二氢乳清酶(DHOase)是内源性嘧啶核苷酸从头生物合成途径六个酶反应步骤中的第三种酶,这是一种在细菌和真核生物中都保守的代谢途径。然而,DHOase在植物病原真菌中的生物学功能研究非常有限。在这项研究中,我们在稻瘟病菌稻瘟病菌中鉴定并命名了酿酒酵母DHOaseUra4的同源蛋白MoPyr4,并研究了其调节真菌生长的能力,致病性,和自噬。删除MoPYR4导致生长缺陷,分生孢子,附睾形成,糖原和脂滴的转移和降解,扩张的积累,以及米曲霉的侵入性菌丝扩增,最终导致真菌致病性减弱。长期补充外源性尿苷-5'-磷酸(UMP)可以有效恢复ΔMopyr4突变体的表型和毒力。进一步研究发现MoPyr4还参与了Pmk1-MAPK信号通路的调控,与过氧化物酶体共定位用于氧化应激反应,参与调节OsM1-MAPK信号通路对高渗应激的反应。此外,MoPyr4与参与自噬的核心蛋白MoAtg5相互作用,并正向调节自噬降解。一起来看,我们的结果表明,用于UMP生物合成的MoPyr4对于米曲霉的发育和致病性至关重要。我们还发现MoPyr4通过参与Pmk1-MAPK信号通路在外界应激反应和致病机制中发挥了重要作用。过氧化物酶体相关氧化应激反应机制,OsM1-MAPK信号通路和自噬通路。
Dihydroorotase (DHOase) is the third enzyme in the six enzymatic reaction steps of the endogenous pyrimidine nucleotide de novo biosynthesis pathway, which is a metabolic pathway conserved in both bacteria and eukaryotes. However, research on the biological function of DHOase in plant pathogenic fungi is very limited. In this study, we identified and named MoPyr4, a homologous protein of Saccharomyces cerevisiae DHOase Ura4, in the rice blast fungus Magnaporthe oryzae and investigated its ability to regulate fungal growth, pathogenicity, and autophagy. Deletion of MoPYR4 led to defects in growth, conidiation, appressorium formation, the transfer and degradation of glycogen and lipid droplets, appressorium turgor accumulation, and invasive hypha expansion in M. oryzae, which eventually resulted in weakened fungal pathogenicity. Long-term replenishment of exogenous uridine-5\'-phosphate (UMP) can effectively restore the phenotype and virulence of the ΔMopyr4 mutant. Further study revealed that MoPyr4 also participated in the regulation of the Pmk1-MAPK signaling pathway, co-localized with
peroxisomes for the oxidative stress response, and was involved in the regulation of the Osm1-MAPK signaling pathway in response to hyperosmotic stress. In addition, MoPyr4 interacted with MoAtg5, the core protein involved in autophagy, and positively regulated autophagic degradation. Taken together, our results suggested that MoPyr4 for UMP biosynthesis was crucial for the development and pathogenicity of M. oryzae. We also revealed that MoPyr4 played an essential role in the external stress response and pathogenic mechanism through participation in the Pmk1-MAPK signaling pathway, peroxisome-related oxidative stress response mechanism, the Osm1-MAPK signaling pathway and the autophagy pathway.