Cloning And Polymorphism Analysis Of SPL13 Gene In Wheat (Triticum Aestivum L.)

As one of the three most widely cultivated crops in the world,increasing wheat yield has been becoming the research focus of agricultural scientists all over the world.Triticum aestivum is allohexaploid that has evolved over a long period of time.The completion of its draft genome sequencing provided basis for cloning and functional analysis of genes related to important agronomic traits.SQUAMOSA promoter bingding protein-like(SPL)gene family is a family of transcription factors which play an important role in the growth and development of higher plants.However,there are few studies on SPL gene in wheat.Based on the genome sequence of common wheat Chinese Spring(CS),we analyzed the sequence,structure and evolutionary relationship of the SPLs in hexaploid wheat.The genes were cloned from ten wheat varieties with different grain sizes,and the polymorphism of TaSPL13 gene was analyzed.The main results are as follows:(1)The SBP domain sequence of rice SPLs was used as a template for BLAST searching.We found a total of 44 SPL genes in CS.Through phylogenetic analysis,we know that except for TaSPL3 and TaSPL12,all other SPL genes are very evolutionary conservative.There are 16 SPL genes in CS with miR156 target sites,these genes may be regulated by miR156,suggesting that these genes may play an important role in the growth and development of wheat.According to the results of gene structure analysis,we can see that there is little difference in the gene structure between the 44 genes screened in CS and the homologous genes in rice.(2)According to the analysis results of CS,we designed SPL13 primers that did not distinguish among the SPL13 of A,B and D chromosomes.Ten wheat varieties with different grain sizes were selected and randomly divided into 38 differentially expressed SPL13 genes.(3)All 38 SPL13 genes were found to have miR156 target sites,and the miR156 target sites were located in the exon of downstream SPL13 gene.Sequence alignment results of these genes showed that there is a big difference between the 5 SPL genes obtained from the small grains and the other 33 SPL.In addition,these 5 genes differed from other genes in SBP domain and phylogenetic relationship.Through statistical analysis of SPL13 gene mutation in Triticum aestivum,we found that the mutation frequency of SPL13 gene in medium and small grain wheat was much higher than that of large grain wheat and it was therefore speculated that the grain size of wheat was related to the mutation of SPL13.In conclusion,we conducted a relatively comprehensive analysis of the SPL gene family in CS and isolated the SPL13 gene from ten wheat varieties with different grain sizes.Our work showed that the SPL13 gene was different in the hexaploid wheat curtivars with different grain size,but the effects of these differences on the grain size of wheat will require further studying.