RAS2 regulates growth and pathogenesis in Fusarium graminearum
RAS2 regulates growth and pathogenesis in Fusarium graminearum
复制标题
DOI：
10.1094/mpmi-20-6-0627
复制
发表时间：
2007-06-01
影响因子：
3.5
通讯作者：
Dunkle, L. D.
中科院分区：
文献类型：
--
作者：
Bluhm, B. H.;Zhao, X.;Dunkle, L. D.
禾谷镰刀菌（Fusarium graminearum）是禾谷类作物（包括小麦、大麦和玉米）的普遍存在的病原体。由F.禾谷镰刀菌是特别令人关注的，因为收获的谷物经常被有害的真菌毒素如脱氧雪腐镰刀菌烯醇（DON）污染。本研究旨在探讨Ras GTP酶在胃癌发病机制中的作用。F.禾谷镰刀菌含有两个推定的Ras GTP酶编码基因。这两个基因（RAS1和RAS2）表现出不同的模式下，不同的营养条件下的可用性和各种突变体背景的表达。RAS2的存活率很低，但当被破坏时，会引起各种形态缺陷，包括在固体培养基上生长较慢，孢子萌发延迟，以及对小麦穗和玉米穗丝的毒力显著降低。细胞内cAMP水平不受RAS2缺失的影响，并且用cAMP对ras2突变体进行外源性处理不影响表型异常，从而表明RAS2在cAMP信号传导中起次要作用或不起作用。然而，磷酸化的促分裂原活化蛋白（MAP）激酶Gpmk1和表达的分泌脂肪酶（FGL 1）感染所需的ras2突变体显着减少。基于这些观察，我们假设RAS2调节F. Gpmk1 MAP激酶通路的调控。
Fusarium graminearum is a ubiquitous pathogen of cereal crops, including wheat, barley, and maize. Diseases caused by F. graminearum are of particular concern because harvested grains frequently are contaminated with harmful mycotoxins such as deoxynivalenol (DON). In this study, we explored the role of Ras GTPases in pathogenesis. The genome of F. graminearum contains two putative Ras GTPase-encoding genes. The two genes (RAS1 and RAS2) showed different patterns of expression under different conditions of nutrient availability and in various mutant backgrounds. RAS2 was dispensable for survival but, when disrupted, caused a variety of morphological defects, including slower growth on solid media, delayed spore germination, and significant reductions in virulence on wheat heads and maize silks. Intracellular cAMP levels were not affected by deletion of RAS2 and exogenous treatment of the ras2 mutant with cAMP did not affect phenotypic abnormalities, thus indicating that RAS2 plays a minor or no role in cAMP signaling. However, phosphorylation of the mitogen-activated protein (MAP) kinase Gpmk1 and expression of a secreted lipase (FGL1) required for infection were reduced significantly in the ras2 mutant. Based on these observations, we hypothesize that RAS2 regulates growth and virulence in F. graminearum by regulating the Gpmk1 MAP kinase pathway.