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Jomo Kenyatta University of Agriculture and Technology (2006)

Genetic diversity in pigeonpea (Cajanus cajan L.millsp.) landrace as revealed by simple sequence repeat markers

Songok, Serah Chepchirchir

Titre : Genetic diversity in pigeonpea (Cajanus cajan L.millsp.) landrace as revealed by simple sequence repeat markers

Auteur : Songok, Serah Chepchirchir

Université de soutenance : Jomo Kenyatta University of Agriculture and Technology, Kenya

Grade : Master of Science (MS) 2006

Résumé
Genetic relationships among 88 pigeonpea [Cajanus cajan (L.) Millsp] accessions that originated from different countries and that are part of the germplasm collections of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) were evaluated using six microsatellite markers. A total of 48 alleles were detected in the populations studied, with a mean value of eight alleles per locus. Nei’s unbiased estimate of gene diversity and observed heterozygosity (direct count) were 0.489 and 0.142 on average respectively leading to positive values of the Wright’s fixation indexes in all the populations studied. Allele frequencies were calculated and used for the characterization of the landrace accessions and study of their genetic relationships. Genetic distances were calculated based on Roger’s modified distance and used to construct UPGMA dendrograms. The closest populations were landrace accessions from Kenya and Tanzania while most divergent were landrace accessions from Uganda and Gujarat. A high level of differentiation was observed between states/countries compared to between India and East Africa. Highest differentiation was observed at within accession. Based on this genetic study, we propose some appropriate strategies for conservation by rescuing and conserving core populations for in situ conservation and sampling preserving more populations with fewer individuals from each population for ex situ conservation. For in situ conservation, Maharashtra and Tamil Nadu populations should be rescued and conserved as core populations harboring a significant amount of genetic diversity. A program of ex situ conservation that samples intensively from within all accessions to fulfill the objective of capturing most of the genetic variability as most of the genetic variation is between individuals within an accession.

Mots Clés  : Cajanus cajan / Pigeon peas USE Cajanus cajan / Genetics

Présentation (Research Kenya)

Page publiée le 22 septembre 2010, mise à jour le 24 février 2018