Allele mining for heat stress related starch synthase gene in cultivated and wild species of wheat

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Date
2017
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Punjab Agricultural University, Ludhiana
Abstract
The present study was carried out to identify allelic variants in soluble starch synthase I (SSI) gene in 20 wheat genotypes including nine wild wheats, one durum wheat and ten hexaploid wheats. Candidate SSI gene located on wheat chromosome 7 (7A, 7B, 7D) was selected. After primer designing, SSI gene was amplified, cloned and sequenced in these 20 wheat genotypes though sequences of three wheat genotypes could not be obtained. After manual curation of raw data of these sequences, contigs were assembled and 9 exons and 8 introns were predicted like the reference SSI gene. There were 286 intronic SNPs and 45 exonic SNPs contributing to 221 transitions and 110 transversions. First exon has 18 SNPs while 3-6 SNPs were detected in rest of the exons. No exonic SNP was detected in wild genotype Triticum dicoccoides acc. pau14801 and four cultivated genotypes Giza, Arbon, C306 and PBW343. Out of 45 exonic SNPs, 12 contributed towards non-synonymous amino acid substitutions and none of these substitutions lies in active sites of SSI protein. Also important catalytic domain of SSI gene glycosyltransferase 5 (GT-5) lies outside predicted eight active sites of protein. GT-5 domain lies from exons 1- 6 and six SNPs corresponding to non-synonymous substitutions falls in this region. These six SNP based alleles from four wild progenitor species of Aegilops tauschii acc. pau14102, Aegilops tauschii acc. pau3747, Aegilops speltoides acc. pau15081 and Triticum dicoccoides acc. pau7107 and two cultivated genotypes Impala and C591 could be candidate SNPs for improved heat stress tolerance.
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