Browsing by Author "S, PAVITHRA B"
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ThesisItem Open Access Molecular characterization and validation of microsatellite markers linked with tolerance to Powdery Mildew disease in mungbean (Vigna radiata (L.) Wilczek)(Orissa University of Agriculture and Technology, Bhubaneswar, 2018) S, PAVITHRA B; Samal, Kailas ChandraMungbean (Vigna radiata L. Wilczek) is a self-pollinated diploid grain legume (2n=2x=22) crop and has genome size of 560 mb. It is the most important legume (Pulse) crop after Chickpea and Pigeon pea in India and widely cultivated in different parts of India as it is well adapted to multiple cropping systems in the drier and warmer climates.The yield of mungbean in India was 30.41 lakh hectares with a total production of 14.24 lakh tonnes and Odisha in particular is very low productivity (337 kg/ha) mainly due to inherent genotype failures and losses due to pests and diseases. On account of its dense crop canopy, photo insensitivity, and short duration, it assumes special significance in crop diversification, intensification, and conservation of natural resources and sustainability of production systems. Many diseases affect mungbean, among which Powdery mildew disease in mungbean caused by Erisyphe polygoni is economically important and it reduces photosynthetic activity and physiological changes which results in 20-40 per cent reduction in yield. For achieving a gain in yield and for developing resistant and well adoptable genotypes through breeding programme, scientific collection, characterisation and evaluation of mungbean germplasm is highly essential. It also helps proper identification of genotypes with the desired characteristics. The objective of the present study was to describe the nature and extent of genotypic variation among mungbean collections for a range of traits of potential agronomic and adaptive interests. A total of 27 mungbean genotypes along with four check varieties viz. ‘Kamdev’, ‘OBBGG-52’, ‘IPM-02-14’ and ‘IPM-02-3’,wereevaluated for several diverse traits for two cropping seasons at two different locations in Odisha. Analysis of data on classification of visual character and various categorical DUS descriptors revealed the occurrence of 62 numbers of variants out of which eighteen variants could not be observed in any of the genotype. Seed colour was observed in different states of colour like yellow, green, mottled and black exhibited in 9.67%, 41.93%, 29.03%, 19.35% genotypes respectively. Majority of genotypes (22.58%) were highly resistant for powdery mildew and 16.12% were resistant to powdery mildew. While 19.35% genotypes exhibited were highly susceptible, with moderate resistance and susceptible. Among all genotypes 3.3%vgenotypes were exhibited susceptible to powdery mildew. The cluster analysis revealed wide diversity in the mungbean collection. The genotype pairs ‘Badahana Local’ and ‘Hinjili Local’, showed the maximum dissimilarity (2.67) followed by dissimilarity between ‘OBGG-52’ and ‘Berhampur Local 1’ among the thirty one genotypes, whereas, ‘Nayagarh Local’ and ‘Nayagarh Local 6’ showed lowest dissimilarity (0.01) followed by dissimilarity between ‘Kukudakhandi Local’ and ‘Banpur Local’(0.20).The genetic dis-similarity matrix was analysed using UPGMA clustering algorithms for the construction of dendrogram and the analysis revealed four main clusters at 8.75 dis-similarity coefficient with best possible discrimination between groups. Fourteen genotypes were included in Cluster I whereas cluster-II was represented by only one genotype (‘Sambalpur Local 2’). Ten genotypes were represented in the Cluster III and cluster IV had 6 genotypes. At 8.07 dis-similarity coefficient, Cluster-I was further subdivided into two sub-clusters. The sub-cluster I A was represented by two genotypes and subcluster IB had 12 genotypes. In the present study analyzed seven molecular markers viz., VrCSSTS1, VrCSSTS2, VrCSSSR3, CEDG191, MB-SSR238, CEDG166, CEDG282 were found associated with powdery mildew resistance in mungbean genotypes studied. The VrCSSSR and VrCSSTS marker linked with powdery mildew resistance gene were tested in different genotypes with known powdery mildew reaction and the results showed consistent association of the marker in all the powdery mildew resistant genotypes and absent in all the powdery mildewsusceptible genotypes. The results confirmed the validation of these markers with powdery mildew resistance gene in different genetic back-grounds. Similarly, CEDG191, CEDG166, CEDG282 reported to be linked to powdery mildew resistance amplified the respective marker fragment of 100 to 300 bp in mungbean genotypes and were polymorphic. The above PCR-based and locus-specific markers could be employed for marker assisted breeding (MAB) programme as well as genotype conservation. These linked markers will boost the efficiency and precision of powdery mildew resistance breeding in mungbean.