Study of genetic divergence through D2 analysis and molecular marker techniques in cowpea (Vigna unguiculata L. Walp)

Abstract

The present experiment was conducted during summer 2016 for study of genetic diversity in 40 different genotypes of cowpea using D2 statistics method of Mahalanobis andMolecular marker techniques. The fourty genotypes of cowpea were grouped into seven clusters following Tocher’s method (Rao, 1952) which indicate the presence of diversity for different traits under study. The results indicate that a maximum number of genotypes appeared in cluster I (10 genotypes) followed by cluster V (9 genotypes), cluster III (7 genotypes), cluster VII (6 genotypes), cluster II and VI (3 genotypes) and cluster IV (2 genotypes). The maximum intra-cluster distance was recorded within cluster I (7.39) and the maximum inter-cluster distance between cluster VI and VII (D=19.83), indicating the existence of wide genetic variability. Based on mean performances, cluster IV and cluster II found superior for yield and yield contributing characters. Therefore genotypes selected for hybridization among the above said clusters would produce high heterosis and segregant for more than one economic character.The genomic DNA of 40 genotypes of cowpea was extracted by modified CTAB method for the molecular characterization through ISSR markers. Total 30 ISSR primers were screened across all the genotypes of cowpea. Out of 30 primers seven primers produce polymorphic band with an average of 1.13 bands per primer. The average polymorphism detected by the ISSR band in the present investigation was 97.14% with 0.756 average Polymorphic Information Content (PIC).The dendrogram, based on Jaccard’s similarity co-efficient was able to classify all the genotypes of cowpea in two clusters. Among the cowpea genotypes GC-5 and Pusa-falguni evident maximum similarity; while the genotypes GP-761 and GP-452 shown minimum similarity.