Assessment of genetic diversity among Indian potato (Solanum tuberosum L.) collection using microsatellite and retrotransposon based marker systems

Revisiting the ethnomedicinal, ethnopharmacological, phytoconstituents and phytoremediation of the plant Solanum viarum Dunal

Solanum viarum, a perennial shrub, belongs to the family Solanaceae known for its therapeutic value worldwide. As a beneficial remedial plant, it is used for treating several disorders like dysentery, diabetes, inflammation, and respiratory disorders. Phytochemistry studies of this plant have shown the presence of steroidal glycoside alkaloids, including solasonine, solasodine, and solamargine. It also has flavonoids, saponins, minerals, and other substances. S. viarum extracts and compounds possess a variety of pharmacological effects, including antipyretic, antioxidant, antibacterial, insecticidal, analgesic, and anticancer activity. Most of the heavy metals accumulate in the aerial sections of the plant which is considered a potential phytoremediation, a highly effective method for the treatment of metal-polluted soils. We emphasize the forgoing outline of S. viarum, as well as its ethnomedicinal and ethnopharmacological applications, the chemistry of its secondary metabolites, and heavy metal toxicity. In addition to describing the antitumor activity of compounds and their mechanisms of action isolated from S. viarum, liabilities are also explained and illustrated, including any significant chemical or metabolic stability and toxicity risks. A comprehensive list of information was compiled from Science Direct, PubMed, Google Scholar, and Web of Science using different key phrases (traditional use, ethnomedicinal plants, western Himalaya, Himachal Pradesh, S viarum, and biological activity). According to the findings of this study, we hope that this review will inspire further studies along the drug discovery pathway of the chemicals extracted from the plant of S. viarum. Further, this review shows that ethnopharmacological information from ethnomedicinal plants can be a promising approach to drug discovery for cancer and diabetes.

Transposable elements: multifunctional players in the plant genome

Transposable elements (TEs) are indispensable components of eukaryotic genomes that play diverse roles in gene regulation, recombination, and environmental adaptation. Their ability to mobilize within the genome leads to gene expression and DNA structure changes. TEs serve as valuable markers for genetic and evolutionary studies and facilitate genetic mapping and phylogenetic analysis. They also provide insight into how organisms adapt to a changing environment by promoting gene rearrangements that lead to new gene combinations. These repetitive sequences significantly impact genome structure, function and evolution. This review takes a comprehensive look at TEs and their applications in biotechnology, particularly in the context of plant biology, where they are now considered "genomic gold" due to their extensive functionalities. The article addresses various aspects of TEs in plant development, including their structure, epigenetic regulation, evolutionary patterns, and their use in gene editing and plant molecular markers. The goal is to systematically understand TEs and shed light on their diverse roles in plant biology.

Molecular insights into the genetic diversity and population structure of Artemisia annua L. as revealed by insertional polymorphisms

The knowledge about the level of genetic diversity and population structure in natural populations of Artemisia annua L. is a primary step in breeding programs for development of new cultivars with higher artemisinin level and better quality of secondary metabolites composition. We used PCR-based "retrotransposon-microsatellite amplified polymorphisms" (REMAPs) to study insertional polymorphism in A. annua genome to assess genetic variability and population structure in a collection of 118 accessions collected from north and northwest of Iran. Twenty-five primer combinations of 10 retrotransposon and seven ISSR primers amplified a total of 693 clear and unambiguous fragments in the studied accessions. The average number of bands, polymorphic bands, polymorphism, effective number of alleles, Shannon's information index and expected heterozygosity were 27.72, 24.76, 88.14%, 1.47, 0.42 and 0.28, respectively. The analysis of molecular variance revealed high genetic variation present within sampled geographical regions. Distance-based cluster analysis assigned the studied accessions into four clusters according to their geographical origin, which were also confirmed by principal coordinate analysis. In model-based Bayesian clustering, the maximum value of Δk was obtained when the collection of 118 assayed A. annua accessions assigned into two subgroups (K = 2). The results showed the high genetic variation in the collection of Iranian sweet wormwood which revealed by REMAP markers indicating the reliability and efficiency of this marker system for analysis of genetic diversity and population structure of A. annua.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40415-022-00860-x.

TEMM: A Curated Data Resource for Transposon Element-Based Molecular Markers in Plants

Transposon elements (TEs) are mobile genetic elements that can insert themselves into new locations and modify the plant genome. In recent years, they have been used as molecular markers in plant breeding programs. TE-based molecular markers (TE-markers) are divided into two categories depending on the transcription mechanism of the TEs. The first category is retrotransposon-based molecular markers, which include RBIP, IRAP, REMAP, and iPBS. The second group is DNA-based-TE-markers, which include MITE, TE-junction, and CACTA TE-markers. These markers are a good tool for studying genetic diversity and can provide information on plants' phylogenetic and evolutionary history. They can help improve breeding programs to increase agronomic traits and develop new varieties. Overall, TE-markers play an important role in plant genetics and plant breeding and contribute to a better understanding of plant biology. Here, we present TEMM, a curated data resource for TE-markers in plants. Relevant research articles were screened to collect primer sequences and related information. Only articles containing primer sequences are added to the present data resource. TEMM contains 784 primers with their associated PCR reaction programs and their applications in various crops. These include 203 IPBS, 191 RBIP, 140 IRAP, 78 TE-junction, 76 IRAPS, 47 RBIP-IRAP, 16 IRAP-REMAP, 12 REMAP, 12 REMA-IRAP, 6 REMA, and 3 ISBP primers. The data resource is freely available at https://bioinformatics.um6p.ma/TEMM .

Retrotransposons: How the continuous evolutionary front shapes plant genomes for response to heat stress

Long terminal repeat retrotransposons (LTR retrotransposons) are the most abundant group of mobile genetic elements in eukaryotic genomes and are essential in organizing genomic architecture and phenotypic variations. The diverse families of retrotransposons are related to retroviruses. As retrotransposable elements are dispersed and ubiquitous, their "copy-out and paste-in" life cycle of replicative transposition leads to new genome insertions without the excision of the original element. The overall structure of retrotransposons and the domains responsible for the various phases of their replication is highly conserved in all eukaryotes. The two major superfamilies of LTR retrotransposons, Ty1/Copia and Ty3/Gypsy, are distinguished and dispersed across the chromosomes of higher plants. Members of these superfamilies can increase in copy number and are often activated by various biotic and abiotic stresses due to retrotransposition bursts. LTR retrotransposons are important drivers of species diversity and exhibit great variety in structure, size, and mechanisms of transposition, making them important putative actors in genome evolution. Additionally, LTR retrotransposons influence the gene expression patterns of adjacent genes by modulating potential small interfering RNA (siRNA) and RNA-directed DNA methylation (RdDM) pathways. Furthermore, comparative and evolutionary analysis of the most important crop genome sequences and advanced technologies have elucidated the epigenetics and structural and functional modifications driven by LTR retrotransposon during speciation. However, mechanistic insights into LTR retrotransposons remain obscure in plant development due to a lack of advancement in high throughput technologies. In this review, we focus on the key role of LTR retrotransposons response in plants during heat stress, the role of centromeric LTR retrotransposons, and the role of LTR retrotransposon markers in genome expression and evolution.

Hybridization and polyploidization effects on LTR-retrotransposon activation in potato genome

Hybridization and polyploidization are major forces in plant evolution and potatoes are not an exception. It is proposed that the proliferation of Long Terminal Repeat-retrotransposons (LTR-RT) is related to genome reorganization caused by hybridization and/or polyploidization. The main purpose of the present work was to evaluate the effect of interspecific hybridization and polyploidization on the activation of LTR-RT. We evaluated the proliferation of putative active LTR-RT in a diploid hybrid between the cultivated potato Solanum tuberosum and the wild diploid potato species S. kurtzianum, allotetraploid lines derived from this interspecific hybrid and S. kurtzianum autotetraploid lines (ktz-autotetraploid) using the S-SAP (sequence-specific amplified polymorphism) technique and normalized copy number determination by qPCR. Twenty-nine LTR-RT copies were activated in the hybrid and present in the allotetraploid lines. Major LTR-RT activity was detected in Copia-27, Copia-12, Copia-14 and, Gypsy-22. According to our results, LTR-RT copies were activated principally in the hybrid, there was no activation in allotetraploid lines and only one copy was activated in the autotetraploid.

Late Blight Resistance Evaluation and Genome-Wide Assessment of Genetic Diversity in Wild and Cultivated Potato Species

Late blight, caused by the oomycete Phytophthora infestans, is the most devastating disease in potato-producing regions of the world. Cultivation of resistant varieties is the most effective and environmentally friendly way to control potato late blight disease, and identification of germplasms with late blight resistance and clarification their genetic relationship would promote the development of the resistant varieties. In this study, a diverse population of 189 genotypes with potential late blight resistance, consisting of 20 wild species and cultivated Solanum tuberosum Andigenum group and Chilotanum group, was screened for the presence of late blight resistance by performing challenge inoculation with four Phytophthora infestans isolates including one 13_A2 isolate, CN152. Ten elite resources with broad-spectrum resistance and 127 with isolate-specific resistance against P. infestans were identified. To improve the available gene pool for future potato breeding programs, the population was genotyped using 30 simple sequence repeat (SSR) markers covering the entire potato genome. A total of 173 alleles were detected with an average of 5.77 alleles per locus. Structure analysis discriminated the 189 potato genotypes into five populations based on taxonomic classification and genetic origin with some deviations. There was no obvious clustering by country of origin, ploidy level, EBN (endosperm balance number) value, or nuclear clade. Analysis of molecular variance showed 10.08% genetic variation existed among populations. The genetic differentiation (Fst) ranged from 0.0937 to 0.1764, and the nucleotide diversity (π) was 0.2269 across populations with the range from 0.1942 to 0.2489. Further genotyping of 20K SNP array confirmed the classification of SSRs and could uncover the genetic relationships of Solanum germplasms. Our results indicate that there exits abundant genetic variation in wild and cultivated potato germplasms, while the cultivated S. tuberosum Chilotanum group has lower genetic diversity. The phenotypic and genetic information obtained in this study provide a useful guide for hybrid combination and resistance introgression from wild gene pool into cultivated species for cultivar improvement, as well as for germplasm conservation efforts and resistance gene mining.

Developing Transposable Element Marker System for Molecular Breeding

Transposable element (TE) marker system was developed considering the useful properties of the transposable elements such as their large number in the animal and plant genomes, high rate of insertion polymorphism, and ease of detection. Various methods have been employed for developing a large number of TE markers in several crop plants for genomics studies. Here we describe some of these methods including the recent whole genome search. We also review the application of TE markers in molecular breeding.

Simple sequence repeat analysis of new potato varieties developed in Alberta, Canada

The worldwide demand for potato production requires the constant development of new potato varieties with improved yield, quality, disease resistance, and abiotic tolerance. However, cultivar registration is preceded by a long process to morphologically and physiologically characterize the plants. Notably, this process can be expedited by DNA marker analysis. Simple sequence repeats (SSRs), also known as microsatellites, are the most common reliable DNA markers used to discriminate between genotypes. In this study, 20 potato varieties, including five new genotypes developed in Alberta, Canada, were fingerprinted using 10 SSR markers selected for their high discriminatory power. Different SSRs were amplified from potato DNA using specific primers, and the DNA fragment sizes were analyzed by denaturing polyacrylamide gel electrophoresis. The number of alleles per locus ranged from two for the SSR marker STPoAc58 to six for STM0030 and STM0037 with an average of 4.4. In addition, a total of 77 unique patterns were observed for the 10 SSR markers. The polymorphic information content ranged from 0.477 to 0.802 with an average of 0.675 per locus. In this study, STM0037, STM1016, and STM1104 were found to be the best SSR markers to detect genetic differences between potato varieties. A minimum of two markers was required to distinguish between all 20 genotypes. Most importantly, this highly informative molecular tool confirmed that the developed potato varieties were genetically different from their respective maternal lines and potentially constituted new cultivars.

Analysis of genetic diversity in pigeon pea germplasm using retrotransposon-based molecular markers

Pigeon pea (Cajanus cajan), an important legume crop is predominantly cultivated in tropical and subtropical regions of Asia and Africa. It is normally considered to have a low degree of genetic diversity, an impediment in undertaking crop improvement programmes.We have analysed genetic polymorphism of domesticated pigeon pea germplasm (47 accessions) across the world using earlier characterized panzee retrotransposon-based molecularmarkers. Itwas conjectured that since retrotransposons are interspersed throughout the genome, retroelements-based markers would be able to uncover polymorphism possibly inherent in the diversity of retroelement sequences. Two PCR-based techniques, sequence-specific amplified polymorphism (SSAP) and retrotransposon microsatellite amplified polymorphism (REMAP) were utilized for the analyses.We show that a considerable degree of polymorphism could be detected using these techniques. Three primer combinations in SSAP generated 297 amplified products across 47 accessions with an average of 99 amplicons per assay. Degree of polymorphism varied from 84-95%. In the REMAP assays, the number of amplicons was much less but up to 73% polymorphism could be detected. On the basis of similarity coefficients, dendrograms were constructed. The results demonstrate that the retrotransposon-based markers could serve as a better alternative for the assessment of genetic diversity in crops with apparent low genetic base.

Genetic diversity and association mapping in the Colombian Central Collection of Solanum tuberosum L. Andigenum group using SNPs markers

The potato (Solanum tuberosum L.) is the fourth most important crop food in the world and Colombia has one of the most important collections of potato germplasm in the world (the Colombian Central Collection-CCC). Little is known about its potential as a source of genetic diversity for molecular breeding programs. In this study, we analyzed 809 Andigenum group accessions from the CCC using 5968 SNPs to determine: 1) the genetic diversity and population structure of the Andigenum germplasm and 2) the usefulness of this collection to map qualitative traits across the potato genome. The genetic structure analysis based on principal components, cluster analyses, and Bayesian inference revealed that the CCC can be subdivided into two main groups associated with their ploidy level: Phureja (diploid) and Andigena (tetraploid). The Andigena population was more genetically diverse but less genetically substructured than the Phureja population (three vs. five subpopulations, respectively). The association mapping analysis of qualitative morphological data using 4666 SNPs showed 23 markers significantly associated with nine morphological traits. The present study showed that the CCC is a highly diverse germplasm collection genetically and phenotypically, useful to implement association mapping in order to identify genes related to traits of interest and to assist future potato genetic breeding programs.

Assessment of genetic diversity in Nordic timothy (Phleum pratense L.)

BACKGROUND

Timothy (Phleum pratense L.), a cool-season hexaploid perennial, is the most important forage grass species in Nordic countries. Earlier analyses of genetic diversity in a collection of 96 genebank accessions of timothy with SSR markers demonstrated high levels of diversity but could not resolve population structure. Therefore, we examined a subset of 51 accessions with REMAP markers, which are based on retrotransposons, and compared the diversity results with those obtained with SSR markers.

RESULTS

Using four primer combinations, 533 REMAP markers were analyzed, compared with 464 polymorphic alleles in the 13 SSR loci previously. The average marker index, which describes information obtained per experiment (per primer combination or locus) was over six times higher with REMAPs. Most of the variation found was within accessions, with somewhat less, 89 %, for REMAPs, than for SSR, with 93 %.

CONCLUSIONS

SSRs revealed differences in the level of diversity slightly better than REMAPs but neither marker type could reveal any clear clustering of accessions based on countries, vegetation zones, or different cultivar types. In our study, reliable evaluation of SSR allele dosages was not possible, so each allele had to be handled as a dominant marker. SSR and REMAP, which report from different mechanisms of generating genetic diversity and from different genomic regions, together indicate a lack of population structure. Taken together, this likely reflects the outcrossing and hexaploid nature of timothy rather than failures of either marker system.

Use of SSR and retrotransposon-based markers to interpret the population structure of native grapevines from southern Italy

Native grapevines are the quintessential elements of Southern Italy winemaking, and genomic characterization plays a role of primary importance for preservation and sustainable use of these unexploited genetic resources. Among the various molecular techniques available, SSR and retrotransposons-based markers result to be the most valuable for cultivars and biotypes distinctiveness. A total of 62 accessions including 38 local grape cultivars were analyzed with 30 SSR, four REMAP and one IRAP markers to assess their genetic diversity and obtain a complete genomic profiling. The use of VrZAG79, VrZAG112, VVS2, VVMD25 and VVMD5 combined with retrotransposon-based markers proved to be the most discriminating and polymorphic markers for the rapid and unambiguous identification of minority grapevines from Campania region, which is considered one of the most appreciated Italian districts for wine production. Results revealed 58 SSR marker-specific alleles, 22 genotype-specific SSR alleles, and four REMAP and IRAP private bands. Cases of synonymy and homonymy were discovered. In conclusion, we provided evidences that the integrating SSR and retrotransposon-based markers is an effective strategy to assess the genetic diversity of autochthonous grapes, allowing their easy identification.