The tangerine pathotype of A. alternata, which produces a unique host-selective ACT toxin causes brown spots on citrus leaves and fruits. In this study, we report a methionine biosynthesis regulator (MetR), which belong to bZIP transcription factor, is required for methionine metabolism, oxidative stress tolerance and pathogenicity. We generated two ΔAaMetR mutants in the tangerine pathotype of Alternaria alternata and investigated the resulting mutant phenotypes. The ΔAaMetR disruption mutant grew poorly in the absence of methionine and unable to produce conidia. Furthermore, pathogenicity tests have shown that ΔAaMetR mutant on their tangerine host can neither penetrate nor cause disease. These ΔAaMetR mutants exhibit an increased sensitivity to exogenous H₂O₂ and many ROS generating oxidants. To elucidate the transcription network of AaMetR, we performed RNA-Seq experiments on wild-type and ΔAaMetR mutant and identified genes that were differentially expressed between the two genotypes. Transcriptome data demonstrated that AaMetR contributes in many other biological processes including ROS detoxification, sulfur transfer, and amino acid metabolism. Comparative transcriptome analysis indicated that the ΔAaMetR mutant up-regulated several genes involved in cysteine and methionine metabolism. In conclusion, our results highlight the global regulatory role of AaMetR in cysteine and methionine metabolism and provide new insights into the crucial role of ROS detoxification, sporulation and pathogenicity in the tangerine pathotype of A. alternata.

产生独特的宿主选择性ACT毒素的交替链霉菌的橘子型会在柑橘的叶子和果实上引起褐色斑点。在这项研究中，我们报告了甲硫氨酸代谢，氧化应激耐受性和致病性所必需的甲硫氨酸生物合成调节剂（MetR），它属于bZIP转录因子。我们在链格孢菌的橘子型中产生了两个ΔAaMetR突变体，并研究了产生的突变体表型。该ΔAaMetR中断突变体在缺乏蛋氨酸的生长较差，并不能产生分生孢子。此外，致病性测试表明，其橘宿主上的ΔAaMetR突变体既不能穿透也不会引起疾病。这些ΔAaMetR突变体对外源H ₂ O ₂和许多产生ROS的氧化剂表现出更高的敏感性。为了阐明AaMetR的转录网络，我们对野生型和ΔAaMetR突变体进行了RNA-Seq实验，并鉴定了两种基因型之间差异表达的基因。转录组数据表明，AaMetR参与了许多其他生物学过程，包括ROS解毒，硫转移和氨基酸代谢。比较转录组分析表明，ΔAaMetR突变体上调了与半胱氨酸和蛋氨酸代谢有关的几个基因。总之，我们的研究结果突出显示半胱氨酸和蛋氨酸代谢AaMetR的全球监管作用，并提供新的见解ROS解毒，孢子和致病性的的橘致病型的关键作用A.病菌。