College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
PLoS One. 2012;7(5):e38324. doi: 10.1371/journal.pone.0038324. Epub 2012 May 31.
Arginine methylation of non-histone proteins by protein arginine methyltransferase (PRMT) has been shown to be important for various biological processes from yeast to human. Although PRMT genes are well conserved in fungi, none of them have been functionally characterized in plant pathogenic ascomycetes. In this study, we identified and characterized all of the four predicted PRMT genes in Fusarium graminearum, the causal agent of Fusarium head blight of wheat and barley. Whereas deletion of the other three PRMT genes had no obvious phenotypes, the Δamt1 mutant had pleiotropic defects. AMT1 is a predicted type I PRMT gene that is orthologous to HMT1 in Saccharomyces cerevisiae. The Δamt1 mutant was slightly reduced in vegetative growth but normal in asexual and sexual reproduction. It had increased sensitivities to oxidative and membrane stresses. DON mycotoxin production and virulence on flowering wheat heads also were reduced in the Δamt1 mutant. The introduction of the wild-type AMT1 allele fully complemented the defects of the Δamt1 mutant and Amt1-GFP fusion proteins mainly localized to the nucleus. Hrp1 and Nab2 are two hnRNPs in yeast that are methylated by Hmt1 for nuclear export. In F. graminearum, AMT1 is required for the nuclear export of FgHrp1 but not FgNab2, indicating that yeast and F. graminearum differ in the methylation and nucleo-cytoplasmic transport of hnRNP components. Because AMT2 also is a predicted type I PRMT with limited homology to yeast HMT1, we generated the Δamt1 Δamt2 double mutants. The Δamt1 single and Δamt1 Δamt2 double mutants had similar defects in all the phenotypes assayed, including reduced vegetative growth and virulence. Overall, data from this systematic analysis of PRMT genes suggest that AMT1, like its ortholog in yeast, is the predominant PRMT gene in F. graminearum and plays a role in hyphal growth, stress responses, and plant infection.
精氨酸甲基化的非组蛋白蛋白质的蛋白质精氨酸甲基转移酶（PRMT）已被证明是重要的各种生物过程从酵母到人。虽然 PRMT 基因在真菌中很好地保守，但在植物病原有丝分裂真菌中，没有一个基因被功能表征。在这项研究中，我们鉴定并表征了在小麦赤霉病和大麦赤霉病病原菌禾谷镰刀菌中所有四个预测的 PRMT 基因。虽然删除其他三个 PRMT 基因没有明显的表型，但Δamt1 突变体表现出多种缺陷。AMT1 是一个预测的 I 型 PRMT 基因，与酿酒酵母中的 HMT1 同源。Δamt1 突变体在营养生长中略有减少，但在无性和有性繁殖中正常。它对氧化和膜应激的敏感性增加。DON 真菌毒素的产生和在开花小麦穗上的毒力也在Δamt1 突变体中降低。野生型 AMT1 等位基因的引入完全弥补了Δamt1 突变体的缺陷，Amt1-GFP 融合蛋白主要定位于细胞核。Hrp1 和 Nab2 是酿酒酵母中的两个 hnRNPs，它们被 Hmt1 甲基化以进行核输出。在禾谷镰刀菌中，AMT1 是 FgHrp1 的核输出所必需的，但不是 FgNab2，这表明酵母和禾谷镰刀菌在 hnRNP 成分的甲基化和核质转运方面存在差异。因为 AMT2 也是一个预测的 I 型 PRMT，与酵母 HMT1 有有限的同源性，所以我们生成了Δamt1Δamt2 双突变体。在所有测定的表型中，Δamt1 单突变体和Δamt1Δamt2 双突变体的表型缺陷相似，包括营养生长和毒力降低。总的来说，对 PRMT 基因的系统分析数据表明，AMT1 与其在酵母中的同源物相似，是禾谷镰刀菌中的主要 PRMT 基因，在菌丝生长、应激反应和植物感染中发挥作用。
