 226 citrus accessions and assembled telomere-to-telomere phased diploid genomes of sweet orange and sour orange. On the basis of a high-resolution haplotype-resolved genome analysis, we inferred that sweet orange originated from a sour orange × mandarin cross and confirmed this model using artificial hybridization experiments. We identified defense-related metabolites that potently inhibited the growth of multiple industrially important pathogenic bacteria. We introduced diversity to sweet orange, which showed wide segregation in fruit flavor and disease resistance and produced canker-resistant sweet orange by selecting defense-related metabolites. Our findings elucidate the origin of sweet orange and de novo domesticated disease-resistant sweet oranges, illuminating a strategy for the rapid domestication of perennial crops.

Polymerization of beneficial plant height QTLs to develop superior lines which can achieving hybrid performance levels

Heterosis, a key technology in modern commercial maize breeding, is limited by the narrow genetic base which hinders breeders from developing superior hybrid varieties. By integrating big data and functional genomics technologies, it becomes possible to create new super maize inbred lines that resemble hybrid varieties through the aggregation of multiple QTL parental advantage loci. In this study, we utilized a combination of resequencing and field selfing selection methods to develop three pyramiding QTL lines (PQLs) (PQL4, 6, and 7), each containing 15, 12, and 12 QTL loci respectively. Among the three PQLs, PQL6 (266.78 cm/119.39 cm) demonstrated hybrid-like performance comparable to the hybrid (276.96 cm/127.02 cm) (P < 0.05). Testcross between PQL6 and the parental lines revealed that PQL6 had accumulated and fixed advanced parent alleles for superior traits in plant and ear height. The significant increase in PQL6 plant height primarily resulted from the aggregation of two major effective QTL (qEH2-1 and qEH8-1 on chromosomes 2 and 8), indicating that the aggregation of major effective QTL is a key selection indicator. Furthermore, PQL6 exhibited slow vegetative growth but experienced a rapid height increase during the reproductive stage, particularly in the 1-2 weeks before flowering, when its growth rate accelerated and surpassed that of the hybrid varieties. Our study explored the time period and key parameter indicators for molecular breeding of maize, providing a theoretical concept and practices for further complex multi-trait design and aggregation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11032-025-01546-4.

To infinity and beyond: recent progress, bottlenecks, and potential of clonal seeds by apomixis

Apomixis - clonal seed production in plants - is a rare yet phylogenetically widespread trait that has recurrently evolved in plants to fix hybrid genotypes over generations. Apomixis is absent from major crop species and has been seen as a holy grail of plant breeding due to its potential to propagate hybrid vigor in perpetuity. Here we exhaustively review recent progress, bottlenecks, and potential in the individual components of gametophytic apomixis (avoidance of meiosis, skipping fertilization by parthenogenesis, autonomous endosperm development), and sporophytic apomixis. The Mitosis instead of Meiosis system has now been successfully set up in three species (Arabidopsis, rice, and tomato), yet significant hurdles remain for universal bioengineering of clonal gametes. Parthenogenesis has been engineered in even more species, yet incomplete penetrance still remains an issue; we discuss the choice of parthenogenesis genes (BABY BOOM, PARTHENOGENESIS, WUSCHEL) and also how to drive egg cell-specific expression. The identification of pathways to engineer autonomous endosperm development would allow fully autonomous seed production, yet here significant challenges remain. The recent achievements in the engineering of synthetic apomixis in rice at high penetrance show great potential and the remaining obstacles toward implementation in this crop are addressed. Overall, the recent practical examples of synthetic apomixis suggest the field is flourishing and implementation in agricultural systems could soon take place.

Carotenoids in Potato Tubers: A Bright Yellow Future Ahead

Carotenoids, the bright yellow, orange, and red pigments of many fruits and vegetables, are essential components of the human diet as bioactive compounds not synthesized in animals. As a staple crop potato has the potential to deliver substantial amounts of these nutraceuticals despite their lower concentration in tubers compared to edible organs of other plant species. Even small gains in tuber carotenoid levels could have a significant impact on the nutritional value of potatoes. This review will focus on the current status and future perspectives of carotenoid biofortification in potato with conventional breeding and biotechnological approaches. The high biodiversity of tuber carotenoid levels and composition is presented, with an emphasis on the under-exploited native germplasm that represents a wide reservoir of useful genetic variants to breed carotenoid-rich varieties. The following section describes the structural genes involved in carotenoid metabolism and storage known to have a major impact on carotenoid accumulation in potato, together with the strategies that harnessed their expression changes to increase tuber carotenoid content. Finally, the little information available on the regulation of carotenoid metabolism and the desirable future advances in potato carotenoid biofortification are discussed.

Interspecific hybridization in Brassica species leads to changes in agronomic traits through the regulation of gene expression by chromatin accessibility and DNA methylation

Interspecific hybridization is a common method in plant breeding to combine traits from different species, resulting in allopolyploidization and significant genetic and epigenetic changes. However, our understanding of genome-wide chromatin and gene expression dynamics during allopolyploidization remains limited. This study generated two Brassica allotriploid hybrids via interspecific hybridization. We observed that accessible chromatin regions (ACRs) and DNA methylation interact to regulates gene expression after interspecific hybridization, ultimately influencing the agronomic traits of the hybrids. In total, 234,649 ACRs were identified in the parental lines and hybrids; the hybridization process induces changes in the distribution and abundance of their accessible chromatin regions, particularly in gene regions and their proximity. Genes associated with proximal ACRs were more highly expressed than those associated with distal and genic ACRs. More than half of novel ACRs drove transgressive gene expression in the hybrids, and the transgressive upregulated genes showed significant enrichment in metal ion binding, especially magnesium ion, calcium ion, and potassium ion binding. We also identified Bna.bZIP11 in the single-parent activation ACR, which binds to BnaA06.UF3GT to promote anthocyanin accumulation in F1 hybrids. DNA methylation plays a role in repressing gene expression, and unmethylated ACRs are more transcriptionally active. Additionally, the A-subgenome ACRs were associated with genome dosage rather than DNA methylation. The interplay among DNA methylation, transposable elements, and sRNA contributes to the dynamic landscape of ACRs during interspecific hybridization, resulting in distinct gene expression patterns on the genome.

Grapevine pangenome facilitates trait genetics and genomic breeding

Grapevine breeding is hindered by a limited understanding of the genetic basis of complex agronomic traits. This study constructs a graph-based pangenome reference (Grapepan v.1.0) from 18 newly generated phased telomere-to-telomere assemblies and 11 published assemblies. Using Grapepan v.1.0, we build a variation map with 9,105,787 short variations and 236,449 structural variations (SVs) from the resequencing data of 466 grapevine cultivars. Integrating SVs into a genome-wide association study, we map 148 quantitative trait loci for 29 agronomic traits (50.7% newly identified), with 12 traits significantly contributed by SVs. The estimated heritability improves by 22.78% on average when including SVs. We discovered quantitative trait locus regions under divergent artificial selection in metabolism and berry development between wine and table grapes, respectively. Moreover, significant genetic correlations were detected among the 29 traits. Under a polygenic model, we conducted genomic predictions for each trait. In general, our study facilitates the breeding of superior cultivars via the genomic selection of multiple traits.

LAZARUS 1 functions as a positive regulator of plant immunity and systemic acquired resistance

Systemic acquired resistance (SAR) is activated by local infection and confers enhanced resistance against subsequent pathogen invasion. Salicylic acid (SA) and N-hydroxypipecolic acid (NHP) are two key signaling molecules in SAR and their levels accumulate during SAR activation. Two members of plant-specific Calmodulin-Binding Protein 60 (CBP60) transcription factor family, CBP60g and SARD1, regulate the expression of biosynthetic genes of SA and NHP. CBP60g and SARD1 function as master regulators of plant immunity and their expression levels are tightly controlled. Although there are numerous reports on regulation of their expression, the specific mechanisms by which SARD1 and CBP60g respond to pathogen infection are not yet fully understood. This study identifies and characterizes the role of the LAZARUS 1 (LAZ1) and its homolog LAZ1H1 in plant immunity. A forward genetic screen was conducted in the sard1-1 mutant background to identify mutants with enhanced SAR-deficient phenotypes (sard mutants), leading to the discovery of sard6-1, which maps to the LAZ1 gene. LAZ1 and its homolog LAZ1H1 were found to be positive regulators of SAR through regulating the expression of CBP60g and SARD1 as well as biosynthetic genes of SA and NHP. Furthermore, Overexpression of LAZ1, LAZ1H1 and its homologs from Nicotiana benthamiana and potato enhanced resistance in N. benthamiana against Phytophthora pathogens. These findings indicate that LAZ1 and LAZ1H1 are evolutionarily conserved proteins that play critical roles in plant immunity.

Biofortification of potato nutrition

BACKGROUND

Potato (Solanum tuberosum L.) is the fourth most important food crop after rice, wheat and maize in the world with the potential to feed the world's population, and potato is a major staple food in many countries. Currently, potato is grown in more than 100 countries and is consumed by more than 1 billion people worldwide, and the global annual output exceeds 300 million tons. With the rapid increase in the global population, potato will play a key role in food supply. These aspects have driven scientists to genetically engineer potato for yield and nutrition improvement.

AIM OF REVIEW

Potato is an excellent source of carbohydrates, rich in vitamins, phenols and minerals. At present, the nutritional fortification of potato has made remarkable progress, and the biomass and nutrient compositions of potato have been significantly improved through agronomic operation and genetic improvement. This review aims to summarize recent advances in the nutritional fortification of potato protein, lipid and vitamin, and provides new insights for future potato research.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review comprehensively summarizes the biofortification of potato five nutrients from protein, lipid, starch, vitamin to mineral. Meanwhile, we also discuss the multilayered insights in the prospects of edible potato fruit, vaccines and high-value products synthesis, and diploid potato seeds reproduction.

Exploring CDF gene family in wild potato under salinity stress unveils promising candidates for developing climate-resilient crops

The DNA-binding with one finger (Dof) gene family is a class of plant-specific transcription factors involved in diverse biological processes, including response to biotic and abiotic stresses. Members of this family have been reported in the cultivated potato Solanum tuberosum, but clues to the roles of several Dof genes are still lacking. Potato wild relatives represent a genetic reservoir for breeding as they could provide useful alleles for adaptation to the environment and tolerance to biotic and abiotic stresses. We performed an in silico analysis to identify genes belonging to the Dof family in the wild potato S. commersonii, confirming that the identified Dof genes can be grouped in four classes (A, B, C, D), as reported for cultivated potato. A special focus was dedicated to Cycling Dof Factors (CDFs), which play a crucial role in plant responses to abiotic stresses. Analysis of available RNA-seq data confirmed CDF genes as regulated by stresses and often in a tissue specific manner. To ascertain their involvement in the stress response, S. tuberosum and S. commersonii plantlets growing in vitro were subjected to salt stress (80mM NaCl) for short (2 days) and prolonged (7 days) times. Analysis of phenotypic traits and qRT-PCR expression profiles of target CDF genes in aerial and root tissues showed differences between the two species. In addition, after saline treatment, changes in total phenols, proline, and malondialdehyde suggested a diverse perception of saline stress in S. commersonii vs. S. tuberosum. Overall, this study provided useful clues to the involvement of CDF genes in salt response and promoted the identification of potential candidate genes for further functional studies.

QTL discovery for agronomic and quality traits in diploid potato clones using PotatoMASH amplicon sequencing

We genotyped a population of 618 diploid potato clones derived from six independent potato-breeding programmes from NW-Europe. The diploids were phenotyped for 23 traits, using standardized protocols and common check varieties, enabling us to derive whole population estimators for most traits. We subsequently performed a genome-wide association study (GWAS) to identify quantitative trait loci (QTL) for all traits with SNPs and short-read haplotypes derived from read-backed phasing. In this study, we used a marker platform called PotatoMASH (Potato Multi-Allele Scanning Haplotags); a pooled multiplex amplicon sequencing based approach. Through this method, neighboring SNPs within an amplicon can be combined to generate multiallelic short-read haplotypes (haplotags) that capture recombination history between the constituent SNPs and reflect the allelic diversity of a given locus in a different way than single bi-allelic SNPs. We found a total of 37 unique QTL across both marker types. A core of 10 QTL was detected with SNPs as well as with haplotags. Haplotags allowed to detect an additional 14 QTL not found based on the SNP set. Conversely, the bi-allelic SNP set also found 13 QTL not detectable using the haplotag set. We conclude that both marker types should routinely be used in parallel to maximize the QTL detection power. We report 19 novel QTL for nine traits: Skin Smoothness, Sprout Dormancy, Total Tuber Number, Tuber Length, Yield, Chipping Color, After-cooking Blackening, Cooking Type, and Eye depth.

Integrative multi-omics analysis reveals genetic and heterotic contributions to male fertility and yield in potato

The genetic analysis of potato is hampered by the complexity of tetrasomic inheritance. An ongoing effort aims to transform the clonally propagated tetraploid potato into a seed-propagated diploid crop, which would make genetic analyses much easier owing to disomic inheritance. Here, we construct and report the large-scale genetic and heterotic characteristics of a diploid F2 potato population derived from the cross of two highly homozygous inbred lines. We investigate 20,382 traits generated from multi-omics dataset and identify 25,770 quantitative trait loci (QTLs). Coupled with gene expression data, we construct a systems-genetics network for gene discovery in potatoes. Importantly, we explore the genetic basis of heterosis in this population, especially for yield and male fertility heterosis. We find that positive heterotic effects of yield-related QTLs and negative heterotic effects of metabolite QTLs (mQTLs) contribute to yield heterosis. Additionally, we identify a PME gene with a dominance heterotic effect that plays an important role in male fertility heterosis. This study provides genetic resources for the potato community and will facilitate the application of heterosis in diploid potato breeding.

Hybrid Prediction in Horticulture Crop Breeding: Progress and Challenges

In the context of rapidly increasing population and diversified market demands, the steady improvement of yield and quality in horticultural crops has become an urgent challenge that modern breeding efforts must tackle. Heterosis, a pivotal theoretical foundation for plant breeding, facilitates the creation of superior hybrids through crossbreeding and selection among a variety of parents. However, the vast number of potential hybrids presents a significant challenge for breeders in efficiently predicting and selecting the most promising candidates. The development and refinement of effective hybrid prediction methods have long been central to research in this field. This article systematically reviews the advancements in hybrid prediction for horticultural crops, including the roles of marker-assisted breeding and genomic prediction in phenotypic forecasting. It also underscores the limitations of some predictors, like genetic distance, which do not consistently offer reliable hybrid predictions. Looking ahead, it explores the integration of phenomics with genomic prediction technologies as a means to elevate prediction accuracy within actual breeding programs.

Unlocking the mystery of heterosis opens the era of intelligent rice breeding

Heterosis refers to the phenomenon where the first filial offspring (F1) from genetically diverse parents displays advantages in growth rate, yield, and adaptability compared with its parents. The exploitation of heterosis in rice breeding has greatly increased the productivity, making a significant contribution to food security in the last half of the century. Conventional hybrid rice breeding highly relies on the breeder's experience on random crossing and comprehensive field selection. This process is time-consuming and labor-intensive. In recent years, rice hybrid breeding has encountered challenges stemming from limited germplasm resource, low breeding efficiency, and high uncertainty, which constrain the progress in yield increase, coupled with difficulties in balancing grain yield, quality, and resistance. Understanding the genetic basis of rice heterosis could lead to significant advancements in breeding concepts and methods. This will fully unleash the advantages of heterosis. In this review, we focus on the research progress of the genetic dissection of crop heterosis and briefly introduce some key advancements in modern intelligent breeding of rice hybrid.

Chromosome-scale genome assembly and annotation of the tetraploid potato cultivar Diacol Capiro adapted to the Andean region

Potato (Solanum tuberosum) is an essential crop for food security and is ranked as the third most important crop worldwide for human consumption. The Diacol Capiro cultivar holds the dominant position in Colombian cultivation, primarily catering to the food processing industry. This highly heterozygous, autotetraploid cultivar belongs to the Andigenum group and it stands out for its adaptation to a wide variety of environments spanning altitudes from 1,800 to 3,200 meters above sea level. Here, a chromosome-scale assembly, referred to as DC, is presented for this cultivar. The assembly was generated by combining circular consensus sequencing with proximity ligation Hi-C for the scaffolding and represents 2.369 Gb with 48 pseudochromosomes covering 2,091 Gb and an anchor rate of 88.26%. The reference genome metrics, including an N50 of 50.5 Mb, a BUSCO (Benchmarking Universal Single-Copy Orthologue) score of 99.38%, and an Long Terminal Repeat Assembly Index score of 13.53, collectively signal the achieved high assembly quality. A comprehensive annotation yielded a total of 154,114 genes, and the associated BUSCO score of 95.78% for the annotated sequences attests to their completeness. The number of predicted NLR (Nucleotide-Binding and Leucine-Rich-Repeat genes) was 2107 with a large representation of NBARC (for nucleotide binding domain shared by Apaf-1, certain R gene products, and CED-4) containing domains (99.85%). Further comparative analysis of the proposed annotation-based assembly with high-quality known potato genomes, showed a similar genome metrics with differences in total gene numbers related to the ploidy status. The genome assembly and annotation of DC presented in this study represent a valuable asset for comprehending potato genetics. This resource aids in targeted breeding initiatives and contributes to the creation of enhanced, resilient, and more productive potato varieties, particularly beneficial for countries in Latin America.

The brassinosteroid receptor StBRI1 promotes tuber development by enhancing plasma membrane H+-ATPase activity in potato

The brassinosteroid (BR) receptor BRASSINOSTEROID-INSENSITIVE 1 (BRI1) plays a critical role in plant growth and development. Although much is known about how BR signaling regulates growth and development in many crop species, the role of StBRI1 in regulating potato (Solanum tuberosum) tuber development is not well understood. To address this question, a series of comprehensive genetic and biochemical methods were applied in this investigation. It was determined that StBRI1 and Solanum tuberosum PLASMA MEMBRANE (PM) PROTON ATPASE2 (PHA2), a PM-localized proton ATPase, play important roles in potato tuber development. The individual overexpression of StBRI1 and PHA2 led to a 22% and 25% increase in tuber yield per plant, respectively. Consistent with the genetic evidence, in vivo interaction analysis using double transgenic lines and PM H+-ATPase activity assays indicated that StBRI1 interacts with the C-terminus of PHA2, which restrains the intramolecular interaction of the PHA2 C-terminus with the PHA2 central loop to attenuate autoinhibition of PM H+-ATPase activity, resulting in increased PHA2 activity. Furthermore, the extent of PM H+-ATPase autoinhibition involving phosphorylation-dependent mechanisms corresponds to phosphorylation of the penultimate Thr residue (Thr-951) in PHA2. These results suggest that StBRI1 phosphorylates PHA2 and enhances its activity, which subsequently promotes tuber development. Altogether, our results uncover a BR-StBRI1-PHA2 module that regulates tuber development and suggest a prospective strategy for improving tuberous crop growth and increasing yield via the cell surface-based BR signaling pathway.

Haplotype-resolved genome and mapping of freezing tolerance in the wild potato Solanum commersonii

Solanum commersonii (2n = 2x = 24, 1EBN, Endosperm Balance Number), native to the southern regions of Brazil, Uruguay, and northeastern Argentina, is the first wild potato germplasm collected by botanists and exhibits a remarkable array of traits related to disease resistance and stress tolerance. In this study, we present a high-quality haplotype-resolved genome of S. commersonii. The two identified haplotypes demonstrate chromosome sizes of 706.48 and 711.55 Mb, respectively, with corresponding chromosome anchoring rates of 94.2 and 96.9%. Additionally, the contig N50 lengths are documented at 50.87 and 45.16 Mb. The gene annotation outcomes indicate that the haplotypes encompasses a gene count of 39 799 and 40 078, respectively. The genome contiguity, completeness, and accuracy assessments collectively indicate that the current assembly has produced a high-quality genome of S. commersonii. Evolutionary analysis revealed significant positive selection acting on certain disease resistance genes, stress response genes, and environmentally adaptive genes during the evolutionary process of S. commersonii. These genes may be related to the formation of diverse and superior germplasm resources in the wild potato species S. commersonii. Furthermore, we utilized a hybrid population of S. commersonii and S. verrucosum to conduct the mapping of potato freezing tolerance genes. By combining BSA-seq analysis with traditional QTL mapping, we successfully mapped the potato freezing tolerance genes to a specific region on Chr07, spanning 1.25 Mb, with a phenotypic contribution rate of 18.81%. In short, current research provides a haplotype-resolved reference genome of the diploid wild potato species S. commersonii and establishes a foundation for further cloning and unraveling the mechanisms underlying cold tolerance in potatoes.

Complex pectin metabolism by Lactobacillus and Streptococcus suggests an effective control approach for Maillard harmful products in brown fermented milk

Harmful Maillard reaction products (HMRPs) derived from brown fermented milk pose a potential threat to human health, but the conversion mechanism during the manufacturing process remains elusive and urgently needs to be controlled. Acrylamide (FC 2.14, adjusted p-value = 0.041), 5-hydroxymethylfurfural (FC 2.61, adjusted p-value = 0.026) and methylglyoxal (FC 2.07, adjusted p-value = 0.019) were identified as the significantly increased HMRPs after browning in this study and the analysis of proteomics integrated with untargeted metabolomics demonstrated that the degradation of HMRPs was jointly accomplished by Streptococcus thermophilus and Lactobacillus bulgaricus. The galactose oligosaccharide metabolism in Streptococcus thermophilus was identified as a key biochemical reaction for HMRPs degradation, and the hydrolysates of pectin could be utilized as prebiotics for Streptococcus thermophilus. Eighteen classes of enzymes of L. bulgaricus and Streptococcus thermophilus related to energy metabolism were upregulated in the pectin-added group, indicating that the entry of acrylamide and methylglyoxal into the tricarboxylic acid cycle was accelerated. NAD-aldehyde dehydrogenase and alanine dehydrogenase are enzymes belonging to Streptococcus thermophilus, and their downregulation accelerated the efflux of acetate, which was beneficial for the proliferation of L. bulgaricus and prevented the conversion of pyruvate to l-alanine, thus facilitating the energy metabolism. The recoveries and relative standard deviations of the intraday and interday precision experiments were 89.1%-112.5%, 1.3%-8.4% and 2.1%-9.4%, respectively, indicating that the developed approach was credible. Sensory evaluation results revealed that the brown fermented milk added with pectin had a better flavor, which was due to the fact that the supplement of polysaccharide promoted the fatty acid metabolism of lactic acid bacteria and increased the aroma substances including octoic acid and valeric acid. This study provided an insight into the formation and degradation mechanism of HMRPs in brown fermented milk, aiming to reduce the intake of advanced glycation end products in the diet.

Potato: from functional genomics to genetic improvement

Potato is the most widely grown non-grain crop and ranks as the third most significant global food crop following rice and wheat. Despite its long history of cultivation over vast areas, slow breeding progress and environmental stress have led to a scarcity of high-yielding potato varieties. Enhancing the quality and yield of potato tubers remains the ultimate objective of potato breeding. However, conventional breeding has faced challenges due to tetrasomic inheritance, high genomic heterozygosity, and inbreeding depression. Recent advancements in molecular biology and functional genomic studies of potato have provided valuable insights into the regulatory network of physiological processes and facilitated trait improvement. In this review, we present a summary of identified factors and genes governing potato growth and development, along with progress in potato genomics and the adoption of new breeding technologies for improvement. Additionally, we explore the opportunities and challenges in potato improvement, offering insights into future avenues for potato research.

Graph-Based Pan-Genome Reveals the Pattern of Deleterious Mutations during the Domestication of Saccharomyces cerevisiae

The "cost of domestication" hypothesis suggests that the domestication of wild species increases the number, frequency, and/or proportion of deleterious genetic variants, potentially reducing their fitness in the wild. While extensively studied in domesticated species, this phenomenon remains understudied in fungi. Here, we used Saccharomyces cerevisiae, the world's oldest domesticated fungus, as a model to investigate the genomic characteristics of deleterious variants arising from fungal domestication. Employing a graph-based pan-genome approach, we identified 1,297,761 single nucleotide polymorphisms (SNPs), 278,147 insertion/deletion events (indels; <30 bp), and 19,967 non-redundant structural variants (SVs; ≥30 bp) across 687 S. cerevisiae isolates. Comparing these variants with synonymous SNPs (sSNPs) as neutral controls, we found that the majority of the derived nonsynonymous SNPs (nSNPs), indels, and SVs were deleterious. Heterozygosity was positively correlated with the impact of deleterious SNPs, suggesting a role of genetic diversity in mitigating their effects. The domesticated isolates exhibited a higher additive burden of deleterious SNPs (dSNPs) than the wild isolates, but a lower burden of indels and SVs. Moreover, the domesticated S. cerevisiae showed reduced rates of adaptive evolution relative to the wild S. cerevisiae. In summary, deleterious variants tend to be heterozygous, which may mitigate their harmful effects, but they also constrain breeding potential. Addressing deleterious alleles and minimizing the genetic load are crucial considerations for future S. cerevisiae breeding efforts.

Plant pangenomes for crop improvement, biodiversity and evolution

Plant genome sequences catalogue genes and the genetic elements that regulate their expression. Such inventories further research aims as diverse as mapping the molecular basis of trait diversity in domesticated plants or inquiries into the origin of evolutionary innovations in flowering plants millions of years ago. The transformative technological progress of DNA sequencing in the past two decades has enabled researchers to sequence ever more genomes with greater ease. Pangenomes - complete sequences of multiple individuals of a species or higher taxonomic unit - have now entered the geneticists' toolkit. The genomes of crop plants and their wild relatives are being studied with translational applications in breeding in mind. But pangenomes are applicable also in ecological and evolutionary studies, as they help classify and monitor biodiversity across the tree of life, deepen our understanding of how plant species diverged and show how plants adapt to changing environments or new selection pressures exerted by human beings.

Identification, Elucidation and Deployment of a Cytoplasmic Male Sterility System for Hybrid Potato

Recent advances in diploid F1 hybrid potato breeding rely on the production of inbred lines using the S-locus inhibitor (Sli) gene. As a result of this method, female parent lines are self-fertile and require emasculation before hybrid seed production. The resulting F1 hybrids are self-fertile as well and produce many undesirable berries in the field. Utilization of cytoplasmic male sterility would eliminate the need for emasculation, resulting in more efficient hybrid seed production and male sterile F1 hybrids. We observed plants that completely lacked anthers in an F2 population derived from an interspecific cross between diploid S. tuberosum and S. microdontum. We studied the antherless trait to determine its suitability for use in hybrid potato breeding. We mapped the causal locus to the short arm of Chromosome 6, developed KASP markers for the antherless (al) locus and introduced it into lines with T and A cytoplasm. We found that antherless type male sterility is not expressed in T and A cytoplasm, proving that it is a form of CMS. We hybridized male sterile al/al plants with P cytoplasm with pollen from al/al plants with T and A cytoplasm and we show that the resulting hybrids set significantly fewer berries in the field. Here, we show that the antherless CMS system can be readily deployed in diploid F1 hybrid potato breeding to improve hybridization efficiency and reduce berry set in the field.

Harnessing clonal gametes in hybrid crops to engineer polyploid genomes

Heterosis boosts crop yield; however, harnessing additional progressive heterosis in polyploids is challenging for breeders. We bioengineered a 'mitosis instead of meiosis' (MiMe) system that generates unreduced, clonal gametes in three hybrid tomato genotypes and used it to establish polyploid genome design. Through the hybridization of MiMe hybrids, we generated '4-haplotype' plants that encompassed the complete genetics of their four inbred grandparents, providing a blueprint for exploiting polyploidy in crops.

Population comparative genomics discovers gene gain and loss during grapevine domestication

Plant domestication are evolutionary experiments conducted by early farmers since thousands years ago, during which the crop wild progenitors are artificially selected for desired agronomic traits along with dramatic genomic variation in the course of moderate to severe bottlenecks. However, previous investigations are mainly focused on small-effect variants, while changes in gene contents are rarely investigated due to the lack of population-level assemblies for both the crop and its wild relatives. Here, we applied comparative genomic analyses to discover gene gain and loss during grapevine domestication using long-read assemblies of representative population samples for both domesticated grapevines (V. vinifera ssp. vinifera) and their wild progenitors (V. vinifera ssp. sylvestris). Only ∼7% of gene families were shared by 16 Vitis genomes while ∼8% of gene families were specific to each accession, suggesting dramatic variations of gene contents in grapevine genomes. Compared to wild progenitors, the domesticated accessions exhibited an increased presence of genes associated with asexual reproduction, while the wild progenitors showcased a higher abundance of genes related to pollination, revealing the transition from sexual reproduction to clonal propagation during domestication processes. Moreover, the domesticated accessions harbored fewer disease-resistance genes than wild progenitors. The SVs occurred frequently in aroma and disease-resistance related genes between domesticated grapevines and wild progenitors, indicating the rapid diversification of these genes during domestication. Our study provides insights and resources for biological studies and breeding programs in grapevine.

Development of near homozygous lines for diploid hybrid TPS breeding in potatoes

Diploid inbred-based F1 hybrid True Potato Seed (DHTPS) breeding is a novel technique to transform potato breeding and cultivation across the globe. Significant efforts are being made to identify elite diploids, dihaploids and develop diploid inbred lines for heterosis exploitation in potatoes. Self-incompatibility is the first obstacle for developing inbred lines in diploid potatoes, which necessitates the introgression of a dominant S locus inhibitor gene (Sli) for switching self-incompatibility to self-compatibility. We evaluated a set of 357 diploid clones in different selfing generations for self-compatibility and degree of homozygosity using Kompetitive Allele Specific PCR (KASP) Single Nucleotide Polymorphism (SNP) markers. A subset of 10 KASP markers of the Sli candidate region on chromosome 12 showed an association with the phenotype for self-compatibility. The results revealed that the selected 10 KASP markers for the Sli gene genotype could be deployed for high throughput rapid screening of self-compatibility in diploid populations and to identify new sources of self-compatibility. The homozygosity assessed through 99 KASP markers distributed across all the chromosomes of the potato genome was 20-78 % in founder diploid clones, while different selfing generations, i.e., S0, S1, S2 and S3 observed 36.1-80.4, 56.9-82.8, 59.5-85.4 and 73.7-87.8 % average homozygosity, respectively. The diploid plants with ∼80 % homozygosity were also observed in the first selfing generation, which inferred that homozygosity assessment in the early generations itself could identify the best plants with high homozygosity to speed up the generation of diploid inbred lines.

A survey of the Sli gene in wild and cultivated potato

Inbred-hybrid breeding of diploid potatoes necessitates breeding lines that are self-compatible. One way of incorporating self-compatibility into incompatible cultivated potato (Solanum tuberosum) germplasm is to introduce the S-locus inhibitor gene (Sli), which functions as a dominant inhibitor of gametophytic self-incompatibility. To learn more about Sli diversity and function in wild species relatives of cultivated potato, we obtained Sli gene sequences that extended from the 5'UTR to the 3'UTR from 133 individuals from 22 wild species relatives of potato and eight diverse cultivated potato clones. DNA sequence alignment and phylogenetic trees based on genomic and protein sequences show that there are two highly conserved groups of Sli sequences. DNA sequences in one group contain the 533 bp insertion upstream of the start codon identified previously in self-compatible potato. The second group lacks the insertion. Three diploid and four polyploid individuals of wild species collected from geographically disjointed localities contained Sli with the 533 bp insertion. For most of the wild species clones examined, however, Sli did not have the insertion. Phylogenetic analysis indicated that Sli sequences with the insertion, in wild species and in cultivated clones, trace back to a single origin. Some diploid wild potatoes that have Sli with the insertion were self-incompatible and some wild potatoes that lack the insertion were self-compatible. Although there is evidence of positive selection for some codon positions in Sli, there is no evidence of diversifying selection at the gene level. In silico analysis of Sli protein structure did not support the hypothesis that amino acid changes from wild-type (no insertion) to insertion-type account for changes in protein function. Our study demonstrated that genetic factors besides the Sli gene must be important for conditioning a switch in the mating system from self-incompatible to self-compatible in wild potatoes.

Characterization of FBA genes in potato (Solanum tuberosum L.) and expression patterns in response to light spectrum and abiotic stress

Fructose-1, 6-bisphosphate aldolase (FBA) plays vital roles in plant growth, development, and response to abiotic stress. However, genome-wide identification and structural characterization of the potato (Solanum tuberosum L.) FBA gene family has not been systematically analyzed. In this study, we identified nine StFBA gene members in potato, with six StFBA genes localized in the chloroplast and three in the cytoplasm. The analysis of gene structures, protein structures, and phylogenetic relationships indicated that StFBA genes were divided into Class I and II, which exhibited significant differences in structure and function. Synteny analysis revealed that segmental duplication events promoted the expansion of the StFBA gene family. Promoter analysis showed that most StFBA genes contained cis-regulatory elements associated with light and stress responses. Expression analysis showed that StFBA3, StFBA8, and StFBA9 showing significantly higher expression levels in leaf, stolon, and tuber under blue light, indicating that these genes may improve photosynthesis and play an important function in regulating the induction and expansion of microtubers. Expression levels of the StFBA genes were influenced by drought and salt stress, indicating that they played important roles in abiotic stress. This work offers a theoretical foundation for in-depth understanding of the evolution and function of StFBA genes, as well as providing the basis for the genetic improvement of potatoes.

Identification of two mutant JASON-RELATED genes associated with unreduced pollen production in potato

KEY MESSAGE

Multiple QTLs control unreduced pollen production in potato. Two major-effect QTLs co-locate with mutant alleles of genes with homology to AtJAS, a known regulator of meiotic spindle orientation. In diploid potato the production of unreduced gametes with a diploid (2n) rather than a haploid (n) number of chromosomes has been widely reported. Besides their evolutionary important role in sexual polyploidisation, unreduced gametes also have a practical value for potato breeding as a bridge between diploid and tetraploid germplasm. Although early articles argued for a monogenic recessive inheritance, the genetic basis of unreduced pollen production in potato has remained elusive. Here, three diploid full-sib populations were genotyped with an amplicon sequencing approach and phenotyped for unreduced pollen production across two growing seasons. We identified two minor-effect and three major-effect QTLs regulating this trait. The two QTLs with the largest effect displayed a recessive inheritance and an additive interaction. Both QTLs co-localised with genes encoding for putative AtJAS homologs, a key regulator of meiosis II spindle orientation in Arabidopsis thaliana. The function of these candidate genes is consistent with the cytological phenotype of mis-oriented metaphase II plates observed in the parental clones. The alleles associated with elevated levels of unreduced pollen showed deleterious mutation events: an exonic transposon insert causing a premature stop, and an amino acid change within a highly conserved domain. Taken together, our findings shed light on the natural variation underlying unreduced pollen production in potato and will facilitate interploidy breeding by enabling marker-assisted selection for this trait.

Identification and Characterization of the BZR Transcription Factor Genes Family in Potato (Solanum tuberosum L.) and Their Expression Profiles in Response to Abiotic Stresses

Brassinazole resistant (BZR) genes act downstream of the brassinosteroid signaling pathway regulating plant growth and development and participating in plant stress responses. However, the BZR gene family has not systematically been characterized in potato. We identified eight BZR genes in Solanum tuberosum, which were distributed among seven chromosomes unequally and were classified into three subgroups. Potato and tomato BZR proteins were shown to be closely related with high levels of similarity. The BZR gene family members in each subgroup contained similar conserved motifs. StBZR genes exhibited tissue-specific expression patterns, suggesting their functional differentiation during evolution. StBZR4, StBZR7, and StBZR8 were highly expressed under white light in microtubers. StBZR1 showed a progressive up-regulation from 0 to 6 h and a progressive down-regulation from 6 to 24 h after drought and salt stress. StBZR1, StBZR2, StBZR4, StBZR5, StBZR6, StBZR7 and StBZR8 were significantly induced from 0 to 3 h under BR treatment. This implied StBZR genes are involved in phytohormone and stress response signaling pathways. Our results provide a theoretical basis for understanding the functional mechanisms of BZR genes in potato.

Crossover shortage in potato is caused by StMSH4 mutant alleles and leads to either highly uniform unreduced pollen or sterility

The balanced segregation of homologous chromosomes during meiosis is essential for fertility and is mediated by crossovers (COs). A strong reduction of CO number leads to the unpairing of homologous chromosomes after the withdrawal of the synaptonemal complex. This results in the random segregation of univalents during meiosis I and ultimately to the production of unbalanced and sterile gametes. However, if CO shortage is combined with another meiotic alteration that restitutes the first meiotic division, then uniform and balanced unreduced male gametes, essentially composed of nonrecombinant homologs, are produced. This mitosis-like division is of interest to breeders because it transmits most of the parental heterozygosity to the gametes. In potato, CO shortage, a recessive trait previously referred to as desynapsis, was tentatively mapped to chromosome 8. In this article, we have fine-mapped the position of the CO shortage locus and identified StMSH4, an essential component of the class I CO pathway, as the most likely candidate gene. A 7 base-pair insertion in the second exon of StMSH4 was found to be associated with CO shortage in our mapping population. We also identified a second allele with a 3,820 base-pair insertion and confirmed that both alleles cannot complement each other. Such nonfunctional alleles appear to be common in potato cultivars. More than half of the varieties we tested are carriers of mutational load at the StMSH4 locus. With this new information, breeders can choose to remove alleles associated with CO shortage from their germplasm to improve fertility or to use them to produce highly uniform unreduced male gametes in alternative breeding schemes.

Potato and sweetpotato breeding at the international potato center: approaches, outcomes and the way forward

Root and tuber crop breeding is at the front and center of CIP's science program, which seeks to develop and disseminate sustainable agri-food technologies, information and practices to serve objectives including poverty alleviation, income generation, food security and the sustainable use of natural resources. CIP was established in 1971 in Peru, which is part of potato's center of origin and diversity, with an initial mandate on potato and expanding to include sweetpotato in 1986. Potato and sweetpotato are among the top 10 most consumed food staples globally and provide some of the most affordable sources of energy and vital nutrients. Sweetpotato plays a key role in securing food for many households in Africa and South Asia, while potato is important worldwide. Both crops grow in a range of conditions with relatively few inputs and simple agronomic techniques. Potato is adapted to the cooler environments, while sweetpotato grows well in hot climates, and hence, the two crops complement each other. Germplasm enhancement (pre-breeding), the development of new varieties and building capacity for breeding and variety testing in changing climates with emphasis on adaptation, resistance, nutritional quality and resource-use efficiency are CIP's central activities with significant benefits to the poor. Investments in potato and sweetpotato breeding and allied disciplines at CIP have resulted in the release of many varieties some of which have had documented impact in the release countries. Partnership with diverse types of organizations has been key to the centers way of working toward improving livelihoods through crop production in the global South.

Challenges for crop improvement

The genetic improvement of crops faces the significant challenge of feeding an ever-increasing population amidst a changing climate, and when governments are adopting a 'more with less' approach to reduce input use. Plant breeding has the potential to contribute to the United Nations Agenda 2030 by addressing various sustainable development goals (SDGs), with its most profound impact expected on SDG2 Zero Hunger. To expedite the time-consuming crossbreeding process, a genomic-led approach for predicting breeding values, targeted mutagenesis through gene editing, high-throughput phenomics for trait evaluation, enviromics for including characterization of the testing environments, machine learning for effective management of large datasets, and speed breeding techniques promoting early flowering and seed production are being incorporated into the plant breeding toolbox. These advancements are poised to enhance genetic gains through selection in the cultigen pools of various crops. Consequently, these knowledge-based breeding methods are pursued for trait introgression, population improvement, and cultivar development. This article uses the potato crop as an example to showcase the progress being made in both genomic-led approaches and gene editing for accelerating the delivery of genetic gains through the utilization of genetically enhanced elite germplasm. It also further underscores that access to technological advances in plant breeding may be influenced by regulations and intellectual property rights.

Genetic interrogation of phenotypic plasticity informs genome-enabled breeding in cotton

Phenotypic plasticity, or the ability to adapt to and thrive in changing climates and variable environments, is essential for developmental programs in plants. Despite its importance, the genetic underpinnings of phenotypic plasticity for key agronomic traits remain poorly understood in many crops. In this study, we aim to fill this gap by using genome-wide association studies to identify genetic variations associated with phenotypic plasticity in upland cotton (Gossypium hirsutum L.). We identified 73 additive quantitative trait loci (QTLs), 32 dominant QTLs, and 6799 epistatic QTLs associated with 20 traits. We also identified 117 additive QTLs, 28 dominant QTLs, and 4691 epistatic QTLs associated with phenotypic plasticity in 19 traits. Our findings reveal new genetic factors, including additive, dominant, and epistatic QTLs, that are linked to phenotypic plasticity and agronomic traits. Meanwhile, we find that the genetic factors controlling the mean phenotype and phenotypic plasticity are largely independent in upland cotton, indicating the potential for simultaneous improvement. Additionally, we envision a genomic design strategy by utilizing the identified QTLs to facilitate cotton breeding. Taken together, our study provides new insights into the genetic basis of phenotypic plasticity in cotton, which should be valuable for future breeding.

Crop adaptation to climate change: An evolutionary perspective

The disciplines of evolutionary biology and plant and animal breeding have been intertwined throughout their development, with responses to artificial selection yielding insights into the action of natural selection and evolutionary biology providing statistical and conceptual guidance for modern breeding. Here we offer an evolutionary perspective on a grand challenge of the 21st century: feeding humanity in the face of climate change. We first highlight promising strategies currently under way to adapt crops to current and future climate change. These include methods to match crop varieties with current and predicted environments and to optimize breeding goals, management practices, and crop microbiomes to enhance yield and sustainable production. We also describe the promise of crop wild relatives and recent technological innovations such as speed breeding, genomic selection, and genome editing for improving environmental resilience of existing crop varieties or for developing new crops. Next, we discuss how methods and theory from evolutionary biology can enhance these existing strategies and suggest novel approaches. We focus initially on methods for reconstructing the evolutionary history of crops and their pests and symbionts, because such historical information provides an overall framework for crop-improvement efforts. We then describe how evolutionary approaches can be used to detect and mitigate the accumulation of deleterious mutations in crop genomes, identify alleles and mutations that underlie adaptation (and maladaptation) to agricultural environments, mitigate evolutionary trade-offs, and improve critical proteins. Continuing feedback between the evolution and crop biology communities will ensure optimal design of strategies for adapting crops to climate change.

Unlikely heroes on the long and winding road to potato inbreeding

Conversion of potato from a tetraploid, heterozygous, vegetatively propagated crop to a diploid F1 hybrid, propagated via botanical seed, would constitute a considerable advance for global agriculture, but faces multiple challenges. One such challenge is the difficulty in inbreeding potato, which involves purging deleterious alleles from its genome. This commentary discusses possible reasons for this difficulty and highlights a recent sequence-based effort to classify SNP variation, in potato germplasm, according to its deleterious potential. Tools and strategies connected to this database may facilitate development of F1 hybrids.

Solanum americanum genome-assisted discovery of immune receptors that detect potato late blight pathogen effectors

Potato (Solanum tuberosum) and tomato (Solanum lycopersicon) crops suffer severe losses to late blight caused by the oomycete pathogen Phytophthora infestans. Solanum americanum, a relative of potato and tomato, is globally distributed and most accessions are highly blight resistant. We generated high-quality reference genomes of four S. americanum accessions, resequenced 52 accessions, and defined a pan-NLRome of S. americanum immune receptor genes. We further screened for variation in recognition of 315P. infestans RXLR effectors in 52 S. americanum accessions. Using these genomic and phenotypic data, we cloned three NLR-encoding genes, Rpi-amr4, R02860 and R04373, that recognize cognate P. infestans RXLR effectors PITG_22825 (AVRamr4), PITG_02860 and PITG_04373. These genomic resources and methodologies will support efforts to engineer potatoes with durable late blight resistance and can be applied to diseases of other crops.

Dissected Leaf 1 encodes an MYB transcription factor that controls leaf morphology in potato

KEY MESSAGE

The transcription factor StDL1 regulates dissected leaf formation in potato and the genotype frequency of recessive Stdl1/Stdl1, which results in non-dissected leaves, has increased in cultivated potatoes. Leaf morphology is a key trait of plants, influencing plant architecture, photosynthetic efficiency and yield. Potato (Solanum tuberosum L.), the third most important food crop worldwide, has a diverse leaf morphology. However, despite the recent identification of several genes regulating leaf formation in other plants, few genes involved in potato leaf development have been reported. In this study, we identified an R2R3 MYB transcription factor, Dissected Leaf 1 (StDL1), regulating dissected leaf formation in potato. A naturally occurring allele of this gene, Stdl1, confers non-dissected leaves in young seedlings. Knockout of StDL1 in a diploid potato changes the leaf morphology from dissected to non-dissected. Experiments in N. benthamiana and yeast show that StDL1 is a transcriptional activator. Notably, by calculating the genotype frequency of the Stdl1/Stdl1 in 373-potato accessions, we found that it increases significantly in cultivated potatoes. This work reveals the genetic basis of dissected leaf formation in potato and provides insights into plant leaf morphology.

Unraveling Prevalence and Effects of Deleterious Mutations in Maize Elite Lines across Decades of Modern Breeding

Future breeding is likely to involve the detection and removal of deleterious alleles, which are mutations that negatively affect crop fitness. However, little is known about the prevalence of such mutations and their effects on phenotypic traits in the context of modern crop breeding. To address this, we examined the number and frequency of deleterious mutations in 350 elite maize inbred lines developed over the past few decades in China and the United States. Our findings reveal an accumulation of weakly deleterious mutations and a decrease in strongly deleterious mutations, indicating the dominant effects of genetic drift and purifying selection for the two types of mutations, respectively. We also discovered that slightly deleterious mutations, when at lower frequencies, were more likely to be heterozygous in the developed hybrids. This is consistent with complementation as a potential explanation for heterosis. Subsequently, we found that deleterious mutations accounted for more of the variation in phenotypic traits than nondeleterious mutations with matched minor allele frequencies, especially for traits related to leaf angle and flowering time. Moreover, we detected fewer deleterious mutations in the promoter and gene body regions of differentially expressed genes across breeding eras than in nondifferentially expressed genes. Overall, our results provide a comprehensive assessment of the prevalence and impact of deleterious mutations in modern maize breeding and establish a useful baseline for future maize improvement efforts.