Wheat Gene Research Articles

Pyramiding of transgenic immune receptors from primary and tertiary wheat gene pools improves powdery mildew resistance in the field.

Introgression of resistance genes from wild or related species is a common strategy to improve disease resistance of wheat cultivars. Pm17 is a gene that confers powdery mildew resistance in wheat. It encodes an NLR type of immune receptor and was introgressed from rye to wheat as part of the 1RS chromosome arm translocation several decades ago. So far it has not been possible to separate Pm17 from its co-introgressed rye genes due to suppressed recombination. Here we tested in the field transgenic Bobwhite wheat overexpressing Pm17 without any other rye genes. Four transgenic events showed high levels of PM17 protein accumulation, strong powdery mildew resistance, and no pleiotropic effects during three field seasons. We used a combined approach of transgene insertion and cross-breeding to generate lines co-expressing Pm17 and Pm3, or Pm17 and Pm8. Blumeria graminis f. sp. tritici infection tests confirmed additive, race-specific resistance of the two pyramided transgenes in lines Pm17+Pm3b and Pm17+Pm8. Furthermore, pyramided lines showed strong powdery mildew resistance during three field seasons. We conclude that the combination of overexpressed NLR genes from the extended gene pool broadens and diversifies wheat disease resistance.

An integrated strategy involving high-throughput sequencing to characterize an unknown GM wheat event in Canada.

Glyphosate-resistant wheat plants were discovered in southern Alberta in 2017, representing an unauthorized GM release in Canada. The Canadian Food Inspection Agency undertook a series of experiments to characterize and identify this unknown GM wheat, as well as to develop and validate construct-specific and event-specific qPCR assays. Results of PCR-based assays and Sanger sequencing indicated the presence of CaMV 35S promoter (p35S), Rice Actin 1 intron (RactInt1), CP4-EPSPS gene and nopaline synthase terminator (tNOS) elements in the unknown GM wheat. Genome walking and bead capture strategies, combined with high-throughput sequencing, were used to identify the 5' and 3' wheat junctions and the subsequent mapping of the insert to chromosome 3B of the wheat genome. A probable transformation vector, pMON25497, was recognized, and further testing identified the unknown GM wheat as MON71200 event, one of two events obtained with the pMON25497 vector. The two construct-specific assays targeted the junctions of the RactInt1 and the CP4-EPSPS elements and the CP4-EPSPS and tNOS elements, while the event-specific assay was located at the 3' junction into the wheat genome. Both construct-specific and event-specific assays had limits of detection of 0.10% of MON71200 in a seed pool. As expected, the two construct-specific assays cross-reacted with other wheat and corn events containing the same elements in the same order. No cross-reactivity was observed for the event-specific assay. The integrated strategy employed in this study can serve as a model for other cases when facing similar challenges involving unknown GM events.

Genome-Wide Identification and Characterization of Glutaredoxin Family Genes in Common Wheat

Glutaredoxins (GRXs) are small-molecular-weight proteins present in a wide range of organisms, and they play a key role in maintaining the redox homeostasis of cells. Most studies on GRXs are conducted in animals and humans, and those conducted on plants are scarce. The number and types of GRX genes vary in different plants. According to the active sites, the GRX family can be further divided into the CPYC, CGFS, and CC subfamilies. The CPYC and CGFS subfamilies are present in eukaryotes. The CC subfamily is exclusively present in higher plants and has the highest number of genes. In this study, 85 GRX genes were identified in common wheat (Triticum aestivum L.) using a bioinformatic method, wherein 12, 9, and 64 belonged to the CPYC, CGFS, and CC subfamilies, respectively. All TaGRX genes were homogeneously distributed in the three subgenomes of wheat. The gene structure analysis revealed that TaGRX members had 1–7 introns. The conserved motif analysis revealed that members of the same TaGRX subfamily had similar motifs. An analysis of cis-regulatory elements of promoters demonstrated that most TaGRX members had auxin-responsive elements; cis-regulatory elements, such as methyl jasmonate (MeJA), MYB, and abscisic acid (ABA), were distributed in all subfamilies, and the cell-cycle regulation element was only observed in the CC and CPYC subfamily members. Additionally, the synteny of the GRX genes in wheat, in wheat and Arabidopsis, and in wheat and barley was analyzed to clarify the evolutionary correlation of TaGRXs. The expression characteristics of TaGRXs were investigated, and TaGRX expression in various tissues and its responses to different abiotic stresses were preliminarily determined. This study provides a reference for the functional analysis of TaGRXs and understanding their role in molecular breeding of wheat.

Genome-wide identification and expression analysis of the NHX gene family under salt stress in wheat (Triticum aestivum L).

Salt stress affects plant growth and development, resulting in the loss of crop yield across the world, and sodium-proton antiporters (NHXs) are one of the genes known to promote salt tolerance in transgenic plants. In this study, we conducted a comprehensive genome-wide analysis and expression profile of NHX genes in wheat under salinity stress. We identified 30 TaNHX genes in wheat based on the Na+/H+ exchanger domain, with all genes containing an amiloride motif except one, a known for inhibiting Na+ ions in plants. Phylogenetic analysis classified these genes into three classes with subfamilies: 12 were localized in vacuoles, while 18 were in the endoplasmic reticulum and plasma membrane. Promoter analysis revealed stress-related cis-acting elements, indicating their potential role in abiotic stress tolerance. The non-synonymous (Ka)/synonymous (Ks) ratios highlighted that the majority of TaNHX genes experienced robust purifying selection throughout their evolutionary history. Transcriptomis data analysis and qRT-PCR demonstrated distinct expression patterns for TaNHX genes across various tissues when subjected to salt stress. Additionally, we predicted 20 different miRNA candidates targeting the identified TaNHX genes. Protein-protein interaction prediction revealed NHX6's involvement in the SOS1 pathway, while NHX1 gene exhibit proton antiporter activity. Molecular dynamics (MD) simulations were also conducted to examine the interactions of TaNHX1, TaNHX2, and TaNHX3. These results represent a significant advancement in our understanding of the molecular mechanisms governing Na+ transporters. This may also offer promising avenues for future studies aimed at unraveling the intricate details of their biological roles and applications.

Phosphate deficiency responsive TaSPX3 is involved in the regulation of shoot phosphorus in Arabidopsis plants

SPX (SYG/PHO81/XPR1) domain genes have been reported to play vital roles in the Phosphorus (Pi) signaling network in Arabidopsis thaliana and rice. However, the functions of SPX proteins in wheat remain largely unknown. In this study, the full-length cDNA sequence of the TaSPX3 gene was cloned from the common wheat variety Zhengmai9023. The expression of TaSPX3 was up-regulated in eight different genotypes of wheat under low phosphorus (LP) stress, indicating that TaSPX3 responds to Pi limitation in multiple wheat genotypes. The transcription level of TaSPX3 was also detected in the absence of seven different elements, showing certain specificity for Pi deficiency in wheat. Over expressing TaSPX3 in Arabidopsis can alleviate Pi deficiency symptoms at the seedling stage and promote the growth of plant, and advance the flowering period at the adult stage. The expression of 7 genes associated with the Pi starvation signal pathways was analyzed using qRT-PCR. The results showed that TaSPX3, along with AtSPX1, AtRNS1, AtIPS1, AtPAP2, AtPAP17 and AtAT4, were all induced by Pi deficiency. This study reveals that the TaSPX3 gene in wheat is involved in the response to phosphorus stress and may affect shoot phosphorus levels through AT4 or PAPs-related pathways. Overall, our study provides new insights into the regulation of plant response under LP conditions and the molecular mechanism underlying the role of the wheat SPX gene in coping with LP stress.

Molecular mapping of two novel cold resistance genes in common wheat by 660K SNP array.

The online version contains supplementary material available at 10.1007/s11032-023-01425-w.

Molecular characterization of genes involved in tolerance of cadmium in Triticum aestivum (L.) under Cd stress

The NRAMPs (natural resistance-associated macrophage proteins) are major transporters for the absorption and transport of metals like Pb, Zn, Mn, Fe, and Cd in plants. While NRAMP gene family members have been extensively studied as metal transporters in model and other plants, little information has been reported on their role in Triticum aestivum, particularly in response to Cd stress. Current study reported 13 NRAMP candidates in the genome of T. aestivum. Phylogenetic analysis divided these into three clades. Motif and gene structure study showed that members in the same clades shared the same location and pattern, which further supported the phylogenetic analysis. The analysis of cis-acting elements in promoter sequences of NRAMP genes in wheat identified stress-responsive transcription factor binding sites. Multiple sequence alignment identified the conservation of important residues. Based on RNA-seq and qRT-PCR analysis, Cd stress-responsive variations of TaNRAMP gene expression were reported. This study provides comprehensive data to understand the TaNRAMP gene family, its features, and its expression, which will be a helpful framework for functional research.

The Cell Wall-Related Gene Families of Wheat (Triticum aestivum)

Wheat crops provide 20% of calories worldwide. Cell walls function in plant growth, are part of biotic and abiotic stress resistance, and provide plant mechanical strength and adaptability. These functions factor into the productivity of wheat. The genes that produce and maintain the plant cell wall are up to 10% of the genome in many varied families. Previously, curated cell wall gene families have been published for maize and rice, two other important crop grasses. Here, 81 cell wall-related wheat gene families curated via sequence similarity to maize and rice and unique family protein motif searches are presented. A total of 4086 wheat, 1118 maize, 1036 rice, and 955 Arabidopsis genes were aligned and placed into gene family trees to present homologs for all four species. Due to hexaploidy, many wheat cell wall gene families show expected triplication of genes per family over maize, rice, and Arabidopsis. However, several families contained more wheat genes than expected. The utility of this research is demonstrated with an example from a pre-harvest sprouting study to identify specific gene families rather than the less descriptive identification available with standard bioinformatic searches.

Characterization and expression analysis of nitrate reductase 6-1ABD gene in hexaploid bread wheat under different nitrogen regimes

Characterization and expression analysis of nitrate reductase 6-1ABD gene in hexaploid bread wheat under different nitrogen regimes

Transcriptional and protein structural characterization of homogentisate phytyltransferase genes in barley, wheat, and oat

BackgroundHomogentisate phytyltransferase (HPT) is the critical enzyme for the biosynthesis of tocopherols (vitamin E), which are the major lipid-soluble antioxidants and help plants adapt to various stress conditions. HPT is generally strictly conserved in various plant genomes; however, a divergent lineage HPT2 was identified recently in some Triticeae species. The molecular function and transcriptional profiles of HPT2 remain to be characterized.ResultsIn this study, we performed comprehensive transcriptome data mining of HPT1 and HPT2 in different tissues and stages of barley (Hordeum vulgare), wheat (Triticum aestivum), and oat (Avena sativa), followed by qRT-PCR experiments on HPT1 and HPT2 in different tissues of barley and wheat. We found that the common HPT1 genes (HvHPT1, TaHPT1s, and AsHPT1s) displayed a conserved transcriptional pattern in the three target species and were universally transcribed in various tissues, with a notable preference in leaf. In contrast, HPT2 genes (HvHPT2, TaHPT2, and AsHPT2) were specifically transcribed in spike (developmentally up-regulated) and shoot apex tissues, displaying a divergent tissue-specific pattern. Cis-regulatory elements prediction in the promoter region identified common factors related to light-, plant hormone-, low temperature-, drought- and defense- responses in both HPT1s and HPT2s. We observed the transcriptional up-regulation of HvHPT1 and HvHPT2 under various stress conditions, supporting their conserved function in environmental adaption. We detected a clear, relaxed selection pressure in the HPT2 lineage, consistent with the predicted evolution pattern following gene duplication. Protein structural modelling and substrate docking analyses identified putative catalytic amino acid residues for HvHPT1 and HvHPT2, which are strictly conserved and consistent with their function in vitamin E biosynthesis.ConclusionsWe confirmed the presence of two lineages of HPT in Triticeae and Aveninae, including hexaploid oat, and characterized their transcriptional profiles based on transcriptome and qRT-PCR data. HPT1s were ubiquitously transcribed in various tissues, whilst HPT2s were highly expressed in specific stages and tissue. The active transcription of HPT2s, together with its conserved cis-elements and protein structural features, support HPT2s’ role in tocopherol production in Triticeae. This study is the first protein structural analysis on the membrane-bound plant HPTs and provides valuable insights into its catalytic mechanism.

Mapping of QTLs and meta-QTLs for Heterodera avenae Woll. resistance in common wheat (Triticum aestivum L.)

BackgroundIn hexaploid wheat, quantitative trait loci (QTL) and meta-QTL (MQTL) analyses were conducted to identify genomic regions controlling resistance to cereal cyst nematode (CCN), Heterodera avenae. A mapping population comprising 149 RILs derived from the cross HUW 468 × C 306 was used for composite interval mapping (CIM) and inclusive composite interval mapping (ICIM).ResultsEight main effect QTLs on three chromosomes (1B, 2A and 3A) were identified using two repeat experiments. One of these QTLs was co-localized with a previously reported wheat gene Cre5 for resistance to CCN. Seven important digenic epistatic interactions (PVE = 5% or more) were also identified, each involving one main effect QTL and another novel E-QTL. Using QTLs earlier reported in literature, two meta-QTLs were also identified, which were also used for identification of 57 candidate genes (CGs). Out of these, 29 CGs have high expression in roots and encoded the following proteins having a role in resistance to plant parasitic nematodes (PPNs): (i) NB-ARC,P-loop containing NTP hydrolase, (ii) Protein Kinase, (iii) serine-threonine/tyrosine-PK, (iv) protein with leucine-rich repeat, (v) virus X resistance protein-like, (vi) zinc finger protein, (vii) RING/FYVE/PHD-type, (viii) glycosyl transferase, family 8 (GT8), (ix) rubisco protein with small subunit domain, (x) protein with SANT/Myb domain and (xi) a protein with a homeobox.ConclusionIdentification and selection of resistance loci with additive and epistatic effect along with two MQTL and associated CGs, identified in the present study may prove useful for understanding the molecular basis of resistance against H. avenae in wheat and for marker-assisted selection (MAS) for breeding CCN resistant wheat cultivars.

PRESENT STATUS AND FUTURE PERSPECTIVES OF WHEAT (TRITICUM AESTIVUM L.) RESEARCH IN UZBEKISTAN

Wheat (Triticum spp.) is one of the premier staple foods consumed by one-third of the world’s population. Bread wheat (Triticum aestivum L.) is the only allohexaploid species with a genome formula BBAADD. Until now, from a selection point of view, a decline showed in the genetic potential of this type of wheat. However, the solution to this problem can be by developing high-yielding, disease- and pest-resistant cultivars using wheat-related species, ancient local landraces, and germplasm resources. Therefore, extensive study of the wheat gene pool using molecular tools, including identifying primary sources, is highly beneficial. For wheat improvement, breeding opportunities offer significant enhancements via genetic mapping approaches. The review focuses on the common wheat germplasm, wheat genetic approaches for genetic mapping, identification, and RWA (Russian wheat aphid) resistance, nested association mapping (NAM) population, DNA barcoding of Uzbekistan elite bread wheat cultivars, DNA marker-based screening of wheat germplasm for RWA resistance, future perspectives of wheat breeding in Uzbekistan, marker-assisted selection for abiotic stress tolerance, wheat stripe rust and its control strategies in Uzbekistan, epidemiology of the rust pathogens, pathogen characterization, and varietal resistance.

Aluminum decreases cadmium accumulation by down-regulating the expression of cadmium-related genes in wheat

Aluminum (Al) and cadmium (Cd) often coexist in the acidic soils of southern China, but their interactive effects remain unclear. In this study, this was examined in Al-resistant (Atlas 66) and Al-sensitive (Scout 66) wheat cultivars. The results showed that Al significantly alleviated the root growth of Al-tolerant Atlas 66 under Cd stress but had no effect on the root growth of Al-sensitive Scout 66 or the shoot growth of both cultivars. However, Al substantially decreased Cd accumulation in the roots and shoots of Atlas 66 and Scout 66. This could be attributed to the decreased uptake of Cd by the roots rather than the changes in Cd distribution in various organs or the Cd binding and adsorption of the cell wall. Using non-invasive micro-test technology, we further confirmed that Al and Cd co-exposure significantly inhibited the net Cd2+ influx into the roots of Atlas 66 and Scout 66 compared to Cd-only stress. Furthermore, the higher Cd2+ influx into roots should be responsible for the high Cd accumulation in the roots and shoots of Atlas66 than in those of Scout66 under Al and Cd co-exposure, which may be due to the higher Al accumulation in the roots of Al-sensitive Scout 66 that resulted in the larger decrease of negative charges on root surfaces. Finally, the effects of Al on the expression of Cd-related genes responsible for Cd uptake and translocation in wheat roots were investigated. The results have suggested that Al significantly downregulated the expression of TaNramp5 in Atlas 66 and the expression of TaNramp5, TaIRT1 and TaHMA2 in Scout66.

Dosage response to reduced height‐1 (Rht‐1) loss‐of‐function mutations and characterization of slender phenotype in hexaploid wheat

AbstractThe reduced height (Rht‐1) genes in wheat (Triticum aestivum L.) are integral in controlling plant height. Previous studies in other plant species have demonstrated that loss‐of‐function mutations in their orthologous Rht‐1 genes results in plants with a slender phenotype illustrated by increased plant heights, sterility, and a constitutive gibberellic acid (GA3) response; however, this phenotype has not been described in wheat. In this study, nonsense alleles occurring in the GRAS domain of Rht‐A1, B1, and D1 were combined to create single, double, and triple Rht‐1 mutants. Homozygous lines possessing none, one, two, or three Rht‐1 stop mutations were grown in replicated field trials in three environments to assess agronomic traits. Germination tests to measure GA3 responsiveness and gene expression analysis via RNA‐seq were also performed. Rht‐1 triple mutants exhibited a slender phenotype characterized by rapid growth, elongated coleoptiles and internodes, elongated spikes, decreased tiller and spikelet number, and sterile heads. The presence of a single functional Rht‐1 gene resulted in a normal phenotype. Differences in plant height among the Rht‐1 double mutants, Rht‐1 single mutants, and Rht‐1 all wild‐type dosages trended toward increased plant height with increased Rht‐1 stop mutation dosage. Differences in Rht‐1 homeolog gene expression did not equate to differences in plant height between the different Rht‐1 stop mutations.

Transcriptomic analysis of wheat reveals possible resistance mechanism mediated by Yr10 to stripe rust

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a catastrophic disease that threatens global wheat yield. Yr10 is a race-specific all-stage disease resistance gene in wheat. However, the resistance mechanism of Yr10 is poorly characterized. Therefore, to elucidate the potential molecular mechanism mediated by Yr10, transcriptomic sequencing was performed at 0, 18, and 48 h post-inoculation (hpi) of compatible wheat Avocet S (AvS) and incompatible near-isogenic line (NIL) AvS + Yr10 inoculated with Pst race CYR32. Respectively, 227, 208, and 4050 differentially expressed genes (DEGs) were identified at 0, 18, and 48 hpi between incompatible and compatible interaction. The response of Yr10 to stripe rust involved various processes and activities, as indicated by the results of Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Specifically, the response included photosynthesis, defense response to fungus, metabolic processes related to salicylic acid (SA) and jasmonic acid (JA), and activities related to reactive oxygen species (ROS). Ten candidate genes were selected for qRT-PCR verification and the results showed that the transcriptomic data was reliable. Through the functional analysis of candidate genes by the virus-induced gene silencing (VIGS) system, it was found that the gene TaHPPD (4-hydroxyphenylpyruvate dioxygenase) negatively regulated the resistance of wheat to stripe rust by affecting SA signaling, pathogenesis-related (PR) gene expression, and ROS clearance. Our study provides insight into Yr10-mediated resistance in wheat.

Modulation in gene expression and enzyme activity suggested the roles of monodehydroascorbate reductase in development and stress response in bread wheat

Monodehydroascorbate reductase (MDHAR) is a crucial enzymatic antioxidant of the ascorbate-glutathione pathway involved in reactive oxygen species scavenging. Herein, we identified 15 TaMDHAR genes in bread wheat. Phylogenetic analysis revealed their clustering into three groups, which are also related to the subcellular localization in the peroxisome matrix, peroxisome membrane, and chloroplast. Each TaMDHAR protein consisted of two conserved domains; Pyr_redox and Pyr_redox_2 of the pyridine nucleotide disulfide oxidoreductase family. The occurrence of diverse groups of cis-regulatory elements in the promoter region and their interaction with numerous transcription factors suggest assorted functions of TaMDHARs in growth and development and in light, phytohormones, and stress responses. Expression analysis in various tissues further revealed their importance in vegetative and reproductive development. In addition, the differential gene expression and enhanced enzyme activity during drought, heat, and salt treatments exposed their role in abiotic stress response. Interaction of MDHARs with various antioxidant enzymes and biochemicals related to the ascorbate-glutathione cycle exposed their synchronized functioning. Interaction with auxin indicated the probability of cross-talk between antioxidants and auxin signaling. The miR168a, miR169, miR172 and others interaction with various TaMDHARs further directed their association with developmental processes and stress responses. The current study provides extensive information about the importance of TaMDHARs, moreover, the precise role of each gene needs to be established in future studies.

Triticum durum Desf. is a valuable source for spring bread wheat genetic diversity enhancement

Background. Enhancement of the Triticum aestivum L. genetic diversity by means of alien chromatin, including that from Triticum durum Desf., is an important element in the breeding of bread wheat cultivars that meet modern requirements.Materials and methods. The study included the L153, L154 and L155 introgressive spring bread wheat lines produced from crosses between the spring bread wheat cultivars ‘L503’ and ‘L505’ and spring durum wheat cultivars ‘Yazi10’ and ‘Tarro’ developed in Mexico. Evaluation of these introgressive lines included phytopathological, phenological, genetic, and breadmaking analyses carried out with conventional methods both under open-air and laboratory conditions. Seventeen DNA markers were used to identify genes for resistance to Puccinia triticina Erikss. f. sp. tritici in the lines. The obtained data were statistically analyzed using the Agros-2.10 package of breeding and genetic programs.Results. Studying introgressive spring bread wheat lines L153, L154 and L155, developed with the participation of durum wheat cvs. ‘Yazi10’ and ‘Tarro’, showed that leaf rust resistance of these lines was induced by the Lr genes from durum wheat cultivars. The effect of the gene donor and the recipient cultivars on a number of useful agronomic traits was identified. The recipient cv. ‘L505’ was noted for its good combining abilities.Conclusion. Introgression of chromatin from durum wheat cultivars into the spring bread wheat gene pool made it possible to produce lines resistant to the local P. triticina population, as well as to some test clones of this pathogen. Such lines can be used as donors of the Lr genes. In addition, the L154 introgressive line combined good grain productivity and baking quality.

Common bunt in organic wheat: unravelling infection characteristics relevant for resistance breeding.

Common bunt caused by Tilletia tritici and T. laevis has re-emerged as a major threat to wheat yield and quality, especially in organic farming. Resistance against its causal agents is present in the wheat gene pool and provides the most economically efficient and sustainable way to combat the disease since seed treatments approved for organic farming are rare and do not always provide full protection. We tested a winter wheat diversity panel with 128 lines for common bunt resistance in Austria and Czechia, and evaluated the applicability of marker-assisted selection (MAS) via Kompetitive Allele-Specific PCR markers in genotypes with high variation in their genetic background. Field trials were conducted across two years and artificially inoculated with local bunt populations. The virulence patterns of these inocula differed between locations and only 15% of the tested genotypes showed stable resistance across test sites. Number and weight of bunt sori relative to the total number and weight of wheat grains in sampled ears revealed that partial infections of ears were frequently appearing. Forty-two breeding lines harboring combinations of four different resistance QTL were developed through MAS. Out of these, a quarter were resistant with a maximum of 5% common bunt incidence. On the other hand, only six out of 46 tested commercial cultivars and breeding lines showed no infection with common bunt, underlining the present scarcity of bunt-resistant cultivars for organic wheat production. By this study we showed that MAS is a useful tool to speed up the selection of resistant lines even in populations with highly diverse genetic backgrounds, and that it is efficient in pyramiding resistance loci and thereby improving the level of resistance.

TaGPX1-D overexpression provides salinity and osmotic stress tolerance in Arabidopsis

Glutathione peroxidases (GPXs) are known to play an essential role in guarding cells against oxidative stress by catalyzing the reduction of hydrogen peroxide and organic hydroperoxides. The current study aims functional characterization of the TaGPX1-D gene of bread wheat (Triticum aestivum) for salinity and osmotic stress tolerance. To achieve this, we initially performed the spot assays of TaGPX1-D expressing yeast cells. The growth of recombinant TaGPX1-D expressing yeast cells was notably higher than the control cells under stress conditions. Later, we generated transgenic Arabidopsis plants expressing the TaGPX1-D gene and investigated their tolerance to various stress conditions. The transgenic plants exhibited improved tolerance to both salinity and osmotic stresses compared to the wild-type plants. The higher germination rates, increased antioxidant enzymes activities, improved chlorophyll, carotenoid, proline and relative water contents, and reduced hydrogen peroxide and MDA levels in the transgenic lines supported the stress tolerance mechanism. Overall, this study demonstrated the role of TaGPX1-D in abiotic stress tolerance, and it can be used for improving the tolerance of crops to environmental stressors, such as salinity and osmotic stress in future research.

Type I MADS-box transcription factor TaMADS-GS regulates grain size by stabilizing cytokinin signalling during endosperm cellularization in wheat.

Grain size is one of the important traits in wheat breeding programs aimed at improving yield, and cytokinins, mainly involved in cell division, have a positive impact on grain size. Here, we identified a novel wheat gene TaMADS-GS encoding type I MADS-box transcription factor, which regulates the cytokinins signalling pathway during early stages of grain development to modulate grain size and weight in wheat. TaMADS-GS is exclusively expressed in grains at early stage of seed development and its knockout leads to delayed endosperm cellularization, smaller grain size and lower grain weight. TaMADS-GS protein interacts with the Polycomb Repressive Complex 2 (PRC2) and leads to repression of genes encoding cytokinin oxidase/dehydrogenases (CKXs) stimulating cytokinins inactivation by mediating accumulation of the histone H3 trimethylation at lysine 27 (H3K27me3). Through the screening of a large wheat germplasm collection, an elite allele of the TaMADS-GS exhibits higher ability to repress expression of genes inactivating cytokinins and a positive correlation with grain size and weight, thus representing a novel marker for breeding programs in wheat. Overall, these findings support the relevance of TaMADS-GS as a key regulator of wheat grain size and weight.