Investigation of simple sequence repeats (SSR) markerassisted genetic diversity among upland Bt- and non Bt-cotton varieties

Abstract

Genetically modified with insect resistance gene (Cry1AC) and hybrid Bt-cotton genotypes were developed to redress cotton leaf curl virus epidemic. In this study, genetic diversity of 6 Bt- and 14 non- Bt upland cotton genotypes was detected using simple sequence repeats (SSR) or micro-satellite markers. Out of 31 primer pairs, only 7 (22.6%) yielded polymorphic amplicons of 80 to 340 bp. The average loci per primer were 3.16 and 78.6% of them were informative. The unweighed pair-group method with arithmetic averages (UPGMA) dendrogram placed Bt- and non-Bt cotton varieties into four major groups. With the exception of 4 accessions (being similar), genetic dissimilarity coefficient among all other genotypes ranged from 0.50 to 0.98 suggesting a wide genetic heterogeneity among the selected collection. The lowest similarity was found between BH-160 and CIM-482, CIM-496 and MNH- 554, BH-160 and CIM-473, SARMAST and BH-160 (non-Bt cultivars), respectively as were some Btcultivars. In contrast to previous reports, these results show that some Bt- and non-Bt-cotton cultivars form a genetically diverse population. They could be used in future breeding programmes to develop new elite cotton cultivars.

Key words: Bt-cotton, dissimilarity matrix, DNA polymorphism, genetic diversity, SSR marker.