Chuan Xia

Brassinosteroid signaling kinases (BSKs) act as core signal transducers downstream of Brassinosteroid (BR) perception and integrate plant growth regulation with broad-spectrum biotic and abiotic stress tolerance. Despite well-established functional characterizations of BSK gene families in Arabidopsis thaliana and rice, comprehensive genome-wide profiling and salt response analysis of BSK homologs remain lacking in wheat. In this study, we systematically identified 18 TaBSK family members. Phylogenetic analysis separated wheat TaBSKs into three distinct evolutionary subgroups. The 18 TaBSK loci were unevenly distributed across 14 chromosomes derived from the A, B, and D subgenomes. Motif scanning uncovered 10 universal conserved amino acid motifs, including two signature functional domains: the tetratricopeptide repeat (TPR) and protein kinase catalytic domain (PKc). Intra-genomic collinearity analysis confirmed that segmental duplication constituted the primary evolutionary driver underlying TaBSK family expansion. Extensive cis-regulatory element profiling identified abundant hormone- and stress-responsive cis-motifs. Transcriptome profiling RNA-seq datasets revealed five TaBSK genes exhibiting significant differential transcription under salt stress. Specifically, TaBSK16, TaBSK17, and TaBSK18 were markedly upregulated following salt exposure. Collectively, this study delivers an evolutionary and transcriptional atlas of the wheat TaBSK family and provides candidate genes for functional validation and molecular breeding toward salt-tolerant wheat varieties. Collectively, this study explores the evolution and transcriptional patterns of the wheat TaBSK gene family and provides candidate genes for subsequent functional validation and molecular breeding of salt-tolerant wheat varieties.

Wheat is a globally important staple crop, whose growth and yield formation rely on the precise regulation of phytohormone signaling. The PR10/Bet v 1 (Pathogenesis-related protein 10/Betula verrucosa 1) family consists of conserved small-molecule ligand-binding proteins that participate in phytohormone signaling and plant development; however, systematic investigations of this family in wheat remain limited. Here, we performed a genome-wide identification of 75 PR10/Bet v 1 members in wheat, which were phylogenetically classified into three subfamilies: 21 known members belonging to the PYL (Pyrabactin resistance 1-like) subfamily, and 54 members assigned to two previously uncharacterized subfamilies. Bioinformatic analyses revealed that whole-genome/segmental duplication has driven the expansion of this gene family, which has evolved under strong purifying selection. Expression profiling and promoter analysis revealed differential expression patterns, along with abundant cis-acting elements responsive to multiple hormones. Quantitative RT-PCR (qRT-PCR) of 12 representative genes revealed marked transcriptional changes in several members within 1 h of treatment with BR (Brassinosteroid), ABA (Abscisic acid), CK (Cytokinin), or SA (Salicylic acid) suggesting that these genes may be directly involved in hormone-regulated processes. This study provides a fundamental framework for exploring the regulatory functions of the wheat PR10/Bet v 1 family, and valuable hormone-responsive candidate genes for the genetic improvement of wheat agronomic traits.

Alternative splicing (AS) is a crucial post-transcriptional regulatory mechanism that enhances transcript and proteome diversity. However, AS in common wheat (Triticum aestivum) remains understudied due to the large and complex genome of this crop. Full-length transcriptome sequencing, which provides long, high-quality reads, offers a powerful tool for analyzing AS in wheat. In this study, we used the PacBio Sequel platform to sequence full-length transcripts from 5 wheat tissues (root, stem, leaf, spike, and grain) of the cultivar Aikang58 (AK58). We identified 560,631 isoforms from 86,073 genes, with 76.7% of genes producing multiple isoforms and 45.34% undergoing AS events (ASEs). Tissue-specific analysis revealed differences in the number and function of AS genes (ASGs), underscoring the potential role of AS in tissue differentiation. A comparison across the 3 wheat subgenomes showed similar numbers of ASGs and ASEs but distinct functional patterns, suggesting that AS is involved in subgenomic divergence. We also examined AS in genes linked to key agronomic traits, demonstrating association with trait regulation. These findings enhance our understanding of the adaptability and post-transcriptional gene regulation in wheat, offering insights for future research and breeding efforts.

Leaf width is an important component of plant architecture that strongly affects light capture during photosynthesis and thus grain yield, particularly under dense planting conditions. However, the genetic and molecular mechanisms regulating leaf width in wheat (Triticum aestivum L.) remain unclear. Here, we identified the narrow-leaf mutant nl1 with fewer small veins than the wild-type and isolated the narrow-leaf gene Narrow Leaf 1 (NL1) through a combination of map-based cloning and bulked segregant exome capture sequencing (BSE-seq). NL1 encodes CELL DIVISION CYCLE 48-like (CDC48-like). A single Ser-to-Phe amino acid substitution in this protein led to a narrow-leaf phenotype. Transcriptomic analysis and measurement of endogenous phytohormone levels in nl1 vs. the wild-type suggested that NL1 might regulate cell division and the cytokinin pathway to control leaf width. Haplotype analysis showed that Hap2 of NL1 has been selected during wheat breeding. These findings provide insights into the genetic and molecular mechanisms underlying the role of NL1 in regulating leaf width and point to the potential of Hap2 for improving wheat plant architecture.

Main conclusion Overexpression of OsNRT1.1A promotes early heading and increases the tolerance in wheat under nitrogen deficiency conditions. Abstract The application of inorganic nitrogen (N) fertilizers is a major driving force for crop yield improvement. However, the overuse of fertilizers significantly raises production costs and leads to environmental problems, making it critical to enhance crop nitrogen use efficiency (NUE) for the sake of sustainable agriculture. In this study, we created a series of transgenic wheat lines carrying the rice OsNRT1.1A gene, which encodes a nitrate transporter, to investigate its possible application in improving NUE in wheat. The transgenic wheat exhibited traits such as early maturation that were highly consistent with the overexpression of OsNRT1.1A in Arabidopsis and rice. However, we also observed that overexpression of the OsNRT1.1A gene in wheat can facilitate the growth of roots under low N conditions but has no effect on other aspects of growth and development under normal N conditions. Thus, it may lead to the improvement of wheat low N tolerance,which is different from the effects reported in other plants. A field trial analysis showed that transgenic wheat exhibited increased grain yield per plant under low N conditions. Moreover, transcriptome analysis indicated that OsNRT1.1A increased the expression levels of N uptake and utilization genes in wheat, thereby promoting plant growth under low N conditions. Taken together, our results indicated that OsNRT1.1A plays an important role in improving NUE in wheat with low N availability.

Key message A chromosome fragment influencing wheat heading and grain size was identified using mapping of m406 mutant. The study of TaFPF1 in this fragment provides more insights into wheat yield improvement. Abstract In recent years, wheat production has faced formidable challenges driven by rapid population growth and climate change, emphasizing the importance of improving specific agronomic traits such as heading date, spike length, and grain size. To identify potential genes for improving these traits, we screened a wheat EMS mutant library and identified a mutant, designated m406, which exhibited a significantly delayed heading date compared to the wild-type. Intriguingly, the mutant also displayed significantly longer spike and larger grain size. Genetic analysis revealed that a single recessive gene was responsible for the delayed heading. Surprisingly, a large 46.58 Mb deletion at the terminal region of chromosome arm 2DS in the mutant was identified through fine mapping and fluorescence in situ hybridization. Thus, the phenotypes of the mutant m406 are controlled by a group of linked genes. This deletion encompassed 917 annotated high-confidence genes, including the previously studied wheat genes Ppd1 and TaDA1, which could affect heading date and grain size. Multiple genes in this region probably contribute to the phenotypes of m406. We further investigated the function of TaFPF1 using gene editing. TaFPF1 knockout mutants showed delayed heading and increased grain size. Moreover, we identified the direct upstream gene of TaFPF1 and investigated its relationship with other important flowering genes. Our study not only identified more genes affecting heading and grain development within this deleted region but also highlighted the potential of combining these genes for improvement of wheat traits.