CHARACTERIZATION OF COWPEA (Vigna Unguiculata L.) GENOTYPES THROUGH MOLECULAR AND BIOCHEMICAL MARKERS
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Date
2012-04
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jau,junagadh
Abstract
Cowpea (Vigna unguiculata L.) vegetable plays a vital role in the health and nutritional security of human being and it belongs to the family of fabaceae, is a diploid with chromosome number 2n=22 and genome size is 600 Mb. Cowpea is one of the oldest source of human food. It is grown in tropic and sub tropic regions of Asia, Africa, Central and Southern America, parts of southern Europe and USA, India and Ethiopia as primary center of origin of cowpea and China as a secondary center of origin. Though India constitutes one of the main centers of diversity, the historical as most probable place of origin of cowpea’s non-specific wild forms are found in Africa. Morphological, cowpea seeds colours are very different. This crop showed a high level of morphological diversity which results in confusion about its systematics and this diversity is at the level of genera, species and cultivars.
The aims of the studies reported in this thesis were to characterize cowpea genotypes with different morphological, molecular and biochemical tools. To reveal characterization among ten cowpea genotypes, three different morphological characters were recorded [100 seeds weight, seeds size and seeds colour]. In that, the maximum seed weight was observed in JCPL-99 (14.65g) with large seed size and reddish brown colour, while minimum seed weight was observed in JCP-96-24-2(8.41g) with small seed size and white colour with brown spots.
The RAPD, ISSR and SSR marker systems were applied to the cowpea genotypes. For the RAPD data, based on PIC value, it can be said that primer OPD-08 was the best primer resulting in good amplification with maximum PIC value (0.923). Dendrogram constructed using the RAPD data clearly distinguished all genotypes. It revealed that JCPL-99 and JCPL-116 found in one cluster and shared maximum 81.00% similarity; however, genotype JCPL-2 have out grouped from other 9 genotypes and shared minimum 60.00% similarity. In case of ISSR data, based on PIC value it can be said that the primer 834 was the best primer resulting in good amplification with maximum PIC value (0.890). Jaccard’s similarity coefficient ranged from 0.612 and 0.890. The ISSR results indicated that maximum similarity of 92.90% was found between JCPL-116 and JCPL-118, while minimum similarity of 68.40% was obtained between JCPL-2 and JCP-96-3-2-1. For the SSR data, based on PIC value it can be said that the primer VM-11 was the best primer resulting in good amplification with maximum PIC value (0.905). Jaccard’s similarity coefficient ranged from 0.333 to 0.627. SSR data revealed that JCPL-116 showed maximum variability compared to other nine genotypes. The combined RAPD, ISSR and SSR analysis revealed that out of ten genotypes JCPL-48 and JCPL-52 showed maximum (78.10%) similarity. The lowest similarity of 61.20% was found between JCPL-2 and JCP-96-3-2-1. The JCPL-2 genotype was medium in size i.e. 14.19 g of 100 seeds weight with yellowish white colour. This genotype was found alone in most clustering pattern with other 9 genotypes.
For the biochemical markers, the isoenzymes; peroxidase, esterase, polyphenol oxidase and superoxide dismutase and protein profiling were used to know the electrophoretic banding patterns of ten different cowpea genotypes by NATIVE-PAGE.
A total of six alleles were generated by peroxidase isozymes at eight DAG. Relative mobility was varied between 0.160-0.735 with 17.67% polymorphism. The total nine bands of esterase isozymes were observed having 0.169-0.797 relative mobility with 33.33% polymorphism. In case of polyphenol oxidase isozymes, total seven bands were observed having relative mobility of 0.165-0.756 with 28.57% polymorphism. Total four bands of superoxide dismutase isozymes were observed having relative mobility between 0.202-0.414, while protein profiling showed relative mobility of total 10 bands in the range of 0.366 to 0.920 with 10% polymorphism. Combined analysis of isoenzymes and protein profiling revealed that the genotype JCPl-2 and JCPL-52 had minimum similarity [82.80%]. Combined analysis of isoenzymes revealed that the genotype JCPl-52 and JCPL-118 had minimum similarity of [76.90%].
It was evident from present study that isoenzymes and molecular markers were proficient to distinguish ten cowpea genotypes.
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Biotechnology