In plants, 14-3-3 proteins are recognized as mediators of signal transduction and function in both development and stress response. However, there are only a few preliminary functional researches in the C4 crop foxtail millet. Here, phylogenetic analysis categorized foxtail millet 14-3-3s (SiGRFs) into 10 discrete groups (Clusters I to X). Transcriptome and qPCR analyses showed that all the SiGRFs responded to at least one abiotic stress. All but one SiGRF-overexpressing (OE) Arabidopsis thaliana line (SiGRF1) exhibited insensitivity to abiotic stresses during seed germination and seedling growth. Compared with the Col-0 wild-type, SiGRF1-OEs had slightly lower germination rates and smaller leaves. However, flowering time of SiGRF1-OEs occurred earlier than that of Col-0 under high-salt stress. Interaction of SiGRF1 with a foxtail millet E3 ubiquitin-protein ligase (SiRNF1/2) indicates that the proteinase system might hydrolyze SiGRF1. Further investigation showed that SiGRF1 localized in the cytoplasm, and its gene was ubiquitously expressed in various tissues throughout various developmental stages. Additionally, flowering-related genes, WRKY71, FLOWERING LOCUS T, LEAFY, and FRUITFULL, in SiGRF1-OEs exhibited considerably higher expression levels than those in Col-0 under salinity-stressed conditions. Results suggest that SiGRF1 hastens flowering, thereby providing a means for foxtail millet to complete its life cycle and avoid further salt stress.

Summary: Heat stress caused by increasing global temperature has become a major factor limiting yield in wheat. Heat shock transcription factors (Hsfs), as the primary regulators in plant responses to heat stress, play essential roles in modulating both basal and acquired thermotolerance in plants. However, the underlying molecular mechanisms remain to be elucidated. By analysing the wheat transcriptome after subjecting wheat to heat treatments for different time intervals, we identified gene TaHsfA2h that showed a significant positive regulatory response to heat stress. Heat stress tolerance was enhanced by overexpression of TaHsfA2h and constrained by its RNA interference. RNA‐seq analysis demonstrated that the overexpression of TaHsfA2h significantly enhanced the expression levels of genes involved in ABA and ROS signalling pathways. Additionally, we identified TaABF5b , a critical regulatory factor in the ABA signalling pathway, as being capable of modulating the expression of TaHsfA2h . Notably, TaHsfA2h interacted with TaHsfC2a both in vivo and in vitro . Similarly, overexpression of TaHsfC2a significantly enhanced heat stress tolerance, whereas knockout dramatically reduced tolerance. The presence of TaHsfC2a significantly enhanced the regulatory activity of TaHsfA2h. TaHsfA2h and TaHsfC2a can co‐regulate the expression levels of heat stress tolerance‐related genes, including TaNCED2B , TaPOD4 and TaHSP26 , thereby enhancing wheat's tolerance to heat stress. Overall, our findings revealed a positive regulatory function of the ABF5b‐HsfA2h/HsfC2a‐NCED2b/POD4/HSP26 module on wheat heat stress tolerance. This discovery further expanded the functionality of a plant heat stress response model, providing a theoretical foundation for the development of heat‐tolerant wheat varieties.

The lateral organ boundaries domain (LBD) genes, as the plant-specific transcription factor family, play a crucial role in controlling plant architecture and stress tolerance. Although it has been thoroughly characterized in many species, the LBD family was not well studied in wheat. Here, the wheat LBD family was systematically investigated through an in silico genome-wide search method. A total of 90 wheat LBD genes (TaLBDs) were identified, which were classified into class I containing seven subfamilies, and class II containing two subfamilies. Exon–intron structure, conserved protein motif, and cis-regulatory elements analysis showed that the members in the same subfamily shared similar gene structure organizations, supporting the classification. Furthermore, the expression patterns of these TaLBDs in different types of tissues and under diverse stresses were identified through public RNA-seq data analysis, and the regulation networks of TaLBDs involved were predicted. Finally, the expression levels of 12 TaLBDs were validated by quantitative PCR (qPCR) analysis and the homoeologous genes showed differential expression. Additionally, the genetic diversity of TaLBDs in the landrace population showed slightly higher than that of the genetically improved germplasm population while obvious asymmetry at the subgenome level. This study not only provided the potential targets for further functional analysis but also contributed to better understand the roles of LBD genes in regulating development and stress tolerance in wheat and beyond.

Background: Development of wheat cultivars with multiple disease resistance and high quality are major objectives in modern wheat breeding programs. Gene stacking is an efficient approach to achieve this target. In this study, we pyramided yellow rust resistance gene (Yr26), powdery mildew resistance gene (ML91260) and high-molecular-weight glutenin subunits Dx5 + Dy10 into the dwarf mutant of an elite wheat cultivar, Xiaoyan22. Results: Six pyramided wheat lines were obtained by molecular marker-assisted selection (MAS) and field evaluation of disease resistance. The desirable agronomic traits of pyramided lines, their identity with the original cultivar Xiaoyan22 except for plant height, tiller number and disease resistance, was achieved in this study. Meanwhile, the yield of pyramided lines is higher than Xiaoyan22 in the field test. In addition, analysis of flour quality indicated that the dough stability time of pyramided lines was longer than that of Xiaoyan22. Conclusions: Six pyramided wheat lines with two disease resistance and high quality were achieved in this study. It is feasible to improve multiple agronomic traits simultaneously by rational application of MAS.

Background: Lignin is one of the main components of the cell wall and is directly associated with plant development and defence mechanisms in plants, especially in response to Fusarium graminearum (Fg) infection. Caffeoyl-coenzyme A O-methyltransferase (CCoAOMT) is the main regulator determining the efficiency of lignin synthesis and composition. Although it has been characterized in many plants, to date, the importance of the CCoAOMT family in wheat is not well understood. Results: Here, a total of 21 wheat CCoAOMT genes (TaCCoAOMT) were identified through an in silico genome search method and they were classified into four groups based on phylogenetic analysis, with the members of the same group sharing similar gene structures and conserved motif compositions. Furthermore, the expression patterns and co-expression network in which TaCCoAOMT is involved were comprehensively investigated using 48 RNA-seq samples from Fg infected and mock samples of 4 wheat genotypes. Combined with qRT-PCR validation of 11 Fg-responsive TaCCoAOMT genes, potential candidates involved in the FHB response and their regulation modules were preliminarily suggested. Additionally, we investigated the genetic diversity and main haplotypes of these CCoAOMT genes in bread wheat and its relative populations based on resequencing data. Conclusions: This study identified and characterized the CCoAOMT family in wheat, which not only provided potential targets for further functional analysis, but also contributed to uncovering the mechanism of lignin biosynthesis and its role in FHB tolerance in wheat and beyond.

Heat stress is a severe environmental stress that affects plant growth and reduces yield. Bax inhibitor-1 (BI-1) is a cytoprotective protein that is involved in the response to biotic and abiotic stresses. The Arabidopsis (Arabidopsis thaliana) BI-1 mutants atbi1–1 and atbi1–2 are hypersensitive to heat stress, and AtBI-1 overexpression rescues thermotolerance deficiency in atbi1 plants. Nevertheless, the mechanism of BI-1 in plant thermotolerance is still unclear. We identified a wheat (Triticum aestivum L.) BI-1 gene, TaBI-1.1, which was highly upregulated in an RNA sequencing (RNA-seq) analysis of heat-treated wheat. The upregulation of TaBI-1.1 under heat stress was further demonstrated by real time quantitative PCR (qRT-PCR) and β-glucuronidase (GUS) staining. Compared with the wild type Col-0, the atbi1–2 mutant is hypersensitive to heat stress, and constitutive expression of TaBI-1.1 in atbi1–2 (35S::TaBI-1.1/ atbi1–2) rescued the deficiency of atbi1–2 under heat stress. Furthermore, we identified TaFKBP62 as a TaBI-1.1-interacting protein that co-localized with TaBI-1.1 on the endoplasmic reticulum (ER) membrane and enhanced heat stress tolerance. Additionally, HSFA2, HSFB1, ROF1, HSP17.4B, HSP17.6A, HSP17.8, HSP70B, and HSP90.1 expression levels were suppressed in atbi1–2 plants under heat stress. In contrast, 35S::TaBI-1.1/atbi1–2 relieved the inhibitory effect of AtBI-1 loss of function. TaBI-1.1 interacted with TaFKBP62 and co-localized with TaFKBP62 on the ER membrane. Both TaBI-1.1 and AtBI-1 regulated the expression of heat-responsive genes and were conserved in plant thermotolerance.