ASSESSMENT OF GENETIC-VARIABILITY IN HEXAPLOID WHEAT LANDRACES OF PAKISTAN BASED ON POLYMORPHISM FOR HMW GLUTENIN SUBUNITS

Sixty hexaploid wheat landraces collected from five regions of Pakista n were assessed for genetic variability in terms of high molecular wei ght (HMW) glutenin subunits as revealed by SDS-PAGE. The germplasm app eared to be diverse and unique on the basis of HMW glutenin subunit co mpositions. Out of 24 alleles detected at all the Glu-l loci, four bel onged to Glu-Al, 12 to Glu-BI and eight to Glu-DI locus. The number of novel HMW glutenin subunits detected were 1, 4 and 6 at the three loc i (Glu-Al, Glu-BI, Glu-DI), respectively. The frequency distribution p atterns of 24 allelic variants detected at the three Glu-l loci in 108 0 samples analysed for 60 accessions were determined both on the basis of individual accessions and on the basis of regions (accessions pool ed across the regions). One allele (''null'') at the Glu-Al locus, thr ee alleles (17 + 18, 7 + 8, 14) at the Glu-Bl locus and, two alleles ( 2 + 12 and 2* + 12') at the Glu-DI locus were found most frequently d istributed in the 60 populations. Maximum variation was observed in th e Baluchistan and Gilgit regions of Pakistan in terms of distribution of novel Glu-l alleles. A higher gene diversity was observed between t he populations as compared to the gene diversity within the population s while, a reverse pattern of gene diversity was observed when populat ions were pooled across the regions (higher within the regions than be tween the regions). A data base has been generated in this study which could be expanded and usefully exploited for cultivar development or management of gene bank accessions.