Abstract
Cotton production in India by vast majority comes from cotton hybrids whose genetic purity is of great significance in seed production chain and trade. Therefore, there is need to develop a rapid, reliable and reproducible technique to assess the genetic purity of cotton hybrids as traditional, morphological traits-based ‘Grow-Out Test’ is resource intensive, time consuming, tedious and not an infallible procedure. In this regard, a study was planned to understand the genetic diversity among the hybrids and their parents, and also to identify SSR markers for confirmation of genetic purity or hybridity. One intra-arboreum hybrid, CICR2 (DS 5 GMS × LD 327 Sel.), four intra-hirsutum hybrids viz., CSHH198 (CSH 19 × CSH 8), CSHH238 (SH 2379 9Y × PIL 8 Sel.), CSHH243 (CSH 2013 × CSH 43), CSHH1862 (GMS 16A × CB 33) and one hirsutum × barbadense hybrid, Phule 388 (RHC-006 × RHCb-001) along with their respective parental lines were selected for molecular characterization. Of the total 215 SSR markers surveyed, 60 markers conveyed polymorphism. The information conveyed by the polymorphic SSR markers was utilized to assess the molecular divergence among the study material. Maximum genetic dissimilarity of 0.66 was noted between Phule 388 and LD 327 (Sel.), and between RHC-006 and DS 5 (GMS). Minimum genetic dissimilarity of 0.07 was observed between CSHH1862 with CB 33, followed by 0.11 between CICR2 with DS 5 (GMS). SSR markers were highly efficient in capturing both intra-species and inter-species level diversity. The clustering and factorial analysis was in congruence with the species of Gossypium. The diploid species genotypes were clustered separately and distinctly from the rest of the genotypes. All the hirsutum hybrids and their respective parents were found closely clustered. The inter-specific hybrid, Phule 388 along with its parents was found grouped closely. The genetic purity of the hybrids was confirmed using identified SSR markers [GH486, BNL1421, BNL3594, JESPR151 for G. hirsutum hybrid CSHH198; GH486, BNL2449, JESPR151, TMB0436 for G. hirsutum hybrid CSHH238; BNL2449, JESPR151, JESPR152 for G. hirsutum hybrid CSHH243; and, GH527, BNL3812, TMB1484, TMB1645, NAU1190, BNL3816 for inter-specific G. hirsutum × G. barbadense hybrid Phule 388]. The SSR markers were efficient in analysis of hybrid seed purity. The information generated in the present study about genetic diversity and genetic purity testing will greatly facilitate quality seed production of these cotton hybrids and thus, better cotton production.
New Hypervariable SSR Markers for Diversity Analysis, Hybrid Purity Testing and Trait Mapping in Pigeonpea [Cajanus cajan (L.) Millspaugh]