A genotypic pattern for breeding wheat with ideal plant architecture. Breeding wheat with reduced leaf angle represents a promising strategy for developing lines tolerant to high planting density, mitigating the adverse effects of shade avoidance and thus increasing yield potential. However, the molecular mechanisms underlying the reduced leaf angle phenotype remain poorly understood. In this study, a wheat mutant with a reduced leaf angle, designated lad1 and exhibiting impaired sensitivity to brassinosteroids (BRs), was isolated from an EMS-induced mutant library. Phenotypic analysis revealed that the reduced leaf angle in lad1 plants is due to a decrease in the size of lamina joint cells. Genetic mapping and cloning identified Talad1-A1, a single recessive nuclear gene located on chromosome 2A, is responsible for the variation in leaf angle. Furthermore, Rht8 and Rht-D1b have been shown to contribute significantly to leaf angle regulation. These findings deepen our understanding of the genetic and molecular mechanisms controlling leaf angle in wheat and provide a potential molecular selection strategy for the developing elite wheat varieties adapted to high-density planting.

Leaf area index (LAI) is a key determinant of canopy structure, photosynthetic capacity, and biomass accumulation in wheat, thereby playing a critical role in regulating final grain yield (GY). Accurate and rapid estimation of LAI and GY is essential for precision crop management and high-yield breeding. Leveraging the capacity of multi-task learning (MTL) to exploit intrinsic trait correlations for improved prediction accuracy. This study developed an integrated framework based on canopy hyperspectral remote sensing to simultaneously forecast winter wheat LAI and GY across multiple growth stages and environments. To establish a benchmark, four single-task algorithms, including ridge regression (RR), random forest, support vector regression, and partial least squares regression, were initially evaluated. Among these algorithms, RR exhibited the most robust performance, achieving independent testing coefficients of determination (R2)of 0.57 for GY and 0.70 for LAI. Subsequently, the MTL framework integrated three optimization strategies: task-weight balancing, NDVI fusion, and using LAI as an auxiliary variable. While initial weight optimization yielded moderate gains (R2 = 0.61 for GY, incorporating NDVI boosted LAI prediction accuracy to an R2 of 0.86). Furthermore, integrating LAI as an auxiliary trait notably enhanced GY prediction, achieving an R2 of 0.75 and RMSE of 0.25 kg/plot. Compared to the single-task RR baseline, the fully integrated MTL framework improved predictive performance, increasing the R2 for GY from 0.57 to 0.75 and for LAI from 0.70 to 0.86. These results demonstrate that the proposed MTL approach effectively captures canopy-yield associations, offering a robust tool for rapid field-scale phenotyping and precision yield forecasting.

Establishing a technical system for in vitro mutagenesis and salt tolerance screening of wheat microspores is crucial for accelerating the homozygous stabilization of mutant progeny, creating novel salt‑tolerant wheat germplasm, and enabling the effective utilization of saline‑alkali land. Due to technical limitations of in vitro microspore culture in wheat, studies combining wheat microspore culture with in vitro mutagenesis and salt stress screening have not been reported. Based on a previously established genotype‑dependent wheat microspore culture system, our laboratory developed a technical system integrating microspore‑based X‑ray mutagenesis and salt stress screening, thereby providing a new technical approach for accelerating the development of salt‑tolerant wheat germplasm. To determine the optimal X-ray irradiation dose, microspores from the cultivars Shi 4185 and HeNong 6425 were exposed to 0, 3, 5, 10, 15, and 20 Gy of X-ray radiation. The LD₅₀ values for Shi 4185 and HeNong 6425 were 3 Gy and 4 Gy, respectively. To determine the NaCl concentration for in vitro salt tolerance screening of microspores, callus induction and differentiation were carried out on media supplemented with a range of NaCl concentrations. Adding 51 mM NaCl to the induction medium reduced regenerated plants per anther by 62.95

Spikelet degeneration and pollen sterility are primary constraints on grain set in wheat (Triticum aestivum L.), yet their molecular underpinnings remain poorly defined. We characterized degenerated spikelets 1 (ds1), a wheat mutant displaying apical spikelet degeneration and middle spikelet sterility. Relative to wild type, ds1 exhibited a 17.0% reduction in spike length, an 88.8% decline in grain-bearing spikelets, and a 93.6% drop in grain number per spike. Fine mapping localized the causal locus to chromosome 3BL, where DS1, encoding a cysteine-rich receptor-like kinase, was identified as the causal gene and found to be strongly downregulated in degenerated spikelets. Concordantly, multiple MADS-box transcription factors were transcriptionally suppressed in ds1 degenerated spikelets. Histological analysis revealed anther shrinkage, disrupted boundaries between anther wall layers, and defective cuticle structure. Excessive reactive oxygen species accumulated in the anther outer wall, triggering programmed cell death. Loss of cuticular wax on the anther surface, combined with premature tapetal degradation, produced hollow anther locules, aberrant pollen exine layering, and failure of microspore maturation, culminating in sterility. Together, these findings demonstrate that coordinated regulation of PCD, tapetal development, and pollen exine formation is indispensable for normal spikelet and floret development in wheat.

The development of reproductive organs plays a vital role in the production of gametes. However, the regulators of this process are poorly understood in wheat. Here, we identified a wheat sterile mutant ste with indehiscent anthers and shrunken pollen grains. Cytological analysis suggested that the tapetum cells degenerated earlier; Ubisch bodies exhibited abnormal shapes, while the microspore mother cells displayed meiosis defects, leading to the failure of tetrads formation in the ste. Bulked segregant analysis (BSA) and map-based cloning indicated that the TaAGO5c encoding an Argonaute protein is responsible for the sterility in ste. Gene editing-mediated knockout of three TaAGO5c homeologous genes resulted in a severely decreased self-seeding rate, confirming its function in reproductive development. TaAGO5c was predominantly expressed in the young spikes and anthers from the unicellular microspore stage to mature pollen stage. Subcellular localization in wheat protoplasts suggested that TaAGO5c is localized in the cytoplasm. Transcriptome sequencing analysis suggested that DEGs between the ste and control in the 30-40 mm and 60-70 mm young spikes were significantly enriched in several pathways associated with tapetum development and meiosis. Furthermore, some key genes related to these processes were downregulated in the ste mutant, which may be responsible for the abnormal development of tapetum and microspore. These results collectively suggest that TaAGO5c is a crucial regulator in reproductive development of wheat. This study also provides new insights into the genetic regulation of tapetum cells and Ubisch bodies development in wheat.

The number of spikelets is a key factor affecting wheat grain yield. We obtained a winter wheat mutant apical spikelet degeneration 1 (asd1). The apical spikelets of asd1 exhibited delayed development starting from the anther septum formation stage, showing a distinct degenerative phenotype during the tetrad stage. Reactive oxygen species (ROS) detection revealed that superoxide dismutase (SOD) enzyme activity was significantly elevated in the degenerated apical spikelets of asd1, accompanied by hydrogen peroxide (H2O2) accumulation and membrane lipid peroxidation, which resulted in redox imbalance within the cells. The catalase isozyme gene CAT2 and peroxidase genes POD1, POD5, POD8, POD12, and POD21 showed significant expression differences in the degenerated spikelets, leading to a burst of ROS that disrupted the redox homeostasis in the asd1 apical spikelets. At the tetrad stage, the asd1 apical spikelets exhibit PCD-like characteristics, accompanied by disruption of hormonal pathways. The expression patterns of key factors in the biosynthesis and signaling pathways of jasmonic acid (JA), abscisic acid (ABA), and auxin (IAA) were significantly altered, thereby perturbing the hormonal network within the apical spikelet. The expression patterns of known genes on spike development did not align with the apical spikelet degeneration in asd1, indicating that the degeneration was controlled by a novel gene. Our findings not only enhance the understanding of bidirectional interaction between ROS and hormones, but also provide valuable data for subsequent research on the genetic basis and regulatory mechanisms of apical spikelet development in wheat.

Heading date (HD) in wheat determines geographic adaptation, seasonal performance, and ultimately affects yield and quality. However, the genetic regulation of HD remains unclear. Here, we identified an Ethyl Methane Sulfonate (EMS)-induced wheat mutant, je0072, which headed two days earlier than the wild-type (WT) cultivar Jing411 without significant changes in yield components. Bulked segregant analysis (BSA) using an F2 population of 618 individuals identified the early-heading locus to the long arm of chromosome 5D. Genetic fine mapping further narrowed the locus to a 460-kb interval containing 10 high-confidence genes based on the Chinese Spring v2.1 reference genome. Sequence variation analysis identified a candidate gene, TaBGLU1-5D, encoding β-glycosyl hydrolase 1, which harbored a T-to-C substitution at position 31. Functional validation using independent mutants confirmed the role of TaBGLU1-5D in regulating HD. Transcriptome sequencing revealed that differentially expressed genes (DEGs) between WT and je0072 spikes at the heading stage were significantly enriched in starch and sucrose metabolism pathways. Weighted Gene Co-expression Network Analysis (WGCNA) further identified MADS-box transcription factor TaMADS26 as a regulatory hub associated with TaBGLU1-5D. We also found that TaBGLU1-5D modulates expression of key heading date-related genes, including VRN1, VRN3, and VRT2, thereby influencing HD. These results provide new insights into the genetic control of HD in wheat, and offer valuable resources for HD optimization in breeding programs.

Wheat yield mainly depends on thousand-grain weight, spike number per unit, and grain number per spike. Since fertility is directly related to seed setting rate and grain number, the discovery of novel genes and alleles affecting male or female sterility is essential for advancing the genetic understanding of wheat fertility. Here we identified a wheat mutant on anther–stigma development (asd), exhibiting both male and female sterility with thin shriveled non-dehiscent anthers that failed to release pollen, as well as visorless stigmas. Cytological examination of asd showed a lack of cutin polymer on anther surfaces and extensive microspore mother cell degeneration leading to pollen deficiency. Using MutMap+ and exome capture sequencing, we mapped one target gene on chromosome 2D, narrowing it a 1.62-Mb interval, and identifying TraesCS2D03G0987000 (TaTPR1), which encodes a conserved TOPLESS-related protein, as the candidate gene. TaTPR1 harbored a single base mutation (G > A) at the junction of the 6th intron and 7th exon, which disrupted splicing resulting in three transcripts. TaTPR1 expression levels were elevated in mutant anthers and ovaries, with subcellular localization confirming its presence in the nucleus and cytoplasm. Various allelic mutations within TaTPR1 exerted distinct impacts on pollen fertility and stigma development and led to reduced self-setting rates, which verified TaTPR1 to be the target gene. This study identified a crucial novel gene affecting both male and female sterility in wheat, which offers new insights into fertility mechanisms.

Heading date (HD) is a critical agronomic trait that influences wheat’s adaptation to environmental conditions and plays a pivotal role in yield stability. In this study, an early-heading mutant jg1489 was identified following γ-ray irradiation of the wild type (WT) wheat variety Jing411. This mutant headed 2–3 days earlier than the WT, with no significant differences in other yield-related traits. Bulked Segregant Analysis (BSA), genetic linkage analysis of the F2 population from a cross between the WT and mutant, and phenotypic validation in F2:3 lines were used to finely map the HD gene to a 12.4-Mb region on chromosome 5B. Transcriptome analysis of developing spikes from both WT and jg1489 at three key developmental stages revealed that differentially expressed genes (DEGs) were significantly enriched in pathways related to photosynthesis and photosynthesis-antenna proteins, suggesting a potential role in photosynthetic regulation. Within the mapped region, six high-probability candidate genes were identified based on sequence variation and expression patterns. Functional annotation, supported by studies of homologs in other species, highlighted three genes encoding serine proteases, bromodomain-containing protein, and UTP-glucose-1-phosphate uridylyltransferase as the most likely regulators of HD. These findings provide valuable insights into the genetic regulation of HD in wheat and support the development of new wheat varieties with optimized heading times.

Tiller number is a crucial determinant of grain yield in wheat (Triticum aestivum L.), and identifying functional alleles can enhance our understanding of wheat tiller development. Here, we describe the ot2 wheat mutant, which exhibits a 91% reduction in tiller number compared to the wild type and displays inhibited tiller bud differentiation from the 2-3 leaf stage. Bulked segregant analysis combined with exon sequencing mapped the Taot2 gene to chromosome 1BL. Fourteen kompetitive allele-specific PCR markers were developed and utilized to narrow down the region containing Taot2 to a 2.22 Mb interval. This region encompasses 39 high-confidence genes. Through transcriptomic analysis and functional gene investigation, TraesCS1B03G1126300 was identified as the candidate gene, encoding an auxin-responsive protein of the auxin/indole-3-acetic acid family. Our findings provide the foundation for map-based cloning of Taot2, a novel wheat tiller gene, and offer valuable insights into wheat tiller bud initiation.

Plant height determines lodging resistance and is closely linked to yield stability in wheat. In this study, we identified two semi-dwarf wheat mutants, designated je0370 and je0344, using the winter wheat cultivar Jing411 as the wild type (WT). Field experiments revealed that the plant height of these two mutants was significantly lower than that of the WT. In contrast, the thousand-grain weight was significantly higher in je0370 but lower in je0344 compared to the WT. Bulk Segregant Analysis (BSA) based on exome capture sequencing indicated that the gene responsible for height reduction is located on chromosome 4B. Further genetic linkage analysis mapped the dwarf gene to the interval of 29.26-48.61 Mb on chromosome 4B, corresponding to a genetic distance of 10.79 cM. This region encompasses the Rht1 gene; we subsequently sequenced the Rht1 gene in je0370 and je0344 and identified a C-T mutation at position 190 bp, resulting in a truncation of the DELLA domain in both mutants. Further analysis using Cleaved Amplified Polymorphic Sequences (CAPS) markers in F2 populations demonstrated that plants with homozygous Rht1 mutations exhibited significantly reduced plant height and thousand-grain weight, while heterozygous plants displayed intermediate effects. However, the mutation did not significantly affect spikelet number, effective spike number, or spike length. These findings conclusively demonstrate that the Rht1 mutation is responsible for plant dwarfism and reduced grain weight, without substantial impacts on other yield components. This study provides invaluable insights into the utilization of Rht1 in wheat breeding.

Heavy ion beam irradiation is a potent mutagenic technique for developing new germplasm resources and breeding novel plant varieties. However, the biological effects and molecular variations caused by different dosages of heavy ion beam irradiation in crops are still not well understood. In this study, we investigated the biological effects and molecular variations in the M1 generation of wheat, along with extensive phenotype screening in the M2 generation, to thoroughly assess the mutagenic impact of carbon-ion beam irradiation. Our findings indicate that radiation doses of 60–120 Gy significantly reduced seedling height and root length, with a 50

Premature senescence has a significant impact on the yield and quality of wheat crops. The process is controlled by multiple and intricate genetic pathways and regulatory elements, whereby the discovery of additional mutants provides important insights into the molecular basis of this important trait. Here, we developed a premature senescence wheat mutant je0874, its leaves started to show yellow before heading stage; with plant growth and development, the degree of yellowing worsened rapidly, and chlorophyll content in flag leaf was reduced by 93.8 % at 15 days after heading, all other leaves became dryness at the grain filling stage. In the mutant, the reactive oxygen species (ROS) and its metabolites increased up to 34.8-47.3 %, while activities of ROS scavenging enzymes were reduced by 62.7-96.7 %. Premature senescence resulted in a reduction of thousand grain weight by over 50 %. Genetic analysis showed the mutation of senescence was controlled by a single recessive gene, and target gene was finely mapped to a 338 kb region of the long arm of chromosome 2D. This region contained a total of 6 annotated genes, while only gene TraesFLD2D01G513900 carried a SNP mutation. The gene contained an NBS-LRR domain, we named it Taps1. Allelic mutants of Taps1 exhibited a lesion mimic phenotype, and the mutant allele resulted in cell death in tobacco, which represent a novel gene controlling wheat senescence. Two haplotypes were identified in 180 accessions, which did not lead to cell death. These results contribute to increase our understanding of the regulation of premature plant senescence.

Vernalization and photoperiod pathways converging at FT1 control the transition to flowering in wheat. Here, we identified a gain-of-function mutation in FT-D1 that results in earlier heading date (HD), and shorter plant height and spike length in the gamma ray-induced eh1 wheat mutant. Knockout of the wild-type and overexpression of the mutated FT-D1 indicate that both alleles are functional to affect HD and plant height. Protein interaction assays demonstrated that the frameshift mutation in FT-D1eh1 exon 3 led to gain-of-function interactions with 14-3-3A and FDL6, thereby enabling the formation of florigen activation complex (FAC) and consequently activating a flowering-related transcriptomic programme. This mutation did not affect FT-D1eh1 interactions with TaNaKR5 or TaFTIP7, both of which could modulate HD, potentially via mediating FT-D1 translocation to the shoot apical meristem. Furthermore, the 'Segment B' external loop is essential for FT-D1 interaction with FDL6, while residue Y85 is required for interactions with TaNaKR5 and TaFTIP7. Finally, the flowering regulatory hub gene, ELF5, was identified as the FT-D1 regulatory target. This study illustrates FT-D1 function in determining wheat HD with a suite of interaction partners and provides genetic resources for tuning HD in elite wheat lines.

>Dear Editor,The world faces unprecedented challenges for crop yield improvement to feed an expanding human population under limited agricultural resources and an increasingly erratic climate(Wheeler and von Braun, 2013). Bread wheat is one of the most widely cultivated cereal crops, with both grain and flag leaf morphologies determining final yield potential(Xie et al., 2015; Zanella et al., 2023). Candidate genes affecting these traits are therefore highly desirable targets for breeding programs.

Plant height is one of the most critical factors influencing wheat plant architecture, and the application of Green Revolution genes has led to a reduction in plant height and an increase in yield. Discovering new dwarfing genes and alleles can contribute to enhance the genetic diversity of wheat. Here we obtained an EMS induced dwarf wheat mutant je0166 with increased grain weight, which exhibited a reduction in plant height ranging from 46.47

Tiller number greatly contributes to grain yield in wheat. Using ethylmethanesulfonate mutagenesis, we previously discovered the oligo-tillering mutant ot1 . The tiller number was significantly lower in ot1 than in the corresponding wild type from the early tillering stage until the heading stage. Compared to the wild type, the thousand-grain weight and grain length were increased by 15.41% and 31.44%, respectively, whereas the plant height and spike length were decreased by 26.13% and 37.25%, respectively. Transcriptomic analysis was conducted at the regreening and jointing stages to identify differential expressed genes (DEGs). Functional enrichment analysis with the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases showed differential expression of genes associated with ADP binding, transmembrane transport, and transcriptional regulation during tiller development. Differences in tiller number in ot1 led to the upregulation of genes in the strigolactone (SL) and abscisic acid (ABA) pathways. Specifically, the SL biosynthesis genes DWARF ( D27 ), D17 , D10 , and MORE AXILLARY GROWTH 1 ( MAX1 ) were upregulated by 3.37- to 8.23-fold; the SL signal transduction genes D14 and D53 were upregulated by 1.81- and 1.32-fold, respectively; the ABA biosynthesis genes 9 - CIS - EPOXICAROTENOID DIOXIGENASE 3 ( NCED3 ) and NCED5 were upregulated by 1.66- and 3.4-fold, respectively; and SNF1-REGULATED PROTEIN KINASE2 ( SnRK2 ) and PROTEIN PHOSPHATASE 2C ( PP2C ) genes were upregulated by 1.30- to 4.79-fold. This suggested that the tiller number reduction in ot1 was due to alterations in plant hormone pathways. Genes known to promote tillering growth were upregulated, whereas those known to inhibit tillering growth were downregulated. For example, PIN-FORMED 9 ( PIN9 ), which promotes tiller development, was upregulated by 8.23-fold in ot1 ; Ideal Plant Architecture 1 ( IPA1 ), which inhibits tiller development, was downregulated by 1.74-fold. There were no significant differences in the expression levels of TILLER NUMBER 1 ( TN1 ) or TEOSINTE BRANCHED 1 ( TB1 ), indicating that the tiller reduction in ot1 was not controlled by known genes. Our findings provide valuable data for subsequent research into the genetic bases and regulatory mechanisms of wheat tillering.

Flag leaf angle is one of the key target traits in high yield wheat breeding, a smaller flag leaf angle reduces shading and enables plants to grow at a higher density, which increases yield. Here we identified a mutant, je0407, with an 84.34 %–89.35 % smaller flag leaf angle compared with the wild type. The mutant also had an abnormal lamina joint and no ligule or auricle. Genetic analysis indicated that the ligule was controlled by two recessive genes, which were mapped to chromosomes 2AS and 2DL. The mutant allele on chromosome 2AS was named Tafla1b, and it was fine mapped to a 1 Mb physical interval. The mutant allele on chr. 2DL was identified as Taspl8b, a novel allele of TaSPL8 with a missense mutation in the second exon, which was used to develop a cleaved amplified polymorphic sequence marker. F3 and F4 lines derived from crosses between Jing411 and je0407 were genotyped to investigate interactions between the Tafla1b and Taspl8b alleles. Plants with the Tafla1b/Taspl8a genotype had 58.41 %–82.76 % smaller flag leaf angles, 6.4 %–24.9 % shorter spikes, and a greater spikelet density (0.382 more spikelets per cm) compared with the wild type. Plants with the Tafla1a/Taspl8b genotype had 52.62 %–82.24 % smaller flag leaf angles and no differences in plant height or spikelet density compared with the wild type. Tafla1b/Taspl8b plants produced erect leaves with an abnormal lamina joint. The two alleles had dosage effects on ligule formation and flag leaf angle, but no significant effect on thousand-grain weight. The mutant alleles provide novel resources for improvement of wheat plant architecture.

The erect leaf plays a crucial role in determining plant architecture, with its growth and development regulated by genetic factors. However, there has been a lack of comprehensive studies on the regulatory mechanisms governing wheat lamina joint development, thus failing to meet current breeding demands. In this study, a wheat erect leaf mutant, mths29, induced via fast neutron mutagenesis, was utilized for QTL fine mapping and investigation of lamina joint development. Genetic analysis of segregating populations derived from mths29 and Jimai22 revealed that the erect leaf trait was controlled by a dominant single gene. Using BSR sequencing and map-based cloning techniques, the QTL responsible for the erect leaf trait was mapped to a 1.03 Mb physical region on chromosome 5A. Transcriptome analysis highlighted differential expression of genes associated with cell division and proliferation, as well as several crucial transcription factors and kinases implicated in lamina joint development, particularly in the boundary cells of the preligule zone in mths29. These findings establish a solid foundation for understanding lamina joint development and hold promise for potential improvements in wheat plant architecture.