Regulation of carbohydrate metabolism during anther development in a thermo-sensitive genic male-sterile wheat line.

Bainong sterility (BNS) is a thermo-sensitive genic male sterile wheat line, characterised by anther fertility transformation in response to low temperature (LT) stress during meiosis, the failure of vacuole decomposition and the absence of starch accumulation in sterile bicellular pollen. Our study demonstrates that the late microspore (LM) stage marks the transition from the anther growth to anther maturation phase, characterised by the changes in anther structure, carbohydrate metabolism and the main transport pathway of sucrose (Suc). Fructan is a main storage polysaccharide in wheat anther, and its synthesis and remobilisation are crucial for anther development. Moreover, the process of pollen amylogenesis and the fate of the large vacuole in pollen are closely intertwined with fructan synthesis and remobilisation. LT disrupts the normal physiological metabolism of BNS anthers during meiosis, particularly affecting carbohydrate metabolism, thus determining the fate of male gametophytes and pollen abortion. Disruption of fructan synthesis and remobilisation regulation serves as a decisive event that results in anther abortion. Sterile pollen exhibits common traits of pollen starvation and impaired starch accumulation due to the inhibition of apoplastic transport starting from the LM stage, which is regulated by cell wall invertase TaIVR1 and Suc transporter TaSUT1.

Identification of ankyrin-transmembrane-type subfamily genes in Triticeae species reveals TaANKTM2A-5 regulates powdery mildew resistance in wheat.

The ankyrin-transmembrane (ANKTM) subfamily is the most abundant subgroup of the ANK superfamily, with critical roles in pathogen defense. However, the function of ANKTM proteins in wheat immunity remains largely unexplored. Here, a total of 381 ANKTMs were identified from five Triticeae species and Arabidopsis, constituting five classes. Among them, class a only contains proteins from Triticeae species and the number of ANKTM in class a of wheat is significantly larger than expected, even after consideration of the ploidy level. Tandem duplication analysis of ANKTM indicates that Triticum urartu, Triticum dicoccoides and wheat all had experienced tandem duplication events which in wheat-produced ANKTM genes all clustered in class a. The above suggests that not only did the genome polyploidization result in the increase of ANKTM gene number, but that tandem duplication is also a mechanism for the expansion of this subfamily. Micro-collinearity analysis of Triticeae ANKTMs indicates that some ANKTM type genes evolved into other types of ANKs in the evolution process. Public RNA-seq data showed that most of the genes in class d and class e are expressed, and some of them show differential responses to biotic stresses. Furthermore, qRT-PCR results showed that some ANKTMs in class d and class e responded to powdery mildew. Silencing of TaANKTM2A-5 by barley stripe mosaic virus-induced gene silencing compromised powdery mildew resistance in common wheat Bainongaikang58. Findings in this study not only help to understand the evolutionary process of ANKTM genes, but also form the basis for exploring disease resistance genes in the ANKTM gene family.

New SFT2-like Vesicle Transport Protein (SFT2L) Enhances Cadmium Tolerance and Reduces Cadmium Accumulation in Common Wheat Grains.

Cadmium (Cd) is one of the most toxic heavy metal elements to the environment, which seriously threatens the safe production of food crops. In this study, we identified a novel function of the cytomembrane TaSFT2L protein in wheat (Triticum aestivum). Expression of the TaSFT2L gene in yeast showed no transport activities for Cd, which could explain the role of TaSFT2L in metal tolerance. It was observed that increased autophagic activity in roots caused by silencing of TaSFT2L enhanced Cd tolerance. Transgenic wheat revealed that RNA interference (RNAi) lines enhanced the wheat growth concerning the increased shoot or root elongation, dry weight, and chlorophyll accumulation. Furthermore, RNAi lines decreased root-to-grain Cd translocation in wheat by nearly 68% and Cd accumulation in wheat grains by 53%. Meanwhile, the overexpression lines displayed a compromised growth response and increased Cd accumulation in wheat tissues, compared to wild type. These findings show that TaSFT2L is a key gene involved in regulation of Cd translocation in wheat, and its silencing to form transgenic wheat can inhibit Cd accumulation. This has the ability to alleviate the food chain-associated impact of environmental pollution on human health.

Genome-wide identification and characterization of the Lateral Organ Boundaries Domain (LBD) gene family in polyploid wheat and related species.

BACKGROUND: Wheat (Triticum aestivum) originated from three different diploid ancestral grass species and experienced two rounds of polyploidization. Exploring how certain wheat gene subfamilies have expanded during the evolutionary process is of great importance. The Lateral Organ Boundaries Domain (LBD) gene family encodes plant-specific transcription factors that share a highly conserved LOB domain and are prime candidates for this, as they are involved in plant growth, development, secondary metabolism and stress in various species. METHODS: Using a genome-wide analysis of high-quality polyploid wheat and related species genome sequences, a total of 228 LBD members from five Triticeae species were identified, and phylogenetic relationship analysis of LBD members classified them into two main classes (classes I and II) and seven subgroups (classes I a-e, II a and II b). RESULTS: The gene structure and motif composition analyses revealed that genes that had a closer phylogenetic relationship in the same subgroup also had a similar gene structure. Macrocollinearity and microcollinearity analyses of Triticeae species suggested that some LBD genes from wheat produced gene pairs across subgenomes of chromosomes 4A and 5A and that the complex evolutionary history of TaLBD4B-9 homologs was a combined result of chromosome translocation, polyploidization, gene loss and duplication events. Public RNA-seq data were used to analyze the expression patterns of wheat LBD genes in various tissues, different developmental stages and following abiotic and biotic stresses. Furthermore, qRT-PCR results suggested that some TaLBDs in class II responded to powdery mildew, regulated reproductive growth and were involved in embryo sac development in common wheat.