NATH, AMARJIT K.SHARMA, ANKITA2020-01-022020-01-022019-12http://krishikosh.egranth.ac.in/handle/1/5810139230ABSTRACT Heat stress leads to adverse effect on Potato cultivation affecting the tuberization and the bulking process. Being a signaling molecule, it is hypothesized that annexins might play important role in tuberization under heat stress condition. Ten annexins from potato and 13 annexins from tomato were identified using bioinformatics tool. Annexin gene proteins from potato and tomato were found to have an average molecular weight of 36kDa. Both potato and tomato annexins showed differential location of the annexin genes on 12 chromosomes. Expression profiling of Potato annexin genes under heat stress conditions revealed strong up-regulation of annexins in heat tolerant potato cultivar Kufri Surya as compared to susceptible one i.e Kufri Chandramukhi indicating their role as key signaling molecule under heat stress conditions. The annexin gene StAnn1 showed a uniform pattern of elevated gene expression in both leaves and stolon under heat stress throughout the developmental stage of potato cultivar KS as compared to potato cultivar KCM. Significant increase in peroxidase, anthocyanin and proline content was observed in heat tolerant cultivar Kufri Surya on different intervals of exposure to heat stress. The content of MDA was significantly less in Kufri Surya as compared to Kufri Chandramukhi indicating much less membrane damage in the tolerant potato cultivar KS. The annexin gene StAnn1 was isolated and cloned from Kufri Surya and over expressed in heat susceptible cultivar Kufri Chandramukhi for exploiting its potential for providing heat stress tolerance in other susceptible potato cultivars. Agrobacterium mediated genetic transformation protocol was standardized for potato cultivar Kufri Chandramukhi where selective MS medium with composition containing IAA 0.042mg/L, GA33.0 mg/L, Zeatin 3.0 mg/L, NAA 0.008 mg/L, Kan 50 mg/L, Carb 250 mg/L, Cefo 100 mg/L showed maximum percentage of callus formation i.e 76 % and shoot regeneration. The best rooting was observed on selective root regeneration MS medium containing 50mg/L Kan and 0.3mg/L IAA. On exposure to in vitro salt stress, transgenic KCM plants expressing StAnn1 annexin gene, phenotypically showed better tolerance as compared to the control plants depicting its potential in providing tolerance to other abiotic stress also. A decline in number of roots, nodes/plant and plant height was observed in control shoots as compared to putative transgenic shoots.ennullThesis