Barda Omer, Maor Uriel, Sadhasivam Sudharsan, Bi Yang, Zakin Varda, Prusky Dov, Sionov Edward
Institute of Postharvest and Food Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel.
Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
Front Microbiol. 2020 Feb 13;11:210. doi: 10.3389/fmicb.2020.00210. eCollection 2020.
Pathogenic fungi must respond effectively to changes in environmental pH for successful host colonization, virulence and toxin production. is a mycotoxigenic pathogen with the ability to colonize many plant hosts and secrete ochratoxin A (OTA). In this study, we characterized the functions and addressed the role of PacC-mediated pH signaling in pathogenicity using designed gene knockout mutant. Δ mutant displayed an acidity-mimicking phenotype, which resulted in impaired fungal growth at neutral/alkaline pH, accompanied by reduced sporulation and conidial germination compared to the wild type (WT) strain. The Δ mutant was unable to efficiently acidify the growth media as a direct result of diminished gluconic and citric acid production. Furthermore, loss of resulted in a complete inhibition of OTA production at pH 7.0. Additionally, Δ mutant exhibited attenuated virulence compared to the WT toward grapes and nectarine fruits. Reintroduction of gene into Δ mutant restored the WT phenotype. Our results demonstrate important roles of PacC of in OTA biosynthesis and in pathogenicity by controlling transcription of genes important for fungal secondary metabolism and infection.
致病真菌必须有效地应对环境pH值的变化，才能成功地定殖于宿主、产生毒力和毒素。是一种产真菌毒素的病原体，能够定殖于多种植物宿主并分泌赭曲霉毒素A（OTA）。在本研究中，我们利用设计的基因敲除突变体，对PacC介导的pH信号在致病性中的功能进行了表征，并探讨了其作用。Δ突变体表现出模拟酸性的表型，导致在中性/碱性pH条件下真菌生长受损，与野生型（WT）菌株相比，孢子形成和分生孢子萌发减少。Δ突变体由于葡萄糖酸和柠檬酸产量减少，无法有效地酸化生长培养基。此外，缺失导致在pH 7.0时OTA产生完全受到抑制。此外，与WT相比，Δ突变体对葡萄和油桃果实的毒力减弱。将基因重新导入Δ突变体可恢复WT表型。我们的结果表明，通过控制对真菌次生代谢和感染重要的基因的转录，的PacC在OTA生物合成和致病性中发挥重要作用。
