Cloning And Expression Analysis Of Wheat Stay-green Gene TαSGR

Leaf senescence in plants is an internally programmed degeneration process leading to death.The most obvious feature in leaf senescence is the degradation of chlorophyll and the decrease of photosynthetic capacity.The degradation of chlorophyll would lead to the decline of quality and yield.Delaying the degradation of chlorophyll can prolong the grain filling period,so as to improve the yield.Studies have shown that the stay-green gene plays an important role in chlorophyll degradation of the diploid model crop Arabidopsis thaliana and rice.However,there is no report on the function of SGR in polyploid wheat.In this study,the cDNA and gDNA of wheat Stay-green gene TαSGRs were cloned.The cDNA sequences were translated into amino acid sequences for bioinformatics analysis.The expression pattern of TαSGR-5B was analyzed and the plant expression vector was constructed through the TαSGR-5B sequence.Genomic DNA was sequenced and functional markers were developed.It laid a foundation for functional verification of TαSGR gene and application of functional markers in assisted breeding.The main findings are as follows:1.The candidate sequences of wheat TαSGR on 5 A,5B and 5D genomes were obtained by comparing the sequences of HvSGR in wheat genome library URGI.According to the differences among the three genome candidate sequences,genome specific primers were designed.Three alleles of TαSGR,TαSGR-5A,TαSGR-5B and TαSGR-5D were cloned and located on the fifth chromosome arm of wheat.The structure of the gene was conservative,and the similarity of amino acids was as high as 95.48%,which might contain conserved domains.2.The expression of TαSGR-5B gene is induced by darkness,exogenous ABA,exogenous 6-BA and natural aging,and down-regulated under the induction of exogenous 6-BA.At the same time,two plant expression vectors were constructed according to the coding region of TαSGR-5B gene for transformation and subcellular localization,respectively.3.The three alleles of TαSGR contain three exons and two introns.The length of genome sequence corresponding to TαSGR-5A coding region is 1478 bp and the coding region is 834 bp.Two SNP loci(G/C and G/A)were detected.The length of genome sequence corresponding to TαSGR-5B coding region is 1475 bp and the coding region is 822 bp.Two SNP loci(C/T and G/T)were detected.The length of genome sequence corresponding to TαSGR-5D coding region is 1477 bp and the coding region is 843 bp.No SNP loci were detected.The sequence is conservative.4.The corresponding molecular markers TαSGR-5A-dCAPS and TαSGR-5B-CAPS were developed according to the polymorphism of TαSGR-5A and TαSGR-5B gene sequences.