Dynamic QTL analysis of protein content and glutamine synthetase activity in recombinant inbred wheat lines

Teng

et al. 2020

Preprint

Glutamine synthetase (GS) mediates the first step in the assimilation of inorganic nitrogen (N) into amino acids, however the function of GS encoding genes is not well understood in wheat (Triticum aestivum). We found that the cytosolic TaGS1.1 was the major transcripted GS1 gene and was up-regulated by low-N availability. CRISPR/Cas9 mediated genome editing was employed to develop two gs1.1 mutants with mutated TaGS1.1-6A, −6B, and -6D. Both mutants had lower grains per spike and grain yield per plant than the wild type under both low-N and high-N conditions in field experiments. In a hydroponic culture treated with different N resources, the two mutants was more sensitive to low-N stress than the wild type, but showed similar sensitivity to high ammonium stress with the wild type. The growth deficiency and impaired spike development were associated with the imbalance of N metabolites in the mutant plants. During grain filling, TaGS1.1 mutation reduced N translocation efficiency and delayed leaf N loss and grain N filling. Our results suggested that TaGS1.1 is important for N assimilation and remobilization, and required for wheat adaptation to N-limited conditions and spike development.HighlightThe wheat cytosolic glutamine synthetase TaGS1.1 is important for N assimilation and remobilization, and is required for wheat adaptation to low-N stress and spike development.

Section: Introductionmentioning

confidence: 99%

The wheat cytosolic glutamine synthetaseGS1.1modulates N assimilation and spike development by characterizing CRISPR-edited mutants

Teng

et al. 2020

Preprint

“…Two conditional QTLs related to protein content were detected at the grain filling stage. This is a good start for the study of the regulation of protein and starch content during wheat grain development by conditional QTLs ( Li et al., 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Genetic dissection of protein and starch during wheat grain development using QTL mapping and GWAS

et al. 2023

Protein, starch, and their components are important for wheat grain yield and end-products, which are affected by wheat grain development. Therefore, QTL mapping and a genome-wide association study (GWAS) of grain protein content (GPC), glutenin macropolymer content (GMP), amylopectin content (GApC), and amylose content (GAsC) were performed on wheat grain development at 7, 14, 21, and 28 days after anthesis (DAA) in two environments using a recombinant inbred line (RIL) population of 256 stable lines and a panel of 205 wheat accessions. A total of 29 unconditional QTLs, 13 conditional QTLs, 99 unconditional marker−trait associations (MTAs), and 14 conditional MTAs significantly associated (p < 10−4) with four quality traits were found to be distributed on 15 chromosomes, with the phenotypic variation explained (PVE) ranging from 5.35% to 39.86%. Among these genomic variations, three major QTLs [QGPC3B, QGPC2A, and QGPC(S3|S2)3B] and SNP clusters on the 3A and 6B chromosomes were detected for GPC, and the SNP TA005876-0602 was stably expressed during the three periods in the natural population. The QGMP3B locus was detected five times in three developmental stages in two environments with 5.89%–33.62% PVE, and SNP clusters for GMP content were found on the 3A and 3B chromosomes. For GApC, the QGApC3B.1 locus had the highest PVE of 25.69%, and SNP clusters were found on chromosomes 4A, 4B, 5B, 6B, and 7B. Four major QTLs of GAsC were detected at 21 and 28 DAA. Most interestingly, both QTL mapping and GWAS analysis indicated that four chromosomes (3B, 4A, 6B, and 7A) were mainly involved in the development of protein, GMP, amylopectin, and amylose synthesis. Of these, the wPt-5870–wPt-3620 marker interval on chromosome 3B seemed to be most important because it played an important role in the synthesis of GMP and amylopectin before 7 DAA, in the synthesis of protein and GMP from 14 to 21 DAA, and in the development of GApC and GAsC from 21 to 28 DAA. Using the annotation information of IWGSC Chinese Spring RefSeq v1.1 genome assembly, we predicted 28 and 69 candidate genes for major loci from QTL mapping and GWAS, respectively. Most of them have multiple effects on protein and starch synthesis during grain development. These results provide new insights and information for the potential regulatory network between grain protein and starch synthesis.

“…GSr 参与根部系氮素同化运转, GSe 参与籽粒发育过程中氮素利用 [4] 。GS 活性与小麦籽粒可溶性蛋白含量及产量密切相关 [5][6][7][8][9] 。水稻过表达 GS1 基因, 其 GS 活性及可溶性蛋白含量显著提高 [10] , 过表达 GS2 可以增强水稻的光呼吸和光合作用强度, 水稻过表达 GS2 和烟草过表达 GS2 均提高抗盐能力 [11][12] 。过表达 GSr 可提高水稻对盐、干旱及冷胁迫的敏感性 [13] 。 QTL 定位证明 GS 与小麦产量呈正相关 [6] 。可见, GS 与植物生长发育和抗逆密切相关。小麦是异源六倍体, 有 A、B、D 三个染色体组, 每组染色体都有一套 TaGS 同工酶基因, 比如 GS1 有 3 个基因编码, 即 GS1A、GS1B 和 GS1D。以前报道小麦 GSr 和 GSe 只有 2 个基因 [14] , 可能存在未发现的 GSr 和 GSe 同工酶基因。启动子位于基因的 5'端非编码区, 其结构和功能影响基因的转录调控。 Michael 等 [15] 发现拟南芥 GLN1:2…”

unclassified

Transcription characteristics of wheat glutamine synthetase isoforms and the sequence analysis of their promoters

Zhang

et al. 2020

Acta Agronom Sin

As a key enzyme for nitrogen assimilation in wheat, glutamine synthetase is grouped into two classes: cytosolic GS and chloroplastic GS (TaGS2), and cytosolic GS includes TaGS1, TaGSr, and TaGSe. In order to study the expression characteristics and regulatory mechanisms of GS isozymes in chromosome A, B, and D of heterohexaploid wheat, transcripts of TaGS isoforms were analyzed based on the third-generation sequencing technology transcriptome analysis, and 12 promoters of TaGS isozymes of Yumai 49 were cloned based on Chinese Spring genome, and the sequence of the promoters were analyzed. The results showed that TaGS1 was mainly transcribed on chromosome 6B, TaGSe and TaGSr on chromosome 4D, and TaGS2 on chromosome 2D. Furthermore, the distance from initiation codon ATG to initiation site of transcript for each promoter of TaGS was distinct. Promoter element analysis showed that the promoter of TaGS1 in 6B had more W-box, AC-I, ABRE, as-1, and methyl jasmonic response elements, the promoter of TaGSe in 4D had more stress response elements (MYB, MBS, LTR, etc.) and auxin response element, the promoter of TaGSr in 4D had more WRE3 and transcript factor response elements, the promoter of TaGS2 in 2D had more A-box, WRE3, ARE, and an AT enrichment region. In summary, the number, type and order of cis-elements of different promoters of TaGS isozymes were distinct, which provided the foundation for further study on the regulation mechanism of TaGS isozymes.