New Hypervariable SSR Markers for Diversity Analysis, Hybrid Purity Testing and Trait Mapping in Pigeonpea [Cajanus cajan (L.) Millspaugh]

Bohra, A and Jha, R and Pandey, G and Patil, P G and Saxena, R K and Singh, I P and Singh, D and Mishra, R K and Mishra, A and Singh, F and Varshney, R K and Singh, N P (2017) New Hypervariable SSR Markers for Diversity Analysis, Hybrid Purity Testing and Trait Mapping in Pigeonpea [Cajanus cajan (L.) Millspaugh]. Frontiers in Plant Science, 8 (377). pp. 1-15. ISSN 1664-462X

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Draft genome sequence in pigeonpea offers unprecedented opportunities for genomics assisted crop improvement via enabling access to genome-wide genetic markers. In the present study, 421 hypervariable simple sequence repeat (SSR) markers from the pigeonpea genome were screened on a panel of eight pigeonpea genotypes yielding marker validation and polymorphism percentages of 95.24 and 54.11%, respectively. The SSR marker assay uncovered a total of 570 alleles with three as an average number of alleles per marker. Similarly, the mean values for gene diversity and PIC were 0.44 and 0.37, respectively. The number of polymorphic markers ranged from 39 to 89 for different parental combinations. Further, 60 of these SSRs were assayed on 94 genotypes, and model based clustering using STRUCTURE resulted in the identification of the two subpopulations (K = 2). This remained in close agreement with the clustering patterns inferred from genetic distance (GD)-based approaches i.e., dendrogram, factorial and principal coordinate analysis (PCoA). The AMOVA accounted majority of the genetic variation within groups (89%) in comparison to the variation existing between the groups (11%). A subset of these markers was implicated for hybrid purity testing. We also demonstrated utility of these SSR markers in trait mapping through association and bi-parental linkage analyses. The general linear (GLM) and mixed linear (MLM) models both detected a single SSR marker (CcGM03681) with R2 = 16.4 as associated with the resistance to Fusarium wilt variant 2. Similarly, by using SSR data in a segregating backcross population, the corresponding restorer-of-fertility (Rf) locus was putatively mapped at 39 cM with the marker CcGM08896. However, The marker-trait associations (MTAs) detected here represent a very preliminary type and hence demand deeper investigations for conclusive evidence. Given their ability to reveal polymorphism in simple agarose gels, the hypervariable SSRs are valuable genomic resource for pigeonpea research community, particularly in South Asia and East Africa where pigeonpea is primarily grown.

Item Type: Article
Divisions: Research Program : Genetic Gains
CRP: CGIAR Research Program on Grain Legumes
Uncontrolled Keywords: Pigeonpea, SSR, diversity, hybrid, polymorphism, genome, genetic diversity, population structure analysis, genetic analysis
Subjects: Mandate crops > Pigeonpea
Others > Genetics and Genomics
Depositing User: Mr Ramesh K
Date Deposited: 13 Apr 2017 05:14
Last Modified: 18 Apr 2017 06:01
Official URL:
Acknowledgement: Authors acknowledge support from “CRP on hybrid technology” and “Genetic improvement of yield and disease resistance in short duration pigeonpea” schemes of Indian Council of Agricultural Research (ICAR), New Delhi, India.
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