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Summary: Drought is a deleterious abiotic stress factor that constrains crop growth and development. Post‐translational modification of proteins mediated by the ubiquitin–proteasome system is an effective strategy for directing plant responses to stress, but the regulatory mechanisms in wheat remain unclear. In this study, we showed that TaSDIR1‐4A is a positive modulator of the drought response. Overexpression of TaSDIR1‐4A increased the hypersensitivity of stomata, root length and endogenous abscisic acid (ABA) content under drought conditions. TaSDIR1‐4A encodes a C3H2C3‐type RING finger protein with E3 ligase activity. Amino acid mutation in its conserved domain led to loss of activity and altered the subcellular localization. The membrane‐bound transcription factor TaWRKY29 was identified by yeast two‐hybrid screening, and it was confirmed as interacting with TaSDIR1‐4A both in vivo and in vitro. TaSDIR1‐4A mediated the polyubiquitination and proteolysis of the C‐terminal amino acid of TaWRKY29, and its translocation from the plasma membrane to the nucleus. Activated TaWRKY29 bound to the TaABI5 promoter to stimulate its expression, thereby positively regulating the ABA signalling pathway and drought response. Our findings demonstrate the positive role of TaSDIR1‐4A in drought tolerance and provide new insights into the involvement of UPS in the wheat stress response. [ABSTRACT FROM AUTHOR]

Ethylene has an important role in regulating plant growth and development as well as responding to adversity stresses. The 1-aminocyclopropane-1-carboxylate synthase (ACS) is the rate-limiting enzyme for ethylene biosynthesis. However, the role of the ACS gene family in wheat has not been examined. In this study, we identified 12 ACS members in wheat. According to their position on the chromosome, we named them TaACS1-TaACS12, which were divided into four subfamilies, and members of the same subfamilies had similar gene structures and protein-conserved motifs. Evolutionary analysis showed that fragment replication was the main reason for the expansion of the TaACS gene family. The spatiotemporal expression specificity showed that most of the members had the highest expression in roots, and all ACS genes contained W box elements that were related to root development, which suggested that the ACS gene family might play an important role in root development. The results of the gene expression profile analysis under stress showed that ACS members could respond to a variety of stresses. Protein interaction prediction showed that there were four types of proteins that could interact with TaACS. We also obtained the targeting relationship between TaACS family members and miRNA. These results provided valuable information for determining the function of the wheat ACS gene, especially under stress. [ABSTRACT FROM AUTHOR]

Drought negatively affects plant growth and development to cause major yield losses in crops. Transcription factors (TFs) play important roles in abiotic stress response signaling in plant. However, the biological functions of membrane-bound transcription factors (MTFs) in abiotic stress have rarely been studied in wheat. In this study, we identified a homologue of the maize ZmNTL1 gene in wheat, which was designated as TaNTL1. TaNTL1 is a NAC family MTF (NTM1-like, NTL proteins) encoding 481 amino acid residues with a transmembrane motif at the C-terminal. Quantitative results and expression profile analysis showed that TaNTL1 could respond to drought. We demonstrated the transcriptional activity of TaNTL1 and that it could specifically bind to NAC recognition cis-acting elements (NACBS). The full-length TaNTL1 protein localized in the plasma membrane and TaNTL1 lacking the transmembrane motif (TaNTL1-ΔTM) localized in the nucleus. TaNTL1 was proteolytically activated by PEG6000 and abscisic acid (ABA). Phenotypic and physiological analyses showed that overexpression transgenic Arabidopsis exhibited enhanced drought resistance, which was greater with TaNTL1-ΔTM than TaNTL1. Transient silencing of TaNTL1 significantly reduced the resistance to drought stress in wheat. Germination by the TaNTL1 and TaNTL1-ΔTM transgenic Arabidopsis seeds was also hypersensitive to ABA. Most of the stress-related genes in transgenic plants were upregulated under drought conditions. These results suggest that MTF TaNTL1 is a positive regulator of drought and it may function by entering the nucleus through cleavage. • TaNTL1 identified as a NAC family membrane-bound transcription factor in wheat. • C-terminal transmembrane domain of TaNTL1 determines its subcellular localization. • TaNTL1 has a positive regulatory role under drought stress conditions. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum L.) is one of the most important crops in the world. Chlorophyll plays a vital role in plant development and crop improvement and further determines the crop productivity to a certain extent. The biosynthesis of chlorophyll remains a complex metabolic process, and fundamental biochemical discoveries have resulted from studies of plant mutants with altered leaf color. In this study, we identified a chlorophyll-deficiency mutant, referred to as chli , from the wheat cultivar Shaannong33 that exhibited an obvious pale-green leaf phenotype at the seedling stage, with significantly decreased accumulation of chlorophyll and its precursors, protoporphyrin IX and Mg-protoporphyrin IX. Interestingly, a higher protoporphyrin IX to Mg-protoporphyrin IX ratio was observed in chli. Lipid biosynthesis in chli leaves and seeds was also affected, with the mutant displaying significantly reduced total lipid content relative to Shaanong33. Genetic analysis indicated that the pale-green leaf phenotype was controlled by a single pair of recessive nuclear genes. Furthermore, sequence alignment revealed a single-nucleotide mutation (G664A) in the gene TraesCS7A01G480700.1, which encodes subunit I of the Mg-chelatase in plants. This single-nucleotide mutation resulted in an amino acid substitution (D221N) in the highly conserved domain of subunit I. As a result, mutant protein Tachli-7A lost the ability to interact with the normal protein TaCHLI-7A, as assessed by yeast two-hybrid assay. Meanwhile, Tachli-7A could not recover the chlorophyll deficiency phenotype of the Arabidopsis thaliana SALK_050029 mutant. Furthermore, we found that in Shaannong33, the protoporphyrin IX to Mg-protoporphyrin IX ratio was growth state-dependent and insensitive to environmental change. Overall, the mutation in Tachli-7A impaired the function of Mg-chelatase and blocked the conversion of protoporphyrin IX to Mg- protoporphyrin IX. Based on our results, the chli mutant represents a potentially useful resource for better understanding chlorophyll and lipid biosynthetic pathways in common wheat. [ABSTRACT FROM AUTHOR]

The small YABBY plant-specific transcription factor has a prominent role in regulating plant growth and developmental activities. However, little information is available about YABBY gene family in Triticum aestivum L. Herein, we identified 21 TaYABBY genes in the Wheat genome database. Then, we performed the conserved motif and domain analysis of TaYABBY proteins. The phylogeny of the TaYABBY was further sub-divided into 6 subfamilies (YABBY1/YABBY3, YABB2, YABBY5, CRC and INO) based on the structural similarities and functional diversities. The GO (Gene ontology) analysis of TaYABBY proteins showed that they are involved in numerous developmental processes and showed response against environmental stresses. The analysis of all identified genes in RNA-seq data showed that they are expressed in different tissues of wheat. Differential expression patterns were observed in not only control samples but also in stressed samples such as biotic stress (i.e., Fusarium graminearum (F.g), septoria tritici (STB), Stripe rust (Sr) and Powdery mildew (Pm), and abiotic stress (i.e., drought, heat, combined drought and heat and phosphorus deficiency), especially at different grain development stages. All identified TaYABBY-genes were localized in the nucleus which implies their participation in the regulatory mechanisms of various biological and cellular processes. In light of the above-mentioned outcomes, it has been deduced that TaYABBY-genes in the wheat genome play an important role in mediating various development, growth, and resistance mechanism, which could provide significant clues for future functional studies. [ABSTRACT FROM AUTHOR]

Early leaf senescence negatively impacts the grain yield in wheat (Triticum aestivum L.). Induced mutants provide an important resource for mapping and cloning of genes for early leaf senescence. In our previous study, Els2, a single incomplete dominance gene, that caused early leaf senescence phenotype in the wheat mutant LF2099, had been mapped on the long arm of chromosome 2B. The objective of this study was to develop molecular markers tightly linked to the Els2 gene and construct a high-resolution map surrounding the Els2 gene. Three tightly linked single-nucleotide polymorphism (SNP) markers were obtained from the Illumina Wheat 90K iSelect SNP genotyping array and converted to Kompetitive allele-specific polymerase chain reaction (KASP) markers. To saturate the Els2 region, the Axiom® Wheat 660K SNP array was used to screen bulked extreme phenotype DNA pools, and 9 KASP markers were developed. For fine mapping of the Els2 gene, these KASP markers and previously identified polymorphic markers were analyzed in a large F2 population of the LF2099 × Chinese Spring cross. The Els2 gene was located in a 0.24-cM genetic region flanked by the KASP markers AX-111643885 and AX-111128667, which corresponded to a physical interval of 1.61 Mb in the Chinese Spring chromosome 2BL containing 27 predicted genes with high confidence. The study laid a foundation for a map-based clone of the Els2 gene controlling the mutation phenotype and revealing the molecular regulatory mechanism of wheat leaf senescence. [ABSTRACT FROM AUTHOR]

Salt stress is an abiotic stress factor that limits high yields, and thus identifying salt tolerance genes is very important for improving the tolerance of salt in wheat. In this study we identified 274 TaRING-H2 family members and analyzed their gene positions, gene structures, conserved structural domains, promoter cis-acting elements and covariance relationships. And we investigated TaRING-H2-120 (TaSDIR1) in salt stress. Transgenic lines exhibited higher salt tolerance in the germination and seedling stages. Compared with the wild type, overexpression of TaSDIR1 upregulated the expression of genes encoding enzymes related to the control of reactive oxygen species (ROS), thereby reducing the accumulation of ROS, as well as increased the expression of ion transport-related genes to limit the inward flow of Na+ in vivo and maintain a higher K+/Na+ ratio. The expression levels of these genes were opposite in lines where TaSDIR1 was silenced by BSMV-VIGS, and the silenced wheat exhibited higher salt sensitivity. Arabidopsis mutants and heterologous TaSDIR1 overexpressing lines had similar salt stress tolerance phenotypes. We also demonstrated that TaSDIR1 interacted with TaSDIR1P2 in vivo and in vitro. A sequence of 80–100 amino acids in TaSDIR1P2 encoded a coiled coil domain that was important for the activity of E3 ubiquitin ligase, and it was also the core region for the interaction between TaSDIR1 and TaSDIR1P2. Overall, our results suggest that TaSDIR1 positively regulates salt stress tolerance in wheat. [ABSTRACT FROM AUTHOR]

The discovery and identification of gene families by using wide-genome and public databases is an effective way to gain initial insight into gene function, which also is one of the current hot spots of research. Chlorophyll ab-binding proteins (LHC) are important for photosynthesis and widely involved in plant adversity stress. However, the study in wheat has not been reported. In this study, we identified 127 TaLHC members from common wheat which were unevenly distributed on all chromosomes except 3B and 3D. All members divided into three subfamilies, LHC a, LHC b and the LHC t which was only discovered in wheat. All of them had maximum expression in leaves and contained multiple light-responsive cis-acting element, which were evidence of the extensive involvement of LHC families in photosynthesis. In addition, we also analyzed their collinear relationship, targeting relationship with miRNA and their responses under different stresses. Based on these analyses, it was found that TaLHC86 was an excellent candidate gene for stress resistance. The full-length ORF of TaLHC86 was 792 bp and was localized on the chloroplasts. The salt tolerance of wheat was reduced when BSMV-VIGS silenced TaLHC86 , and the photosynthetic rate and electron transport were also seriously affected. This study made a comprehensive analysis of the TaLHC family and found that TaLHC86 was a good gene for salt tolerance. [ABSTRACT FROM AUTHOR]

Protein and starch are the two most abundant components in wheat flour that co-influence dough processing quality. Studies have demonstrated that protein content and composition play a decisive role in wheat dough development. Additionally, starch has a significant effect on dough behaviour. The physicochemical and mixing properties of two wheat near-isogenic lines (NILs; NILZX1 and NILZX2) with different high-molecular-weight glutenin subunits (HMW-GS) were analyzed to shed light on the role of starch and protein in the dough mixing process. The NILZX1 dough with superior HMW-GS combination had higher protein content than NILZX2 dough. Whereas NILZX1 had a lower storage modulus and shorter dough stability time than NILZX2. During the mixing process, the torque of NILZX1 dough was lower than that of NILZX2; the microstructure of NILZX1 dough was greatly destroyed in the starch-dominant phase, leading to inferior dough quality. NILZX2 with higher B-type starch content, relative crystallinity, and viscosity showed greater dough quality. Taken together, physicochemically, starch had a more substantial effect on the dough mixing properties than protein in the two NILs. The findings provide a foundation for exploring the contribution of starch to dough properties. • Two wheat lines with similar protein components were evaluated in their quality. • Superior HMW-GSs did not have great contribution on dough properties as expected. • Micro-structures of gluten at four dough mixing stages were observed and compared. • Higher B-type starch content stabilized dough structure throughout mixing process. • Starch may make dominant contribution to rheological properties of wheat dough. [ABSTRACT FROM AUTHOR]