Browsing by Author "NARESH KUMAR SAMAL"
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ThesisItem Open Access Molecular and biochemical basis of differential aphid infestation in wild species of Brassica(DIVISION OF MOLECULAR BIOLOGY AND BIOTECHNOLOGY ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI, 2019) NARESH KUMAR SAMAL; Ramcharan BhattacharyaRapeseed-mustard accounts for approximately 13% of the total global oilseed production. The global productivity of rapeseed-mustard is estimated to be 2244kg/ha. In the National scenario the productivity of rapeseed-mustard is 1183kg/ha, which is much lower than the global average. Indian mustard (Brassica juncea) is the chief oil yielding crop in this group. The productivity of mustard is severely affected by various biotic and abiotic stresses among which most notable is the biotic stress imposed by aphids. Aphids are light yellow to dark grey in colour, they feed by extracting the sugary sap from the phloem through their hardened stylet. Aphids poses a very high potential of yield reduction ranging from 9 to 91%. The available control measures such as physical, chemical and biological control measures are seemed to be very ineffective. Though the chemical control measures are the most predominantly used control measure but its detrimental effects towards environment and animal health has urged the scientific community to look for more eco-friendly and sustainable approaches for aphid control. In this respect the natural resistance present among the host plants as genetic resistance forms the best alternative. But unfortunately, due to non-availability of crossable germplasms no resistant cultivar is so far produced for cultivable germplasms. In the present study screening for aphid resistance in 22 wild relatives of Brassica was carried out, out of which 4 found to be resistant and 2 are moderately resistant to aphid infestation. Further Biochemical and gene-expression analysis of defence related genes and enzymes in selected wild germplasms showing resistance to mustard aphids was carried out. The biochemical study revealed more activation of redox signalling related genes and other defence genes in resistant species compared to their activation in susceptible species following aphid infestation as a greater number of enzymes showed higher activity in resistant species compared to moderate and susceptible types. Also, transcriptome data was generated for one of the resistant species Eruca sativa. The generated genomics data will be useful in developing markers to assist in gene introgression process. The data of this research led to the foundation of gene introgression from wild relatives of Brassica for aphid resistance which can be utilised in distant hybridisation programs for development of resistant cultivars in Brassica cultivated species. Keywords :-