Small EPIDERMAL PATTERNING FACTOR-LIKE2 peptides regulate awn development in rice

Peptide hormones in plants

Peptide hormones are defined as small secreted polypeptide-based intercellular communication signal molecules. Such peptide hormones are encoded by nuclear genes, and often go through proteolytic processing of preproproteins and post-translational modifications. Most peptide hormones are secreted out of the cell to interact with membrane-associated receptors in neighboring cells, and subsequently activate signal transductions, leading to changes in gene expression and cellular responses. Since the discovery of the first plant peptide hormone, systemin, in tomato in 1991, putative peptide hormones have continuously been identified in different plant species, showing their importance in both short- and long-range signal transductions. The roles of peptide hormones are implicated in, but not limited to, processes such as self-incompatibility, pollination, fertilization, embryogenesis, endosperm development, stem cell regulation, plant architecture, tissue differentiation, organogenesis, dehiscence, senescence, plant-pathogen and plant-insect interactions, and stress responses. This article, collectively written by researchers in this field, aims to provide a general overview for the discoveries, functions, chemical natures, transcriptional regulations, and post-translational modifications of peptide hormones in plants. We also updated recent discoveries in receptor kinases underlying the peptide hormone sensing and down-stream signal pathways. Future prospective and challenges will also be discussed at the end of the article.

Genetic dissection of foxtail millet bristles using combined QTL mapping and RNA-seq

KEY MESSAGE

QTL mapping of two RIL populations in multiple environments revealed a consistent QTL for bristle length, and combined with RNA-seq, a potential candidate gene influencing bristle length was identified. Foxtail millet bristles play a vital role in increasing yields and preventing bird damage. However, there is currently limited research on the molecular regulatory mechanisms underlying foxtail millet bristle formation, which constrains the genetic improvement and breeding of new foxtail millet varieties. This study leveraged genetic linkage maps from two populations: the published RYRIL population (Hongjiugu × Yugu 18) with 1420 bins and the newly established YYRIL population (Huangruangu × Yugu 18) with 542 bins. We identified 17 QTLs associated with bristle length, explaining 1.76-47.37% of the phenotypic variation. Among these, 6 were multi-environment QTLs, and 11 were environment-specific QTLs. Notably, qBL-1-1 and qBL-3-2 were detected in both populations, and exhibited epistasis interactions. By analyzing genotypic data from the RYRIL population and its parents, we identified two lines with significant variation in bristle length at the qBL-1-1 locus, designated CM3 (short) and CM4 (long). RNA-seq during the flowering phase identified 1812 differentially expressed genes (DEGs). Thirty-three DEGs were identified within 6 multi-environment QTL regions, and the RNA-seq results were validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Within the qBL-1-1 region, Seita.1G325800 is predicted to be a key candidate gene controlling foxtail millet bristle length. These findings provide preliminary insights into the genetic basis of bristle development and lay a foundation for the genetic improvement of foxtail millet bristle length.

Miniature-inverted-repeat transposable elements contribute to phenotypic variation regulation of rice induced by space environment

Introduction

Rice samples exposed to the space environment have generated diverse phenotypic variations. Miniature-inverted-repeat transposable elements (MITEs), often found adjacent to genes, play a significant role in regulating the plant genome. Herein, the contribution of MITEs in regulating space-mutagenic phenotypes was explored.

Methods

The space-mutagenic phenotype changes in the F3 to F5 generations of three space-mutagenic lines from the rice varieties Dongnong423 (DN423) and Dongnong (DN416) were meticulously traced. Rice leaves samples at the heading stage from three space-mutagenic lines were subjected to high coverage whole-genome bisulfite sequencing and whole-genome sequencing. These analyses were conducted to investigate the effects of MITEs related epigenetic and genetic variations on space-mutagenic phenotypes.

Results and discussion

Studies have indicated that MITEs within gene regulatory regions might contribute to the formation and differentiation of space-mutagenic phenotypes. The space environment has been shown to induce the transposable elements insertion polymorphisms of MITEs (MITEs-TIPs), with a notable preference for insertion near genes involved in stress response and phenotype regulation. The space-induced MITEs-TIPs contributed to the formation of space-mutagenic phenotype by modulating the expression of gene near the insertion site. This study underscored the pivotal role of MITEs in modulating plant phenotypic variation induced by the space environment, as well as the transgenerational stability of these phenotypic variants.

Competitive binding of small antagonistic peptides to the OsER1 receptor optimizes rice panicle architecture

Rice panicle architecture is a pivotal trait that strongly contributes to grain yield. Small peptide ligands from the OsEPF/EPFL family synergistically control panicle architecture by recognition of the OsER1 receptor and subsequent activation of the OsMKKK10-OsMKK4-OsMPK6 cascade, indicating that specific ligand-receptor pairs orchestrate rice panicle development. However, how small homologous peptides fine-tune organ morphogenesis by targeting a common receptor remains to be clarified. Here, we report that the small peptide OsEPFL5 acts as a ligand of the OsER1 receptor that inactivates the OsMKKK10-OsMKK4-OsMPK6 cascade, suggesting that OsEPFL5 plays a role opposite to that of the OsEPFL6/7/8/9 subfamily in regulating spikelet number per panicle and grain size. Notably, OsEPFL5 competitively replaces binding of OsEPFL6, OsEPFL7, OsEPFL8, or OsEPFL9 to the OsER1 receptor, revealing antagonistic competition between these small homologous peptides. Specifically enhancing the expression of OsEPFL5 can significantly improve grain yield by suppressing functions of the ligand-receptor pairs OsEPFL6-OsER1, OsEPFL7-OsER1, OsEPFL8-OsER1, and OsEPFL9-OsER1, suggesting that competitive binding to the OsER1 receptor by small antagonistic peptides can optimize rice panicle architecture. Our findings clarify how a receptor agonist and antagonist define inductive and inhibitory cues to shape rice panicle architecture, thus providing a new method for rationally breaking yield-trait coupling by manipulating small antagonistic peptides.

Imaging the spatial distribution of structurally diverse plant hormones

Plant hormones are essential and structurally diverse molecules that regulate various aspects of plant growth, development, and stress responses. However, the precise analysis of plant hormones in complex biological samples poses a challenge due to their low concentrations, dynamic levels, and intricate spatial distribution. Moreover, the complexity and interconnectedness of hormone signaling networks make it difficult to simultaneously trace multiple hormone spatial distributions. In this review, we provide an overview of currently recognized small-molecule plant hormones, signal peptide hormones, and plant growth regulators, along with the analytical methods employed for their analysis. We delve into the latest advancements in mass spectrometry imaging and in situ fluorescence techniques, which enable the examination of the spatial distribution of plant hormones. The advantages and disadvantages of these imaging techniques are further discussed. Finally, we propose potential avenues in imaging techniques to further enhance our understanding of plant hormone biology.

Grass awns: Morphological diversity arising from developmental constraint

Grasses dominate agriculturally and ecologically. One hypothesized driver of this dominance is grasses' facility for grain dispersal and rapid seedling establishment. Dispersal and establishment are aided by the awned lemma - a modified bract associated with grass flowers. Awns have diverse forms, many proposed functions, and have been gained and lost repeatedly in grass evolution. Here we hypothesize that the evolution of awn emergence is underpinned by deep conservation of developmental genes. Awns are likely homologous to leaf blades. Because leaf blades are essential, every grass species likely has a latent developmental program available for awn development. This developmental program may be repeatedly reactivated in lemmas, resulting in the frequent appearance of awns. Because awns are inessential, they can be lost and modified without dire consequences to fitness, resulting in the frequent loss and diversity of awns. Replicated awn evolution reveals how developmental conservation can potentiate the evolution of diversity. Awns also present a powerful opportunity to dissect mechanisms of leaf development.

Small peptides: novel targets for modulating plant-rhizosphere microbe interactions

The crucial role of rhizosphere microbes in plant growth and their resilience to environmental stresses underscores the intricate communication between microbes and plants. Plants are equipped with a diverse set of signaling molecules that facilitate communication across different biological kingdoms, although our comprehension of these mechanisms is still evolving. Small peptides produced by plants (SPPs) and microbes (SPMs) play a pivotal role in intracellular signaling and are essential in orchestrating various plant development stages. In this review, we posit that SPPs and SPMs serve as crucial signaling agents for the bidirectional cross-kingdom communication between plants and rhizosphere microbes. We explore several potential mechanistic pathways through which this communication occurs. Additionally, we propose that leveraging small peptides, inspired by plant-rhizosphere microbe interactions, represents an innovative approach in the field of holobiont engineering.

Pull the fuzes: Processing protein precursors to generate apoplastic danger signals for triggering plant immunity

The apoplast is one of the first cellular compartments outside the plasma membrane encountered by phytopathogenic microbes in the early stages of plant tissue invasion. Plants have developed sophisticated surveillance mechanisms to sense danger events at the cell surface and promptly activate immunity. However, a fine tuning of the activation of immune pathways is necessary to mount a robust and effective defense response. Several endogenous proteins and enzymes are synthesized as inactive precursors, and their post-translational processing has emerged as a critical mechanism for triggering alarms in the apoplast. In this review, we focus on the precursors of phytocytokines, cell wall remodeling enzymes, and proteases. The physiological events that convert inactive precursors into immunomodulatory active peptides or enzymes are described. This review also explores the functional synergies among phytocytokines, cell wall damage-associated molecular patterns, and remodeling, highlighting their roles in boosting extracellular immunity and reinforcing defenses against pests.

Genome-wide identification and expression analysis of EPF/EPFL gene family in Populus trichocarpa

The Epidermal Patterning Factor/EPF-like (EPF/EPFL) family encodes a specific type of secreted protein in plants and plays an important role in plant growth and development, especially in the process of morphogenesis. To investigate the characteristics of EPF/EPFL gene family members and their regulatory functions in stomatal development of Populus trichocarpa, a total of 15 EPF/EPFL family genes were identified. Then the gene structure, chromosome location, phylogenetic relationship, protein conserved domain and gene expression profile were analyzed. According to phylogenetic analysis, PtEPF/EPFL can be classified into four groups. The gene structure and protein conservation motifs within the EPF family indicate the high conservation of the PtEPF/EPFL sequence. The promoter region of PtEPF/EPFL was found to contain cis-elements in response to stress and plant hormones. In addition, RT-qPCR results indicated that the PtEPF/EPFL have a differentially expressed in different tissues. Under drought stress treatment, a substantial upregulation was observed in the majority of PtEPF/EPFL members, suggesting their potential involvement in drought response. These results provide a theoretical basis for future exploration of the characteristics and functions of more PtEPF/EPFL genes.

TabHLH27 orchestrates root growth and drought tolerance to enhance water use efficiency in wheat

Cultivating high-yield wheat under limited water resources is crucial for sustainable agriculture in semiarid regions. Amid water scarcity, plants activate drought response signaling, yet the delicate balance between drought tolerance and development remains unclear. Through genome-wide association studies and transcriptome profiling, we identified a wheat atypical basic helix-loop-helix (bHLH) transcription factor (TF), TabHLH27-A1, as a promising quantitative trait locus candidate for both relative root dry weight and spikelet number per spike in wheat. TabHLH27-A1/B1/D1 knock-out reduced wheat drought tolerance, yield, and water use efficiency (WUE). TabHLH27-A1 exhibited rapid induction with polyethylene glycol (PEG) treatment, gradually declining over days. It activated stress response genes such as TaCBL8-B1 and TaCPI2-A1 while inhibiting root growth genes like TaSH15-B1 and TaWRKY70-B1 under short-term PEG stimulus. The distinct transcriptional regulation of TabHLH27-A1 involved diverse interacting factors such as TaABI3-D1 and TabZIP62-D1. Natural variations of TabHLH27-A1 influence its transcriptional responses to drought stress, with TabHLH27-A1Hap-II associated with stronger drought tolerance, larger root system, more spikelets, and higher WUE in wheat. Significantly, the excellent TabHLH27-A1Hap-II was selected during the breeding process in China, and introgression of TabHLH27-A1Hap-II allele improved drought tolerance and grain yield, especially under water-limited conditions. Our study highlights TabHLH27-A1's role in balancing root growth and drought tolerance, providing a genetic manipulation locus for enhancing WUE in wheat.

Investigation on the Potential Functions of ZmEPF/EPFL Family Members in Response to Abiotic Stress in Maize

Maize is an important crop used for food, feed, and fuel. Abiotic stress is an important factor affecting maize yield. The EPF/EPFL gene family encodes class-specific secretory proteins that play an important role in the response to abiotic stress in plants. In order to explore and utilize the EPF/EPFL family in maize, the family members were systematically identified, and their chromosomal localization, physicochemical properties, cis-acting element prediction in promoters, phylogenetic tree construction, and expression pattern analysis were carried out using bioinformatics techniques. A total of 18 ZmEPF/EPFL proteins were identified in maize, which are mostly alkaline and a small portion acidic. Subcellular localization results showed that ZmEPF6, ZmEPF12, and ZmEPFL2 are localized in the nucleus and cytoplasm. Analysis of cis-acting elements revealed that members of the ZmEPF/EPFL family contain regulatory elements such as light response, anoxic, low temperature, and hormone response regulatory elements. RT-qPCR results showed that these family members are indeed responding to cold stress and hormone treatments. These results of this study provide a theoretical basis for improving the abiotic stress resistance of maize in future research.

Genome-wide analyses of member identification, expression pattern, and protein-protein interaction of EPF/EPFL gene family in Gossypium

BACKGROUND

Epidermal patterning factor / -like (EPF/EPFL) gene family encodes a class of cysteine-rich secretory peptides, which are widelyfound in terrestrial plants.Multiple studies has indicated that EPF/EPFLs might play significant roles in coordinating plant development and growth, especially as the morphogenesis processes of stoma, awn, stamen, and fruit skin. However, few research on EPF/EPFL gene family was reported in Gossypium.

RESULTS

We separately identified 20 G. raimondii, 24 G. arboreum, 44 G. hirsutum, and 44 G. barbadense EPF/EPFL genes in the 4 representative cotton species, which were divided into four clades together with 11 Arabidopsis thaliana, 13 Oryza sativa, and 17 Selaginella moellendorffii ones based on their evolutionary relationships. The similar gene structure and common motifs indicated the high conservation among the EPF/EPFL members, while the uneven distribution in chromosomes implied the variability during the long-term evolutionary process. Hundreds of collinearity relationships were identified from the pairwise comparisons of intraspecifc and interspecific genomes, which illustrated gene duplication might contribute to the expansion of cotton EPF/EPFL gene family. A total of 15 kinds of cis-regulatory elements were predicted in the promoter regions, and divided into three major categories relevant to the biological processes of development and growth, plant hormone response, and abiotic stress response. Having performing the expression pattern analyses with the basic of the published RNA-seq data, we found most of GhEPF/EPFL and GbEPF/EPFL genes presented the relatively low expression levels among the 9 tissues or organs, while showed more dramatically different responses to high/low temperature and salt or drought stresses. Combined with transcriptome data of developing ovules and fibers and quantitative Real-time PCR results (qRT-PCR) of 15 highly expressed GhEPF/EPFL genes, it could be deduced that the cotton EPF/EPFL genes were closely related with fiber development. Additionally, the networks of protein-protein interacting among EPF/EPFLs concentrated on the cores of GhEPF1 and GhEPF7, and thosefunctional enrichment analyses indicated that most of EPF/EPFLs participate in the GO (Gene Ontology) terms of stomatal development and plant epidermis development, and the KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways of DNA or base excision repair.

CONCLUSION

Totally, 132 EPF/EPFL genes were identified for the first time in cotton, whose bioinformatic analyses of cis-regulatory elements and expression patterns combined with qRT-PCR experiments to prove the potential functions in the biological processes of plant growth and responding to abiotic stresses, specifically in the fiber development. These results not only provide comprehensive and valuable information for cotton EPF/EPFL gene family, but also lay solid foundation for screening candidate EPF/EPFL genes in further cotton breeding.

Genome wide association studies on seven yield-related traits of 183 rice varieties in Bangladesh

Rice genetic diversity is regulated by multiple genes and is largely dependent on various environmental factors. Uncovering the genetic variations associated with the diversity in rice populations is the key to breed stable and high yielding rice varieties. We performed genome wide association studies (GWASs) on seven rice yielding traits (grain length, grain width, grain weight, panicle length, leaf length, leaf width, and leaf angle) based on a population of 183 rice landraces of Bangladesh. Our GWASs reveal various chromosomal regions and candidate genes that are associated with different traits in Bangladeshi rice varieties. Noteworthy was the recurrent implication of chromosome 10 in all three grain-shape-related traits (grain length, grain width, and grain weight), indicating its pivotal role in shaping rice grain morphology. Our study also underscores the involvement of transposon gene families across these three traits. For leaf related traits, chromosome 10 was found to harbor regions that are significantly associated with leaf length and leaf width. The results of these association studies support previous findings as well as provide additional insights into the genetic diversity of rice. This is the first known GWAS study on various yield-related traits in the varieties of Oryza sativa available in Bangladesh-the fourth largest rice-producing country. We believe this study will accelerate rice genetics research and breeding stable high-yielding rice in Bangladesh.

Genome-wide identification and phylogenetic and expression pattern analyses of EPF/EPFL family genes in the Rye (Secale cereale L.)

Rye (Secale cereale L.) is one of the major cereal crop species in the Triticeae family and is known to be most tolerant to diverse abiotic stresses, such as cold, heat, osmotic, and salt stress. The EPIDERMAL PATTERNING FACTOR (EPF) and EPF-LIKE (EPFL) families of small secreted peptides act to regulate many aspects of plant growth and development; however, their functions are not widely characterized in rye. In this study, we identified 12 ScEPF/EPFL genes, which can be divided into six groups and are evenly distributed on six rye chromosomes. Further examination of the gene structure and protein conservation motifs of EPF/EPFL family members demonstrated the high conservation of the ScEPF/EPFL sequence. Interactions between ScEPF/EPFL proteins and promoters containing hormone- and stress-responsive cis-acting elements suggest that the regulation of ScEPF/EPFL expression is complex. Expression profiling analyses revealed that ScEPF/EPFL genes exhibited tissue-specific expression patterns. Notably, ScEPFL1,ScEPFL7, ScEPFL9, and ScEPFL10 displayed significantly higher expression levels in spikelets compared to other tissues. Moreover, fluorescence quantification experiments demonstrated that these genes exhibited distinct expression patterns in response to various stress conditions, suggesting that each gene plays a unique role in stress signaling pathways. Our research findings provide a solid basis for further investigation into the functions of ScEPF/EPFLs. Furthermore, these genes can serve as potential candidates for breeding stress-resistant rye varieties and improving production yields.

Redefining awn development in rice through the breeding history of Japanese awn reduction

The study challenges the conventional understanding of awn loss as a domestication syndrome, showing instead that many awned varieties continued to be widely grown in Japan until the early twentieth century and that selection for awn reduction was active at that time, demonstrating that awn loss is not a domestication syndrome but "a trait that emerged during crop improvement". Although selection for awnless mutants was carried out independently using different types of awned cultivars in the early twentieth century in Japan, awn loss was caused by the mutation in OsEPFL1. This suggests that a single mutant haplotype of OsEPFL1 was conserved in the genomes of different cultivars and subsequently selected within each line to meet the demand for awnless varieties. The study also conducts phylogenetic analyses of EPFL1 in 48 grass plants, revealing its unique involvement in awn formation in rice while potentially playing a different role in the domestication of other grass plants. Finally, an attempt is made to isolate an awn-forming gene that has not been identified from the awned rice cultivar "Omachi", which is still cultivated in Japan. The results presented in this paper provide a new perspective on domestication against the conventional understanding of awn development, shedding light on its potential as a useful organ for breeding to mitigate environmental stress.

Blocking of awn development-related gene OsGAD1 coordinately boosts yield and quality of Kam Sweet Rice

Kam Sweet Rice is a high-quality local variety of Guizhou province in China, but most varieties have awns on lemma. In this study, we aimed to obtain awnless varieties of Kam Sweet Rice by blocking the awn development-related gene OsGAD1 using CRISPR/Cas9 technology. We determined that natural variations of the OsGAD1 triggered different lengths of awns of Kam Sweet Rice. We found that the awning rate of the CRISPR lines of OsGAD1 in Guxiangnuo, Goujingao and Gouhuanggang decreased by over 65%, and the number of grains per panicle and yield per plant increased by more than 17% and 20% compared to the wild-types. Furthermore, we indicated that blocking OsGAD1 resulted in an increase of over 2% in the brown rice rate and milled rice rate in these varieties. In addition, the analysis of the transcriptome revealed that the regulation of awn development and yield formation in CRISPR lines of OsGAD1 may involve genes associated with phytohormone and nitrogen pathways. These results suggest that blocking OsGAD1 in Kam Sweet Rice using CRISPR/Cas9 technology can be used for breeding programs seeking high yield and grain quality of Kam Sweet Rice.

MADS1-regulated lemma and awn development benefits barley yield

Floral organ shape and size in cereal crops can affect grain size and yield, so genes that regulate their development are promising breeding targets. The lemma, which protects inner floral organs, can physically constrain grain growth; while the awn, a needle-like extension of the lemma, creates photosynthate to developing grain. Although several genes and modules controlling grain size and awn/lemma growth in rice have been characterized, these processes, and the relationships between them, are not well understood for barley and wheat. Here, we demonstrate that the barley E-class gene HvMADS1 positively regulates awn length and lemma width, affecting grain size and weight. Cytological data indicates that HvMADS1 promotes awn and lemma growth by promoting cell proliferation, while multi-omics data reveals that HvMADS1 target genes are associated with cell cycle, phytohormone signaling, and developmental processes. We define two potential targets of HvMADS1 regulation, HvSHI and HvDL, whose knockout mutants mimic awn and/or lemma phenotypes of mads1 mutants. Additionally, we demonstrate that HvMADS1 interacts with APETALA2 (A-class) to synergistically activate downstream genes in awn/lemma development in barley. Notably, we find that MADS1 function remains conserved in wheat, promoting cell proliferation to increase awn length. These findings extend our understanding of MADS1 function in floral organ development and provide insights for Triticeae crop improvement strategies.

Shining in the dark: the big world of small peptides in plants

Small peptides represent a subset of dark matter in plant proteomes. Through differential expression patterns and modes of action, small peptides act as important regulators of plant growth and development. Over the past 20 years, many small peptides have been identified due to technical advances in genome sequencing, bioinformatics, and chemical biology. In this article, we summarize the classification of plant small peptides and experimental strategies used to identify them as well as their potential use in agronomic breeding. We review the biological functions and molecular mechanisms of small peptides in plants, discuss current problems in small peptide research and highlight future research directions in this field. Our review provides crucial insight into small peptides in plants and will contribute to a better understanding of their potential roles in biotechnology and agriculture.

Optimization of rice panicle architecture by specifically suppressing ligand-receptor pairs

Rice panicle architecture determines the grain number per panicle and therefore impacts grain yield. The OsER1-OsMKKK10-OsMKK4-OsMPK6 pathway shapes panicle architecture by regulating cytokinin metabolism. However, the specific upstream ligands perceived by the OsER1 receptor are unknown. Here, we report that the EPIDERMAL PATTERNING FACTOR (EPF)/EPF-LIKE (EPFL) small secreted peptide family members OsEPFL6, OsEPFL7, OsEPFL8, and OsEPFL9 synergistically contribute to rice panicle morphogenesis by recognizing the OsER1 receptor and activating the mitogen-activated protein kinase cascade. Notably, OsEPFL6, OsEPFL7, OsEPFL8, and OsEPFL9 negatively regulate spikelet number per panicle, but OsEPFL8 also controls rice spikelet fertility. A osepfl6 osepfl7 osepfl9 triple mutant had significantly enhanced grain yield without affecting spikelet fertility, suggesting that specifically suppressing the OsEPFL6-OsER1, OsEPFL7-OsER1, and OsEPFL9-OsER1 ligand-receptor pairs can optimize rice panicle architecture. These findings provide a framework for fundamental understanding of the role of ligand-receptor signaling in rice panicle development and demonstrate a potential method to overcome the trade-off between spikelet number and fertility.

The TaTCP4/10-B1 cascade regulates awn elongation in wheat (Triticum aestivum L.)

Awns are important morphological markers for wheat and exert a strong physiological effect on wheat yield. The awn elongation suppressor B1 has recently been cloned through association and linkage analysis in wheat. However, the mechanism of awn inhibition centered around B1 remains to be clarified. Here, we identified an allelic variant in the coding region of B1 through analysis of re-sequencing data; this variant causes an amino acid substitution and premature termination, resulting in a long-awn phenotype. Transcriptome analysis indicated that B1 inhibited awn elongation by impeding cytokinin- and auxin-promoted cell division. Moreover, B1 directly repressed the expression of TaRAE2 and TaLks2, whose orthologs have been reported to promote awn development in rice or barley. More importantly, we found that TaTCP4 and TaTCP10 synergistically inhibited the expression of B1, and a G-to-A mutation in the B1 promoter attenuated its inhibition by TaTCP4/10. Taken together, our results reveal novel mechanisms of awn development and provide genetic resources for trait improvement in wheat.