Morpho-molecular characterization of cluster bean(cyamopsis tetragonoloba(L.) taub.)
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Date
2011
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College of Agriculture, Vellayani
Abstract
The present study entitled “ Morpho- molecular characterization of cluster bean [Cyamopsis tetragonoloba (L.) Taub.] was conducted at the Departments of Olericulture and Plant Biotechnology, College of Agriculture, Vellayani during 2010-2011. The objectives were to assess the genetic diversity of the cluster bean germplasm both at morphological and molecular level. One hundred genotypes of cluster bean were evaluated for yield and yield related characters in randomised block design with two replications. Analysis of variance revealed significant differences for fourteen out of sixteen characters studied. The significant characters include plant height, primary branches, internodal length, pod clusters per plant, pods per plant, pods per cluster, yield per plant, pod weight, pod length, pod girth, seeds per pod, 100 seed weight, protein content and shelf life High vales of PCV and GCV were recorded for primary branches followed by pod weight, yield per plant, pods per cluster and pod clusters per plant. High heritability coupled with high genetic gain was observed for primary branches, clusters per plant, pods per cluster, yield, pod weight, pod length and pod girth. Vegetable pod yield showed high positive genotypic correlation with the characters pod weight, pod length, pod girth, pods per plant, plant height, pod clusters per plant and 100 seed weight. Plant height, pods per plant and pod length showed positive direct effect on yield. In genetic divergence analysis 100 accessions were grouped into five clusters. Maximum number of genotypes were in cluster I and most of the genotypes in this cluster were low yielders. The highest yielders stood in the fifth cluster. On the basis of selection index CT 72 (a local collection from Tamil Nadu) recorded highest index value followed by Pusa Naubahar and CT 81 (a local collection from Tamil Nadu). These were identified as genetically superior. In molecular characterization, 12 accessions were selected from different clusters formed by morphological analysis. Out of thirty primers screened, eleven primers viz., OPA-14, E-14, E-15, E-1, E-3, OPA-9, E-4, OPB-8, OPP-16, E-12, E-6 were selected for DNA amplification. They generated 62 scorable bands out of which 41 were polymorphic and 21 monomorphic showing 66.12 per cent polymorphism. Resulted amplified products ranged in the size of 100- 1200 bp. The similarity coefficient values ranged from 0.375 to 0.894. At 0.73 per cent similarity level, 12 accessions were divided into 5 clusters. CT 22 constituted first cluster, CT 41 and CT 60 in second, CT 12 and CT 17 in third, CT 8 and CT 27 were included in fourth and CT 3, CT 79, CT 38 and CT 81 and CT 72 in fifth. CT 79 and CT 38 showed maximum relatedness with each other. The accessions CT 17 and CT 12 and CT 38, CT 81 and CT 72 were closely placed in dendrograms generated by both morphological and molecular analysis. Clustering of other accessions used in the molecular study was not in full agreement with the morphological clustering pattern. This may be due to the influence of environment in modifying the expression of characters. The present study using morphological characters and RAPD markers have shown considerable variability in cluster bean genotypes. Two local accessions viz., CT 72 (non branching type) and CT 81 (branching type) were identified as superior for yield and quality. These genotypes may be progressed to further confirmatory studies, CYT and multilocational trials. The study also revealed the reliability of molecular techniques compared to morphological methods in the characterization of cluster bean. Further studies on morphological and agronomic traits and analysis of accessions with more number of primers and reliable DNA markers may be helpful in getting accurate result.
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