Thumbnail Image

Thesis

Browse

222
 Reset filters

Settings

Start date: 22 × End date: 409 ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    ThesisItemOpen Access
    Morpho-Biochemical and Differential Gene Expression Studies of Phaseolus vulgaris-Colletotrichum lindemuthianuminteraction in Western Himalayas
    (SKUAST Kashmir, 0022) Safoora Shafi; Khan, M. Anwar
    Common bean (Phaseolus vulgaris L.) an annual legume crop, is considered as the most important grain legume species in the genus Phaseolus for direct human consumption. Anthracnose (ANT), caused by the hemi-biotrophic fungus Colletotrichum lindemuthianum(Sacc. & Magnus), limit the yield potential and has the greatest impact on the quality of seeds and pods of common beans. The present study was conducted on 219 common bean genotypes including local landraces, indigenous and exotic genotypes. Disease screening and morphological trait evaluation of the material under study was carried out at two locations (FoA, Wadura and MAR&ES, Izmarg, Gurez).Fifteen resistant genotypes were identified having stable performance under field and controlled conditions. Biochemical analysis of defense related enzymes against C.lindemuthianum(such as peroxidase, ascorbate peroxidase, lipid peroxidase and catalase) and C-based compounds (phenols, flavonoids and tannins) were examined using detached leaf method and comparative analysis from pods, stem, and seeds of resistant (WBE10) and susceptible genotype (SKAU127). All biochemical parameters examined were observed to be altering in the different tissues of the infected plants and at different course of time.Significant variation was observed for all the morphological traits includingdays to flower, days to pod initiation, days to harvest maturity, number of pods per plant, pod length, pod weight, pod thickness, number of seeds per pod and 100 seed weight with highest coefficient of variation reported in case of number of pods per plant (30.41%) followed by hundred seed weight (28.72%).Crossing was attempted between resistant and susceptible genotype and the differences between parents and populations for the anthracnose disease were substantial. The singlemarker analysis (SMA) was carried out on a set of resistant and susceptible genotypes by using candidate gene/ quantitative trait loci (QTLs) linked simple sequence repeat (SSR) markers for anthracnose and all the markers under study were validated on our germplasm (P-value < 0.05). Phenotypic variation explained (R2) by the markers was highest for CV542014 (10.17%). Furthermore, detailed meta-QTL (MQTL) analysis was carried out by combining the previously known 92 QTLs/ resistant gene loci for ANTresistance from 18 different studies involving 16 mapping populations. The meta-analysis results led to the identification of 11 MQTLs and 10 QTL hotspots. These MQTLs were validated by marker trait associations from previous genome-wide association studies and expression studies. The 11 MQTL regions contain 1251 candidate genes including several R genes and other defense related genes. Transcriptome analysis for resistant and susceptible genotype could identify 1823 differentially expressed genes (DEGs) between resistant and susceptible genotype at 120 hours post inoculation. Up-regulation of resistance genes containing LRR (PHAVU_001G134600g)and NAC domain containing protein (PHAVU_001G100500g)strongly favors resistance against C. lindemuthianum. Thus, the results of the study helped us to identify some novel sources of resistant genotypes as well as genes/ QTLs responsible for the resistance and susceptibility in common beans.
  • Thumbnail Image
    ThesisItemOpen Access
    Diversity of Xylocopa spp. (Hymenoptera:Apidae) in Northwest Himalayan Range of J&K and Ladakh
    (SKUAST Kashmir, 0022) Umer Bin Farook; Munazah Yaqoob
    Large carpenter bees (Xylocopa spp.) are generalist pollinators of wide geographical distribution. The genus Xylocopa Latreille (Xylocopinae: Xylocopini) comprises approximately 375 species of large, robust bees, superficially resembling bumble bees (Apinae: Bombini), that are distributed throughout the world. Two species viz., X. valga and X. violacea have been reported from the temperate zone of north western Himalayas but the key information regarding their nesting biology, morphometry and ecological studies in these regions is scanty. The taxonomic description and periodic revision of Xylocopa besides the molecular phylogenies are important for a region to know the available bee fauna viz a viz., addressing various biological issues such as relationship among species or genes, demographic changes and their migration patterns. The present investigation entitled “Diversity of Xylocopa spp. (Hymenoptera:Apidae) in Northwest Himalayan Range of J&K and Ladakh” was thus carried out on taxonomic review, molecular phylogeny, floral resources and nesting biology of different species of Xylocopa. During the investigation, a total of four Xylocopa species viz., X. fenestrata, X. valga, X. pubescens and X. dejeanii were recorded from UT of J&K and Ladakh. Taxonomic keys provided the clear cut easy recognition of both sexes of these bees. The morphological description emphasized on the size, colouration, punctuation, pubescens and distinct structural characters of these bees. Cytochrome Oxidase subunit 1 (CO1) (621 base pair length) from native Xylocopa fauna were amplified and sequenced for molecular phylogeny analyses. The tree topology clearly differentiated four sub-genera viz., Xylocopa, Koptortosoma, Ctenoxylocopa and Zonohirsuta. The Xylocopa spp. are polylectic in nature and feeds on various plants. A total of fifty-three species of flowering plants in 10 families viz., Asteraceae (11 spp.), Cucurbitaceae (3 spp.), Fabaceae (4 spp.), Lamiaceae (11 spp.), Rosaceae (10 spp.), Solanaceae (4 spp.), Oleraraceaea (1 sp.), Bignoniaceae (2 spp.), Rutaceae (3 spp.), Malvaceae (4 spp.). were found associated with four species of Xylocopa. To study the nesting behaviour of X. valga, wooden blocks, dried logs of apple/pear and bamboo sticks were installed manually. The devised artificial nesting structures except bamboo sticks provided nesting shelters for this pollinator. The study revealed maximum invasion of X. valga in wooden logs of Apple, Pear and Poplar. The nesting architecture revealed average nest length of 29.50±1.84 cm. The number of cells per nest ranged from 5-9 with a mean of 7.17±2.14 per nest. The average number of galleries recorded were 2.32 ± 1.14. An average of seven females and one male emerged from each nest. Taxonomic description provided the precise identification of this insect. High potential of artificial nesting structures providing nesting shelter to these bees can be useful in augmentation of these bees. Nesting biology of these bees is accredited to their conservation and management which would lead to increase in pollination services and decrease in costs of crop pollination in temperate, sub-tropical and cold arid conditions of UT of J&K and Ladakh.