College of Plant Science, Jilin University, Changchun, China.
Zhuhai Branch of State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Zhuhai, China.
Pest Manag Sci. 2022 Dec;78(12):5133-5141. doi: 10.1002/ps.7131. Epub 2022 Sep 7.
Isothiocyanates (ITCs) generated from the 'glucosinolates-myrosinase' defense system in the Brassicaceae exhibit broad antagonistic activity to various fungal pathogens. Nevertheless, the antifungal activity of ITCs to non-adapted fungi of Brassicaceae plants were seldom determined. The inhibitory effects of ITCs on Cochliobolus heterostrophus were evaluated and the antagonistic mechanism was explored.
The mycelium growth of C. heterostrophus was hindered significantly by allyl, 4-(methylthio)-butyl, and phenyethyl ITCs, 4MTB-ITC exhibited the highest inhibitory effect on mycelium growth with an IC value of 53.4 μmol L . In addition, ITCs exhibited obvious inhibitory effect on conidia germination and pathogenicity of C. heterostrophus. Proteomic analysis indicated that the inhibition of C. heterostrophus by A-ITC downregulated the expression of genes related to energy metabolism, oxidoreductase activity, melanin biosynthesis, and cell wall-degrading enzymes. Furthermore, mutants ΔChtrx2 and ΔChnox1 showed increased sensitivity to ITCs, and melanin biosynthesis was inhibited significantly in C. heterostrophus in response to A-ITC. Interestingly, unlike other pathogens that infected Brassicaceae plants, the SaxA in C. heterostrophus displayed no function in ITC degradation. In addition, the ITCs also exhibited obvious inhibitory effect on mycelium growth of Setosphaeria turcica, Fusarium graminearum, and Magnaporthe oryzae.
This study indicated that non-Brassicaceae-adapted pathogens are more sensitive to ITCs, and ITCs could have applications in protecting non-Brassicaceae crops in future. In addition, loss of ChNOX1 and ChTRX2 increased the sensitivity of C. heterostrophus to ITCs. Our results provided potential utilization of ITCs to control diseases caused by non-Brassicaceae pathogenic fungi. © 2022 Society of Chemical Industry.
十字花科植物“硫代葡萄糖苷-黑芥子酶”防御系统产生的异硫氰酸酯（ITC）对各种真菌病原体表现出广泛的拮抗活性。然而，ITC 对十字花科植物非适应性真菌的抗真菌活性很少被确定。评估了 ITC 对 Cochliobolus heterostrophus 的抑制作用，并探讨了其拮抗机制。
烯丙基、4-（甲硫基）-丁基和苯乙基 ITC 显著抑制 C. heterostrophus 的菌丝生长，4MTB-ITC 对菌丝生长的抑制作用最强，IC 值为 53.4 μmol/L。此外，ITC 对 C. heterostrophus 的分生孢子萌发和致病性有明显的抑制作用。蛋白质组学分析表明，A-ITC 抑制 C. heterostrophus 的生长，下调了与能量代谢、氧化还原酶活性、黑色素生物合成和细胞壁降解酶相关的基因表达。此外，突变体ΔChtrx2 和ΔChnox1 对 ITC 表现出更高的敏感性，A-ITC 显著抑制 C. heterostrophus 中黑色素的生物合成。有趣的是，与感染十字花科植物的其他病原体不同，C. heterostrophus 中的 SaxA 没有 ITC 降解功能。此外，ITC 对 Setosphaeria turcica、禾谷镰刀菌和稻瘟病菌的菌丝生长也有明显的抑制作用。
本研究表明，非十字花科适应的病原体对 ITC 更敏感，未来 ITC 可用于保护非十字花科作物。此外，ChNOX1 和 ChTRX2 的缺失增加了 C. heterostrophus 对 ITC 的敏感性。我们的研究结果为利用 ITC 控制非十字花科植物病原真菌引起的疾病提供了潜在的应用价值。© 2022 化学工业协会。
