Yang Fan, Ji Sirong, Bai Lanping, Ke Yan, Lai Weiqiang, Long Chao-An
Henan Provincial Engineering Research Center for Horticultural Plant Resource Utilization and Germplasm Innovation, College of Horticulture and Landscape Architecture, Henan Institute of Science and Technology, Xinxiang 453003, PR China; National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, National R&D Center for Citrus Preservation, National Centre of Citrus Breeding, Huazhong Agricultural University, Wuhan 430070, PR China.
National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, National R&D Center for Citrus Preservation, National Centre of Citrus Breeding, Huazhong Agricultural University, Wuhan 430070, PR China.
Pestic Biochem Physiol. 2025 Sep;213:106480. doi: 10.1016/j.pestbp.2025.106480. Epub 2025 May 27.
Citrus green mold caused by the fungi Penicillium digitatum always brings out enormous economic losses during the postharvest period. In practice, this pathogen is generally controlled by the demethylation inhibitor (DMI) fungicides, but massive usage of DMIs leads to the increasing occurrence of resistant strains and concerns of public safety. Hence, it is vital to clarify the molecular mechanism of P. digitatum response to DMIs. In this study, we investigated the biological function of gene PdRSR1, the Rap1 protein of Ras GTPase family in P. digitatum. First, gene PdRSR1 was deleted and complemented in the principle of homologous recombination, and the deletion mutant ΔPdRSR1 showed highly reduced resistance to DMIs. The phenotypic assay indicated that strain ΔPdRSR1 had severe defects in osmotic stress tolerance and cell wall integrity, but the hyphal growth and pathogenicity were still normal. Compared with wild-type strain N1, the sterol and trehalose levels of strain ΔPdRSR1 were detected to be sharply declined with or without prochloraz-treated. The RT-qPCR analysis suggested that prochloraz did not influence the expression of PdRSR1, but suppressed it of PdRas1 and their activating proteins PdGAPs, which disturbed the transcription of downstream metabolism, including the MAPK signaling pathway, the synthesis of chitin, trehalose and sterol, and the activities of efflux transporters. Taken together, our work characterized that GTPase PdRSR1 is an essential target to prochloraz in P. digitatum, and provided a new insight of P. digitatum to response to prochloraz.
由指状青霉引起的柑橘绿霉病在采后阶段总是造成巨大的经济损失。在实际生产中，这种病原菌通常由脱甲基抑制剂（DMI）类杀菌剂控制，但大量使用DMI类杀菌剂导致抗性菌株的发生率不断增加，并引发了公众安全担忧。因此，阐明指状青霉对DMI类杀菌剂反应的分子机制至关重要。在本研究中，我们调查了指状青霉中Ras GTPase家族的Rap1蛋白基因PdRSR1的生物学功能。首先，按照同源重组原理对基因PdRSR1进行缺失和互补，缺失突变体ΔPdRSR1对DMI类杀菌剂的抗性显著降低。表型分析表明，菌株ΔPdRSR1在渗透胁迫耐受性和细胞壁完整性方面存在严重缺陷，但菌丝生长和致病性仍正常。与野生型菌株N1相比，无论是否用咪鲜胺处理，菌株ΔPdRSR1的甾醇和海藻糖水平均显著下降。RT-qPCR分析表明，咪鲜胺不影响PdRSR1的表达，但抑制了PdRas1及其激活蛋白PdGAPs的表达，从而干扰了下游代谢的转录，包括MAPK信号通路、几丁质、海藻糖和甾醇的合成以及外排转运蛋白的活性。综上所述，我们的工作表明GTPase PdRSR1是指状青霉中咪鲜胺的一个重要作用靶点，并为指状青霉对咪鲜胺的反应提供了新的见解。
