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Subject: Agricultural Biochemistry × Start date: 2010 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Identification of loci governing nodulation efficiency and drought tolerance traits using GWAS approach and validation by QTL mapping in horsegram (Macrotyloma uniflorum)
    (Palampur, 2021-11-26) Choudhary, Sunny; Chahota, R.K.
    Macrotyloma uniflorum is a popular self-pollinated diploid (2n=2x=20) legume. Because of its drought resilience, resistance to heavy metal stress, antioxidant content, antimicrobial activities, and many medicinal qualities, horsegram is a crop of interest and a possible future food source. Drought tolerance and nodulation efficiency characteristics were assessed using a core set of 96 horsegram genotypes. The trial was held in a polyhouse in Palampur (Himachal Pradesh). Plants were sown in polytubes under two environments. At the relevant development stages, phenotypic data was collected. Following the separation of DNA from plants, samples were genotyped. SSR and SNP markers were used to genotype the samples. Six QTLs were associated with the number of nodules, seven with root length, and the most QTLs (12) were identified for root moisture content in the analysis of SSR markers. For root volume, eight QTLs were found, whereas for shoot fresh weight, three QTLs were discovered. Nine QTLs for days to temporary wilting, seven for RWC, and five for root fresh weight were identified. Five QTLs were shown to be linked to days to temporary wilting. Nine QTLs were discovered for the number of nodules. Six QTLs were discovered to be linked to root fresh weight. Root length had the highest number of QTLs (21), indicating the complexity of this important characteristic. Fourteen QTLs were discovered for root volume. There were 10 and 13 QTLs identified for relative water content and shoot fresh weight, respectively. These possible indicators will help us explore the drought resistance and nodulation efficiency mechanisms of horsegram in the near future. The use of these markers to perform positional cloning of genes in horsegram plants will provide new insights into drought tolerance and nodulation efficiency, allowing breeders to conduct experiments to further improve varieties for better adaptation to harsh and dry environmental conditions, which negatively affect plant growth and development and ultimately result in yield losses.
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    ThesisItemOpen Access
    PHYTOCHEMICAL STUDIES OF VIRUS INFECTED CAPSICUM AND MOLECULAR CHARACTERISATION OF VIRAL PATHOGEN
    (CSKHPKV. Palampur, 2020-01-31) SINGH, SHIPRA; Sharma, Neelam
    Capsicum is a cash crop of Himachal Pradesh commonly known for the abundance of antioxidants. Viral disease incidence has become very prominent in this crop. A total 19 viruses are known to infect Capsicum crop in India. In the present investigation entitled, “Phytochemical studies of virus infected Capsicum and molecular characterisation of viral pathogen”, a survey was conducted and 51 leaf samples were collected on the basis of symptoms from three districts of Himachal Pradesh i.e. Kangra, Kullu and Mandi. All the collected samples were analysed for the presence of viruses and their effect on phytochemical constituents. In addition to this, molecular characterisation of most prevalent virus was carried out. Screening of the samples for the presence of viruses through DAS-ELISA and identification and confirmation through RT-PCR revealed that CMV, PVY, PVX, GBNV, PSTVd (viroid) and TYLCV were the common viruses which infect Capsicum crop in Himachal Pradesh. The percent viral infection in Capsicum was 58.8 percent for CMV, 37.2 percent for PVY, 7.8 percent for TYLCV, 29.4 percent for PVX and 1.96 percent for PSTVd and GBNV both. Thus, CMV was the most prevalent virus in Capsicum crop. A significant decrease was observed in virus infected leaf samples of Capsicum for antioxidant activity, total carotenoids, total chlorophyll and ascorbic acid content Whereas total phenols and total flavonoids increased in infected samples.The molecular characterisation of CMV was carried out. An amplicon of approximately 829 bp, 958 bp, 1,314 bp, 373 bp, 842 bp and 647 bp for 1a helicase,1a methyltransferase, 2a, 2b, 3a and 3b genes were obtained. BLASTn analysis revealed that 1a helicase protein gene showed 98.35 percent identity with 1a helicase isolate of Capsicum sp. from Germany,1a methyltransferase protein gene showed 98.21 percent identity with 1a methyltransferase protein gene isolate of Tagetus erecta. from India, 2a protein gene showed 99.39 percent identity with Cucumber mosaic virus isolate TC segment of RNA -2 from UK, 2b protein gene showed 94.07 percent identity with 2b protein genes from Germany, movement protein (3a) gene showed 99.28 percent identity with Cucumber mosaic virus isolate CMV12 3a protein (3a) gene of Zucchini from Poland and Coat protein (3b) gene showed 99.23 percent identity with CP gene for coat protein of Valeriana from India.Comparative genome sequence analysis and phylogenetic analysis of CMV genes based on subgroups revealed that CMV-PLP 8 isolate belongs to subgroup-II of CMV.