Li Chunhong, Wang Kaituo, Lei Changyi, Zou Yanyu, Yang Sisi, Xiang Fei, Li Meilin, Zheng Yonghua
Institute of Fruit Function and Disease Management, Department of Public Health and Management, Chongqing Three Gorges Medical College, Chongqing 404000, P.R. China.
College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095 Jiangsu, P.R. China.
J Exp Bot. 2025 Feb 25;76(4):1202-1229. doi: 10.1093/jxb/erae448.
The inducer β-aminobutyric acid (BABA) participates in the immune response in various plants. However, the specific mitogen-activated protein kinase (MAPK) cascade involved in BABA-induced resistance (BABA-IR) has not yet been elucidated. Here, peach (Prunus persica) fruits treated with the BABA exhibited pattern-triggered immunity defense against Rhizopus stolonifer, accompanied by the generation of reactive oxygen species and activation of a MAPK cascade. Transcriptome sequencing suggested that a total of 15 MAPK kinase kinase (PpMAPKKK)/MAPK kinase (PpMAPKK)/PpMAPK genes were involved in BABA-IR in peach fruit. Further qRT-PCR analysis showed that the transcript profiles of PpMAPKKK3, PpMAPKK5, and PpMAPK1 were elevated. Subsequently, yeast two-hybrid, luciferase complementation imaging, pull-down, and in vitro phosphorylation assays were conducted to characterize the complete MAPK cascade (PpMAPKKK3-PpMAPKK5-PpMAPK1) involved in peach fruit. Moreover, the downstream events of MAPK1 include the involvement of SNARE13 and the corresponding NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1)-responsive defense. Single silencing of MAPKKK3, MAPKK5, or MAPK1 and double silencing of MAPKKK3 and MAPKK5 or MAPKK5 and MAPK1 resulted in enhanced susceptibility to the fungus R. stolonifer in mutants and attenuated salicylic acid (SA)-dependent defense gene expression. In contrast, the homologous or heterologous overexpression of PpSNARE13 in peach fruit or Arabidopsis led to an enhanced SA pool and elevated expression of pathogenesis related (PR) genes. Reciprocally, the ppsnare13cas9 mutants were generally compromised in the priming of SA-dependent resistance. Therefore, the MAPKKK3-MAPKK5-MAPK1 cascade contributed to pattern-triggered immunity signal transduction in BABA-elicited peach fruit, by combination with downstream events such as SNARE13, NPR1, and SA-dependent signaling.
诱导剂β-氨基丁酸（BABA）参与多种植物的免疫反应。然而，尚未阐明参与BABA诱导抗性（BABA-IR）的具体丝裂原活化蛋白激酶（MAPK）级联反应。在此，用BABA处理的桃（Prunus persica）果实对匍枝根霉表现出模式触发免疫防御，伴随着活性氧的产生和MAPK级联反应的激活。转录组测序表明，共有15个MAPK激酶激酶（PpMAPKKK）/MAPK激酶（PpMAPKK）/PpMAPK基因参与桃果实的BABA-IR。进一步的qRT-PCR分析表明，PpMAPKKK3、PpMAPKK5和PpMAPK1的转录谱升高。随后，进行了酵母双杂交、荧光素酶互补成像、下拉和体外磷酸化试验，以表征参与桃果实的完整MAPK级联反应（PpMAPKKK3-PpMAPKK5-PpMAPK1）。此外，MAPK1的下游事件包括SNARE13的参与以及相应的病程相关基因非表达子1（NPR1）响应防御。MAPKKK3、MAPKK5或MAPK1的单基因沉默以及MAPKKK3和MAPKK5或MAPKK5和MAPK1的双基因沉默导致突变体对匍枝根霉的易感性增强，水杨酸（SA）依赖性防御基因表达减弱。相反，PpSNARE13在桃果实或拟南芥中的同源或异源过表达导致SA库增加和病程相关（PR）基因表达升高。相反，ppsnare13cas9突变体在SA依赖性抗性的引发方面普遍受损。因此，MAPKKK3-MAPKK5-MAPK1级联反应通过与SNARE13、NPR1和SA依赖性信号传导等下游事件相结合，促进了BABA诱导的桃果实中模式触发免疫信号转导。
