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GENETIC DISSIMILARITIES IN COWPEA (VIGNA UNGUICULATA (L.) WALP.) FOR PROTEIN PEPTIDES AND THEIR SIGNIFICANCE FOR QUANTITATIVE TRAITS LOCI

MUHAMMAD SAJJAD IQBAL, ABDUL GHAFOOR*, AFSARI SHARIF QURESHI AND ZAHOOR AHMAD*

Abstract: Cowpea (Vigna unguiculata (L.) Walp.), gemplasm comprising of diverse 138 accessions was evaluated for 23 physiological and agronomic characters during summer 2000 at NARC, Islamabad. The same material was analyzed for total seed protein using Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Out of 40 protein subunits, 31 were polymorphic and 9 were monomorphic. Out of polymorphic bands, 23 were observed significant for various quantitative trait loci. SDS-PAGE provided a tool for germplasm discrimination based on genetic differences in seed storage protein comparison in cowpea. The factors affecting quantitative traits may occur as individual genes or gene clusters scattered throughout the genome, therefore, quantitative traits were expected differently at several loci. Variation in 17 quantitative traits (root weight, branches, chlorophyll contents, pods plant^-I, leaf area trifoliate^-1, plant height, root length, biological yield^-1, seeds pod^-1, number of locules^-1, seed set percentage, grain yield^-1, harvest index, 100-seed weight, seed length, seed width and pod width) was significantly associated with various protein sub-units, however, the actual number of QTLs could be fewer because several of these traits were correlated. Variation at protein peptides in the vicinity of QTLs may be an indication of genetic variation potentially available to breeding programmes for improving yield potential. Expansion of genetic base for cowpea breeding might be accomplished by systematic use of germplasm that differ from common banding pattern and are known to be associated with variation in quantitative traits.

Department of Biological Sciences, Quaid-I-Azam University, Islamabad, Pakistan.

Institute of Agro Biotechnology & Genetic Resources (IABGR), National Agricultural Research Center (NARC), Islamabad, Pakistan.