Dong Yifan, An Qi, He Yi, Zhang Yue, Guo Ge, Zhang Changsheng, Zhang Yicong, Xia Xiaobo, Wang Yuhua, Zhang Shiyu, Yang Dong-Lei, Ma Wujun, Whitford Ryan, Yang Xiujuan, Zhang Zhengguang, Li Gang
State Key Laboratory of Agricultural and Forestry Biosecurity, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Zhongshan Biological Breeding Laboratory, CIMMYT-JAAS Joint Center for Wheat Diseases, The Research Center of Wheat Scab, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Plant Cell. 2025 Aug 4;37(8). doi: 10.1093/plcell/koaf177.
Pathogens constantly attack staple crops, leading to substantial yield losses. Plant-pathogen interactions activate endogenous plant-secreted peptides, which act as immunity inducers and are promising breeding targets for enhancing crop resistance to pathogens. However, the identification and mechanisms of immunogenic peptides in staple crops remain largely unexplored. Here, we demonstrated that plant elicitor peptides (TaPeps) in wheat (Triticum aestivum), processed by a metacaspase, are competent to trigger plant immunity and contribute to resistance against Fusarium head blight (FHB). Using exogenous phytocytokine peptide screens, we identified 3 potential TaPeps acting as elicitors that significantly improve FHB resistance. Mechanistically, these elicitors activate innate immune signals and calcium dynamics in response to the Fusarium pathogen via wheat PEP RECEPTOR 1. Overexpression of endogenous PRECURSOR OF PEPs (TaPROPEPs) further reduces FHB severity. Moreover, we characterized the natural form of TaPeps in planta, revealing that the wheat Type-II metacaspase TaMCA-IIa cleaves TaPROPEPs at a conserved arginine residue, promoting TaPep maturation and immune activation. In Tamca-IIa mutants, the efficiency of TaPep maturation was decreased and calcium dynamics were impaired, resulting in FHB susceptibility. Conversely, overexpressing TaMCA-IIa in wheat enhanced the immune response and FHB resistance without causing pleiotropic growth penalties. Our findings highlight TaPeps as potential immune-inducing biologicals for crop protection and uncover the metacaspase-Peps-receptor module in mediating plant disease resistance.
病原体不断侵袭主要农作物，导致产量大幅损失。植物与病原体的相互作用会激活植物内源性分泌肽，这些肽作为免疫诱导剂，是增强作物对病原体抗性的有前景的育种目标。然而，主要农作物中免疫原性肽的鉴定及其作用机制在很大程度上仍未被探索。在此，我们证明了小麦（Triticum aestivum）中的植物激发子肽（TaPeps）经一个 metacaspase 加工后，能够触发植物免疫并有助于抵抗赤霉病（FHB）。通过外源植物细胞因子肽筛选，我们鉴定出 3 种潜在的 TaPeps 作为激发子，可显著提高对 FHB 的抗性。从机制上讲，这些激发子通过小麦 PEP 受体 1 激活先天免疫信号和钙动态变化以应对镰刀菌病原体。内源性 TaPeps 前体（TaPROPEPs）的过表达进一步降低了 FHB 的严重程度。此外，我们对 TaPeps 在植物体内的天然形式进行了表征，发现小麦 II 型 metacaspase TaMCA-IIa 在一个保守的精氨酸残基处切割 TaPROPEPs，促进 TaPep 的成熟和免疫激活。在 Tamca-IIa 突变体中，TaPep 的成熟效率降低，钙动态变化受损，导致对 FHB 易感。相反，在小麦中过表达 TaMCA-IIa 增强了免疫反应和对 FHB 的抗性，且未造成多效性生长缺陷。我们的研究结果突出了 TaPeps 作为潜在的免疫诱导生物制剂用于作物保护，并揭示了 metacaspase - Peps - 受体模块在介导植物抗病性中的作用。
