Genetic Analysis of Methyl Anthranilate, Mesifurane, Linalool, and Other Flavor Compounds in Cultivated Strawberry (Fragaria × ananassa)

Improvement of crop production in controlled environment agriculture through breeding

Controlled environment agriculture (CEA) represents one of the fastest-growing sectors of horticulture. Production in controlled environments ranges from highly controlled indoor environments with 100% artificial lighting (vertical farms or plant factories) to high-tech greenhouses with or without supplemental lighting, to simpler greenhouses and high tunnels. Although food production occurs in the soil inside high tunnels, most CEA operations use various hydroponic systems to meet crop irrigation and fertility needs. The expansion of CEA offers promise as a tool for increasing food production in and near urban systems as these systems do not rely on arable agricultural land. In addition, CEA offers resilience to climate instability by growing inside protective structures. Products harvested from CEA systems tend to be of high quality, both internal and external, and are sought after by consumers. Currently, CEA producers rely on cultivars bred for production in open-field agriculture. Because of high energy and other production costs in CEA, only a limited number of food crops have proven themselves to be profitable to produce. One factor contributing to this situation may be a lack of optimized cultivars. Indoor growing operations offer opportunities for breeding cultivars that are ideal for these systems. To facilitate breeding these specialized cultivars, a wide range of tools are available for plant breeders to help speed this process and increase its efficiency. This review aims to cover breeding opportunities and needs for a wide range of horticultural crops either already being produced in CEA systems or with potential for CEA production. It also reviews many of the tools available to breeders including genomics-informed breeding, marker-assisted selection, precision breeding, high-throughput phenotyping, and potential sources of germplasm suitable for CEA breeding. The availability of published genomes and trait-linked molecular markers should enable rapid progress in the breeding of CEA-specific food crops that will help drive the growth of this industry.

A telomere-to-telomere phased genome of an octoploid strawberry reveals a receptor kinase conferring anthracnose resistance

BACKGROUND

Cultivated strawberry (Fragaria xananassa Duch.), an allo-octoploid species arising from at least 3 diploid progenitors, poses a challenge for genomic analysis due to its high levels of heterozygosity and the complex nature of its polyploid genome.

RESULTS

This study developed the complete haplotype-phased genome sequence from a short-day strawberry, 'Florida Brilliance' without parental data, assembling 56 chromosomes from telomere to telomere. This assembly was achieved with high-fidelity long reads and high-throughput chromatic capture sequencing (Hi-C). The centromere core regions and 96,104 genes were annotated using long-read isoform RNA sequencing. Using the high quality of the haplotype-phased reference genome, FaFB1, we identified the causal mutation within the gene encoding Leaf Rust 10 Disease-Resistance Locus Receptor-like Protein Kinase (LRK10) that confers resistance to anthracnose fruit rot (AFR). This disease is caused by the Colletotrichum acutatum species complex and results in significant economic losses in strawberry production. Comparison of resistant and susceptible haplotype assemblies and full-length transcript data revealed a 29-bp insertion at the first exon of the susceptible allele, leading to a premature stop codon and loss of gene function. The functional role of LRK10 in resistance to AFR was validated using a simplified Agrobacterium-based transformation method for transient gene expression analysis in strawberry fruits. Transient knockdown and overexpression of LRK10 in fruit indicate a key role for LRK10 in AFR resistance in strawberry.

CONCLUSIONS

The FaFB1 assembly along with other resources will be valuable for the discovery of additional candidate genes associated with disease resistance and fruit quality, which will not only advance our understanding of genes and their functions but also facilitate advancements in genome editing in strawberry.

Genome-wide association studies in a diverse strawberry collection unveil loci controlling agronomic and fruit quality traits

Strawberries (Fragaria sp.) are cherished for their organoleptic properties and nutritional value. However, breeding new cultivars involves the simultaneous selection of many agronomic and fruit quality traits, including fruit firmness and extended postharvest life. The strawberry germplasm collection here studied exhibited extensive phenotypic variation in 26 agronomic and fruit quality traits across three consecutive seasons. Phenotypic correlations and principal component analysis revealed relationships among traits and accessions, emphasizing the impact of plant breeding on fruit weight and firmness to the detriment of sugar or vitamin C content. Genetic diversity analysis on 124 accessions using 44,408 markers denoted a population structure divided into six subpopulations still retaining considerable diversity. Genome-wide association studies for the 26 traits unveiled 121 significant marker-trait associations distributed across 95 quantitative trait loci (QTLs). Multiple associations were detected for fruit firmness, a key breeding target, including a prominent locus on chromosome 6A. The candidate gene FaPG1, controlling fruit softening and postharvest shelf life, was identified within this QTL region. Differential expression of FaPG1 confirmed its role as the primary contributor to natural variation in fruit firmness. A kompetitive allele-specific PCR assay based on the single nucleotide polymorphism (SNP) AX-184242253, associated with the 6A QTL, predicts a substantial increase in fruit firmness, validating its utility for marker-assisted selection. In essence, this comprehensive study provides insights into the phenotypic and genetic landscape of the strawberry collection and lays a robust foundation for propelling the development of superior strawberry cultivars through precision breeding.

Volatile flavor behavior characterization of Hericium erinaceus during postharvest storage using E-nose, HS-GC-IMS, and HS-SPME-GC-MS after treated with electron-beam generated X-ray irradiation

Flavor alteration is a crucial factor affecting the quality of mushrooms during preservation. The dynamic variations of volatile profiles of fresh Hericium erinaceus with electron-beam generated X-ray irradiation were investigated by combining E-nose, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). E-nose analysis achieved rapid discrimination in all treatments over storage time. 65 and 73 volatile organic compounds (VOCs) were identified by HS-GC-IMS and HS-SPME-GC-MS, respectively. Thereinto, 1-octen-3-ol, 1-octen-3-one, and 2-octanone were screened out as the characteristic VOCs, which contents declined during storage. While the contents of (E)-2-octenal, (E)-2-nonenal, and 1-octanol increased. The flavor profile changes from distinct mushroom and floral odor to an intense alcohol and fatty odor. Notably, one-kGy irradiation remained more volatiles and denser mushroom odor after storage. Multivariate analysis further confirmed that 1.0 kGy irradiation contributed to the overall aroma retention during postharvest storage of H. erinaceus.

Advances in genomics and genome editing for improving strawberry (Fragaria ×ananassa)

The cultivated strawberry, Fragaria ×ananassa, is a recently domesticated fruit species of economic interest worldwide. As such, there is significant interest in continuous varietal improvement. Genomics-assisted improvement, including the use of DNA markers and genomic selection have facilitated significant improvements of numerous key traits during strawberry breeding. CRISPR/Cas-mediated genome editing allows targeted mutations and precision nucleotide substitutions in the target genome, revolutionizing functional genomics and crop improvement. Genome editing is beginning to gain traction in the more challenging polyploid crops, including allo-octoploid strawberry. The release of high-quality reference genomes and comprehensive subgenome-specific genotyping and gene expression profiling data in octoploid strawberry will lead to a surge in trait discovery and modification by using CRISPR/Cas. Genome editing has already been successfully applied for modification of several strawberry genes, including anthocyanin content, fruit firmness and tolerance to post-harvest disease. However, reports on many other important breeding characteristics associated with fruit quality and production are still lacking, indicating a need for streamlined genome editing approaches and tools in Fragaria ×ananassa. In this review, we present an overview of the latest advancements in knowledge and breeding efforts involving CRISPR/Cas genome editing for the enhancement of strawberry varieties. Furthermore, we explore potential applications of this technology for improving other Rosaceous plant species.

Analysis of volatile organic compounds in Korean-bred strawberries: insights for improving fruit flavor

Introduction

The strawberry industry in South Korea has witnessed a significant 65% growth over the past decade, surpassing other fruits and vegetables in production value. While sweetness and acidity are well-recognized flavor determinants, the role of volatile organic compounds (VOCs) in defining the desirable flavor profiles of strawberries is also crucial. However, existing research has predominantly concentrated on a limited range of commercial cultivars, neglecting the broader spectrum of strawberry varieties.

Methods

This study embarked on developing a comprehensive VOC database for a diverse array of strawberry cultivars sourced both domestically and internationally. A total of 61 different strawberry cultivars from Korea (45), the USA (7), Japan (8), and France (1) were analyzed for their VOC content using Tenax TA Thermo Desorption tubes and Gas Chromatography-Mass Spectrometry (GC-MS). In addition to VOC profiling, heritability was assessed using one-way ANOVA to compare means among multiple groups, providing insights into the genetic basis of flavor differences.

Results and discussion

The analysis identified 122 compounds categorized into esters, alcohols, terpenes, and lactones, with esters constituting the majority (46.5%) of total VOCs in Korean cultivars. 'Arihyang', 'Sunnyberry', and 'Kingsberry' exhibited the highest diversity of VOCs detected (97 types), whereas 'Seolhong' showed the highest overall concentration (57.5mg·kg-1 FW). Compared to the USA cultivars, which were abundant in γ-decalactone (a peach-like fruity aroma), most domestic cultivars lacked this compound. Notably, 'Misohyang' displayed a high γ-decalactone content, highlighting its potential as breeding germplasm to improve flavor in Korean strawberries. The findings underscore the importance of a comprehensive VOC analysis across different strawberry cultivars to understand flavor composition. The significant variation in VOC content among the cultivars examined opens avenues for targeted breeding strategies. By leveraging the distinct VOC profiles, particularly the presence of γ-decalactone, breeders can develop new strawberry varieties with enhanced flavor profiles, catering to consumer preferences for both domestic and international markets.

Mechanisms of methyl 2-methylbutyrate suppression on Aspergillus flavus growth and aflatoxin B1 biosynthesis

Aspergillus flavus and subsequently produced carcinogenic aflatoxins frequently contaminate postharvest food crops, resulting in a threat to global food safety. Chemical preservatives are currently the main antifungal agents. However, fungal resistance effect, biological toxicity, and environmental contamination limit their practical applications. The application of natural volatile organic compounds has great potential for controlling fungal and mycotoxin contamination of postharvest food crops. This study therefore investigated the antifungal and anti-aflatoxigenic activities of the volatile compound, methyl 2-methylbutyrate (M2M), against Aspergillus flavus and its potential mechanisms. M2M effectively inhibited A. flavus mycelia growth, with a minimum inhibitory concentration of 2.0 μL/mL. Moreover, M2M also suppressed aflatoxin production, sclerotia production, and the pathogenicity on peanut and corn flour. RNA-Seq results showed that 2899 differentially expressed genes (DEGs), and DEGs involved in ergosterol synthesis, cell wall structure, glycolysis, citric acid cycle, mitogen activated protein kinase signaling pathway, DNA replication, and aflatoxin biosynthesis, were down-regulated in A. flavus. Further studies showed that M2M strongly damaged the cell membrane and cell wall integrity, reduced ATP levels, and induced reactive oxygen species (ROS) accumulation and DNA damage. Notably, a GATA type zinc finger transcription factor, AfSreA (AFLA_132440), which is essential for A. flavus growth and aflatoxin production, was identified. The growth and aflatoxin yield in the ΔAfSreA strain decreased by 94.94 % and 71.82 %, respectively. Additionally, deletion of AfSreA destroyed cell wall integrity and decreased expressions of genes involved in aflatoxin biosynthesis. Taken together, our results identified the antifungal and anti-aflatoxigenic mechanisms of M2M against A. flavus, and confirmed the potential of M2M in protecting peanut and corn from fungal contamination.

Identification of ethyl vanillin in strawberry (Fragaria × ananassa) using a targeted metabolomics strategy: From artificial to natural

Improving flavor can be an important goal of strawberry through breeding that is enhanced through the accurate identification and quantification of flavor compounds. Herein, a targeted metabolomics strategy was developed using liquid-liquid extraction, an in-house standard database, and GC-MS/MS analysis. The database consisted of key food odorants (KFOs), artificial flavor compounds (AFCs) and volatiles. A total of 131 flavor compounds were accurately identified in Medallion® 'FL 16.30-128' strawberry. Importantly, ethyl vanillin was identified for the first time in natural food. Multiple techniques, including GC-MS, GC-MS/MS and UPLC-MS/MS were applied to ensure the identification. The ethyl vanillin in the Medallion® samples were determined in a range of concentrations from 0.070 ± 0.0006 µg/kg to 0.1372 ± 0.0014 µg/kg by using stable isotope dilution analysis. The identification of ethyl vanillin in strawberry implys the future commercial use a natural flavor compound and the potential to identify genes and proteins associated with its biosynthesis.

A medium-density genotyping platform for cultivated strawberry using DArTag technology

Genomic prediction in breeding populations containing hundreds to thousands of parents and seedlings is prohibitively expensive with current high-density genetic marker platforms designed for strawberry. We developed mid-density panels of molecular inversion probes (MIPs) to be deployed with the "DArTag" marker platform to provide a low-cost, high-throughput genotyping solution for strawberry genomic prediction. In total, 7742 target single nucleotide polymorphism (SNP) regions were used to generate MIP assays that were tested with a screening panel of 376 octoploid Fragaria accessions. We evaluated the performance of DArTag assays based on genotype segregation, amplicon coverage, and their ability to produce subgenome-specific amplicon alignments to the FaRR1 assembly and subsequent alignment-based variant calls with strong concordance to DArT's alignment-free, count-based genotype reports. We used a combination of marker performance metrics and physical distribution in the FaRR1 assembly to select 3K and 5K production panels for genotyping of large strawberry populations. We show that the 3K and 5K DArTag panels are able to target and amplify homologous alleles within subgenomic sequences with low-amplification bias between reference and alternate alleles, supporting accurate genotype calling while producing marker genotypes that can be treated as functionally diploid for quantitative genetic analysis. The 3K and 5K target SNPs show high levels of polymorphism in diverse F. × ananassa germplasm and UC Davis cultivars, with mean pairwise diversity (π) estimates of 0.40 and 0.32 and mean heterozygous genotype frequencies of 0.35 and 0.33, respectively.

Diversity of the volatilome and the fruit size and shape in European woodland strawberry (Fragaria vesca)

Woodland strawberry (Fragaria vesca subsp. vesca) is a wild relative of cultivated strawberry (F. × ananassa) producing small and typically conical fruits with an intense flavor and aroma. The wild strawberry species, F. vesca, is a rich resource of genetic and metabolic variability, but its diversity remains largely unexplored and unexploited. In this study, we aim for an in-depth characterization of the fruit complex volatilome by GC-MS as well as the fruit size and shape using a European germplasm collection that represents the continental diversity of the species. We report characteristic volatilome footprints and fruit phenotypes of specific geographical areas. Thus, this study uncovers phenotypic variation linked to geographical distribution that will be valuable for further genetic studies to identify candidate genes or develop markers linked to volatile compounds or fruit shape and size traits.

Molecular bases of strawberry fruit quality traits: Advances, challenges, and opportunities

The strawberry is one of the world's most popular fruits, providing humans with vitamins, fibers, and antioxidants. Cultivated strawberry (Fragaria × ananassa) is an allo-octoploid and highly heterozygous, making it a challenge for breeding, quantitative trait locus (QTL) mapping, and gene discovery. Some wild strawberry relatives, such as Fragaria vesca, have diploid genomes and are becoming laboratory models for the cultivated strawberry. Recent advances in genome sequencing and CRISPR-mediated genome editing have greatly improved the understanding of various aspects of strawberry growth and development in both cultivated and wild strawberries. This review focuses on fruit quality traits that are most relevant to the consumers, including fruit aroma, sweetness, color, firmness, and shape. Recently available phased-haplotype genomes, single nucleotide polymorphism (SNP) arrays, extensive fruit transcriptomes, and other big data have made it possible to locate key genomic regions or pinpoint specific genes that underlie volatile synthesis, anthocyanin accumulation for fruit color, and sweetness intensity or perception. These new advances will greatly facilitate marker-assisted breeding, the introgression of missing genes into modern varieties, and precise genome editing of selected genes and pathways. Strawberries are poised to benefit from these recent advances, providing consumers with fruit that is tastier, longer-lasting, healthier, and more beautiful.

Variation in Volatile Organic Compounds in native, synanthropic accessions and cultivars of the musk strawberry (Fragaria moschata Duchesne ex Weston)

Prior to the world-wide dominance of F. ×ananassa in strawberry production, native species had been cultivated in European gardens for centuries. Especially the musk strawberry (F. moschata) had been highly appreciated due to its fruit size and extraordinary aroma. Detailed studies on the diversity of the species' fruit aroma are lacking, although breeding aims to improve strawberry aroma by complex crossings during recent years. Today a few cultivars, abandoned synanthropic occurrences and native populations of this species exist in Germany. Here we characterised aroma profiles of F. moschata accessions by analysing Volatile Organic Compounds. In particular, differences between native and cultivated accessions as well as the diversity in aroma profiles of native populations were investigated. Profiles of Volatile Organic Compounds were analysed by immersion stir bar sorptive extraction-gas chromatography-quadrupol mass spectrometry (imm-SBSE-GC-qMS). These data were compared with a genetic characterisation of samples based on eight microsatellite loci using univariate and multivariate statistical analyses. High amounts of furanones and the key compound methyl anthranilate were characteristic for the aroma profile of F. moschata. We detected a considerable diversity of Volatile Organic Compounds among accessions of F. moschata, particularly among genetically distinct samples from the same population. Native accessions contained more terpenoids but less esters and were moderately differentiated from cultivated samples. The observed patterns of Volatile Organic Compounds indicate that cultivated accessions had been selected for favourable aroma profiles and thus showing traces of domestication. Moreover, native populations harbour a great diversity of Volatile Organic Compounds, which could be also considered for future breeding efforts.

Ectopic Expression of FvVND4c Promotes Secondary Cell Wall Thickening and Flavonoid Accumulation in Fragaria vesca

Secondary cell wall (SCW) thickening has a significant effect on the growth and development of plants, as well as in the resistance to various biotic and abiotic stresses. Lignin accounts for the strength of SCW. It is synthesized through the phenylpropanoid pathway that also leads to flavonoid synthesis. The coupling strategies for lignin and flavonoid syntheses are diverse in plants. How their syntheses are balanced by transcriptional regulation in fleshy fruits is still unclear. The diploid strawberry (Fragaria vesca) is a model for fleshy fruits research due to its small genome and wide scope of genetic transformation. SCW thickening is regulated by a multilevel transcriptional regulatory network wherein vascular-related NAC domains (VNDs) act as key regulators. In this study, we systematically characterized VNDs in Fragaria vesca and explored their functions. The overexpression of FvVND4c in diploid strawberry fruits resulted in SCW thickening and fruit color changes accompanied with the accumulation of lignin and flavonoids. Genes related to these phenotypes were also induced upon FvVND4c overexpression. Among the induced genes, we found FvMYB46 to be a direct downstream regulator of FvVND4c. The overexpression of FvMYB46 resulted in similar phenotypes as FvVND4c, except for the color change. Transcriptomic analyses suggest that both FvVND4c and FvMYB46 act on phenylpropanoid and flavonoid biosynthesis pathways, and induce lignin synthesis for SCW. These results suggest that FvVND4c and FvMYB46 cooperatively regulate SCW thickening and flavonoid accumulation in Fragaria vesca.

Natural variation of respiration-related traits in plants

Plant respiration is one of the greatest global metabolic fluxes, but rates of respiration vary massively both within different cell types as well as between different individuals and different species. Whilst this is well known, few studies have detailed population-level variation of respiration until recently. The last 20 years have seen a renaissance in studies of natural variance. In this review, we describe how experimental breeding populations and collections of large populations of accessions can be used to determine the genetic architecture of plant traits. We further detail how these approaches have been used to study the rate of respiration per se as well as traits that are intimately associated with respiration. The review highlights specific breakthroughs in these areas but also concludes that the approach should be more widely adopted in the study of respiration per se as opposed to the more frequently studied respiration-related traits.

Grapevine genome analysis demonstrates the role of gene copy number variation in the formation of monoterpenes

Volatile organic compounds such as terpenes influence the quality parameters of grapevine through their contribution to the flavour and aroma profile of berries. Biosynthesis of volatile organic compounds in grapevine is relatively complex and controlled by multiple genes, the majority of which are unknown or uncharacterised. To identify the genomic regions that associate with modulation of these compounds in grapevine berries, volatile metabolic data generated via GC-MS from a grapevine mapping population was used to identify quantitative trait loci (QTLs). Several significant QTLs were associated with terpenes, and candidate genes were proposed for sesquiterpene and monoterpene biosynthesis. For monoterpenes, loci on chromosomes 12 and 13 were shown to be associated with geraniol and cyclic monoterpene accumulation, respectively. The locus on chromosome 12 was shown to contain a geraniol synthase gene (VvGer), while the locus on chromosome 13 contained an α-terpineol synthase gene (VvTer). Molecular and genomic investigation of VvGer and VvTer revealed that these genes were found in tandemly duplicated clusters, displaying high levels of hemizygosity. Gene copy number analysis further showed that not only did VvTer and VvGer copy numbers vary within the mapping population, but also across recently sequenced Vitis cultivars. Significantly, VvTer copy number correlated with both VvTer gene expression and cyclic monoterpene accumulation in the mapping population. A hypothesis for a hyper-functional VvTer allele linked to increased gene copy number in the mapping population is presented and can potentially lead to selection of cultivars with modulated terpene profiles. The study highlights the impact of VvTPS gene duplication and copy number variation on terpene accumulation in grapevine.

A multi-omics framework reveals strawberry flavor genes and their regulatory elements

Flavor is essential to consumer preference of foods and is an increasing focus of plant breeding programs. In fruit crops, identifying genes underlying volatile organic compounds has great promise to accelerate flavor improvement, but polyploidy and heterozygosity in many species have slowed progress. Here we use octoploid cultivated strawberry to demonstrate how genomic heterozygosity, transcriptomic intricacy and fruit metabolomic diversity can be treated as strengths and leveraged to uncover fruit flavor genes and their regulatory elements. Multi-omics datasets were generated including an expression quantitative trait loci map with 196 diverse breeding lines, haplotype-phased genomes of a highly-flavored breeding selection, a genome-wide structural variant map using five haplotypes, and volatile genome-wide association study (GWAS) with > 300 individuals. Overlaying regulatory elements, structural variants and GWAS-linked allele-specific expression of numerous genes to variation in volatile compounds important to flavor. In one example, the functional role of anthranilate synthase alpha subunit 1 in methyl anthranilate biosynthesis was supported via fruit transient gene expression assays. These results demonstrate a framework for flavor gene discovery in fruit crops and a pathway to molecular breeding of cultivars with complex and desirable flavor.

Inheritance of esters and other volatile compounds responsible for the fruity aroma in strawberry

Cultivated strawberry, Fragaria  ×  ananassa, has a complex aroma due to the presence of more than 350 volatile organic compounds (VOCs). However, a mixture of only 19 compounds, called Key Volatile Compounds (KVC), can impart the main strawberry aroma. The octoploid nature of the cultivated strawberry species (2n = 8x = 56) adds complexity to the heritance of the accumulation of the volatiles responsible for aroma. An F1 population cross between two breeding parental lines, FC50 and FD54, was phenotyped for aroma by SPME GCMS during six harvests. A total of 58 compounds were identified: 33 esters, nine terpenes, seven aldehydes, four lactones, two furans, one acid, one alkane and one alcohol, of which 16 were KVCs. A total of 179 QTLs were found, and 85 of these were detected in at least three harvests, of which 50 QTLs were considered major (LOD > 4.0) and detected in five or six analyzed harvests. Several clusters of ester QTLs associated with fruity aroma were discovered, such as QTLs for esters that share hexanoate group that were mapped in LG4A (Hexanoate_4A), those that share acetate and octyl groups in LG6A (Acetate_6A and Octyl_6A) or those with the same methyl group in LG7B (Methyl_7B). Different terpene QTLs associated with floral aroma appear grouped in a cluster in LG3C (Terpene_3C). Some of these clusters of QTLs were validated in a second F2 population, a cross of "Camarosa" and "Dover," that was also phenotyped for three years. Selected SNPs from floral and fruity aroma QTLs were tested in a third population, which will most likely be useful for marker-assisted breeding (MAB).

Transcriptomic and Metabolomic Analyses Provide Insights into the Formation of the Peach-like Aroma of Fragaria nilgerrensis Schlecht. Fruits

Fragaria nilgerrensis Schlecht. is a wild diploid strawberry species. The intense peach-like aroma of its fruits makes F. nilgerrensis an excellent resource for strawberry breeding programs aimed at enhancing flavors. However, the formation of the peach-like aroma of strawberry fruits has not been comprehensively characterized. In this study, fruit metabolome and transcriptome datasets for F. nilgerrensis (HA; peach-like aroma) and its interspecific hybrids PA (peach-like aroma) and NA (no peach-like aroma; control) were compared. In total, 150 differentially accumulated metabolites were detected. The K-means analysis revealed that esters/lactones, including acetic acid, octyl ester, δ-octalactone, and δ-decalactone, were more abundant in HA and PA than in NA. These metabolites may be important for the formation of the peach-like aroma of F. nilgerrensis fruits. The significantly enriched gene ontology terms assigned to the differentially expressed genes (DEGs) were fatty acid metabolic process and fatty acid biosynthetic process. Twenty-seven DEGs were predicted to be associated with ester and lactone biosynthesis, including AAT, LOX, AOS, FAD, AIM1, EH, FAH, ADH, and cytochrome P450 subfamily genes. Thirty-five transcription factor genes were predicted to be associated with aroma formation, including bHLH, MYB, bZIP, NAC, AP2, GATA, and TCPfamily members. Moreover, we identified differentially expressed FAD, AOS, and cytochrome P450 family genes and NAC, MYB, and AP2 transcription factor genes that were correlated with δ-octalactone and δ-decalactone. These findings provide key insights into the formation of the peach-like aroma of F. nilgerrensis fruits, with implications for the increased use of wild strawberry resources.

Red Fruits Composition and Their Health Benefits-A Review

The probability that fruit ingestion may protect human health is an intriguing vision and has been studied around the world. Therefore, fruits are universally promoted as healthy. Over the past few decades, the number of studies proposing a relationship between fruit intake and reduced risk of major chronic diseases has continued to grow. Fruits supply dietary fiber, and fiber intake is linked to a lower incidence of cardiovascular disease and obesity. Fruits also supply vitamins and minerals to the diet and are sources of phytochemicals that function as phytoestrogens, antioxidant and anti-inflammatory agents, and other protective mechanisms. So, this review aims to summarize recent knowledge and describe the most recent research regarding the health benefits of some selected red fruits.

Comparative Transcriptome Analysis to Identify Candidate Genes for FaRCg1 Conferring Resistance Against Colletotrichum gloeosporioides in Cultivated Strawberry (Fragaria × ananassa)

Colletotrichum crown rot (CCR) caused by Colletotrichum gloeosporioides is a serious threat to the cultivated strawberry (Fragaria × ananassa). Our previous study reported that a major locus, FaRCg1, increases resistance. However, the genomic structure of FaRCg1 and potential candidate genes associated with the resistance remained unknown. Here, we performed comparative transcriptome analyses of resistant 'Florida Elyana' and susceptible 'Strawberry Festival' after infection and identified candidate genes potentially involved in resistance. In 'Florida Elyana', 6,099 genes were differentially expressed in response to C. gloeosporioides. Gene ontology analysis showed that the most upregulated genes were functionally associated with signaling pathways of plant defense responses. Three genes in the genomic region of FaRCg1 were highly upregulated: a von Willebrand Factor A domain-containing protein, a subtilisin-like protease, and a TIFY 11A-like protein. Subgenome-specific markers developed for the candidate genes were tested with a diverse panel of 219 accessions from University of Florida and North Carolina State University breeding programs. Significant and positive associations were found between the high-resolution melting (HRM) marker genotypes and CCR phenotypes. These newly developed subgenome-specific functional markers for FaRCg1 can facilitate development of resistant varieties through marker-assisted selection.