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Subject: Molecular Biology and Biotechnology × Author: Gupta, Meenu × End date: 2018 × Start date: 2010 ×
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    ThesisItemOpen Access
    Expression profiling of soluble starch synthase I gene during grain development for thermotolerance in wheat (Triticum aestivum L. em. Thell)
    (CCSHAU, 2014) Gupta, Meenu; Dhillon, Santosh
    The four genotypes of wheat i.e. two thermotolerant (WH 730 and WH 1021) and two thermosensitive (WH 147 and WH 711) were evaluated under two different sowing conditions (normal and late sown) to assess the effect of high temperature (HT) stress on grain yield traits and expression of soluble starch synthase I gene. Gene expression was studied by real time PCR analysis at 7 stages (2, 5, 8, 10, 15, 20 and 25 DAA) during grain development in developing grains and flag leaf. High temperature stress negatively affected all yield traits like number of tillers per plant, grain number per plant, thousand grain weight, biomass and grain yield per plant. Decreased grain filling duration under HT stress was not compensated by increased grain filling rate. The effect was more profound in case of thermosensitive genotypes. The order of thermotolerance based on heat susceptibility index (HSI) is: WH 730 (0.65) > WH1021 (0.79) > WH 711 (1.13) > WH 147 (1.52). In developing grains, temporal pattern of SSSI gene expression was altered and expression peaked earlier under LS conditions (15 DAA) than under NS conditions (at 20 DAA) in all genotypes studied. In flag leaf, peak expression under NS conditions was observed at 15 DAA in all genotypes while under LS conditions, expression peaked at 15 DAA in thermotolerant genotypes and at 10 DAA in thermosensitive genotypes. At late stages during grain development, SSSI gene expression fell more abruptly and to a higher level in case of thermosensitive genotypes in grains as well as flag leaf. Partial SSSI cDNA was sequenced from WH 730 (1916 bp), WH 1021 (1924 bp), WH 147 (1925 bp) and WH 711 (1924 bp) genotypes. Phylogram generated using different starch synthases isoforms clustered SSSI, SSSII, SSSIII and SSSIV into separate groups. WH 730 showed maximum tolerance to HT stress while WH 147 was least thermotolerant, based on the overall picture of physiological traits, yield traits and gene expression analysis studies.