Analysis Of High GPC Genes Derived From Wild Emmer

The grain protein content(GPC)is an important trait for both nutritional value and end-use quality of wheat.However,the protein levels in modern wheat grains are inherently low because of the negative correlation between GPC and grain yield and the long-term wheat breeding practice that focused on high grain yield.due to the grain protein content and yield of negative correlations,long-term focus on high-yield breeding,modern breeding common varieties of grain protein content is low.Wild emmer wheat(Triticum turgidum ssp.dicoccoides,2n=4x=28,AABB)gene pool harbors wide genotypic variations in GPC.The dissection of candidate genes that associated with high GPC is a challenge due to the complex characteristic of this trait.Here,the developing grains of wide hybrids and their parents wild emmer D1,D97 and common wheat Chuannong 16(CN16)were employed for comparative transcriptome analysis to decipher the candidates related to GPC.The main results are as following:1.The comparison of RNA-seq profiles between BAd107-4 and its bi-parents D1 and CN16 revealed 23 differentially expressed genes(DEGs)that may be involved in wheat grain protein accumulation.Of 23 candidates,21,11,19 GPC candidate genes were detected in D1,CN16 and BAd107-4,respectively,implying wild emmer genes were successfully introgressed into common wheat.2.Using wild emmer genome annotation files,we identified 26 DEGs related to grain storage proteins in a comparision between D1 and BAd107-4 as well as CN16.We found66.67% gliadinin and 78.57% glutenin coding genes were significantly up-regulated in D1 and hybrid Bad107-4.These results suggest that these genes may contribute to the high GPC in D1 and BAd107-4.3.We identified the high expression level of NRT1 in BAd107-4 and D1;the NRT-PII was specificly expressed in BAd107-4 and D1.Therefore,we propose that the higher expression of NRT1 gene in D1 and BAd107-4 may increase the nitrate uptake and transport,while the specifically expressed NRP-II may enhance the nitrogen utilization that finally promote the grain protein accumulation through affecting synthesis of amino acid in wheat.4.The comparison of RNA-seq profiles between BAd7-209 with high GPC,BAd23-1 with low GPC and its bi-parents D97 and CN16 revealed 21 differentially expressedgenes(DEGs)that may be involved in wheat grain protein accumulation.Compared with CN16,there were 19,17 DEGs were up-regulated in D97 and BAd 7-209.5.We identified 29 DEGs related to glutenin and gliadinin D97 and BAd7-209 compared to CN16,suggesting that these genes may also contribute to the high GPC in D97 and BAd7-209.Among them,TRIDC2BG036820 was up-regulated in both D97 and BAd7-209.This gene related to the formation of the protein molecular disulfide bond that may affected grain gluten aggregation and avenin-like protein and gliadin protein synthesis.6.The comparison of RNA-seq profiles between BAd7-209,BAd23-1 and its biparents D97 and CN16,we found 6 out of 8 DEGs related to protein processing in the endoplasmic reticulum were up-regulated in D97,BAd7-209 compared to CN16,BAd23-1.Thus,we propose that mechanism of high GPC in wild emmer D97 may relate to the regulating process of proteins in the endoplasmic reticulum.