A small GTP-binding host protein is required for entry of powdery mildew fungus into epidermal cells of barley
A small GTP-binding host protein is required for entry of powdery mildew fungus into epidermal cells of barley
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DOI：
10.1104/pp.010805
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发表时间：
2002-04-01
期刊：
影响因子：
7.4
通讯作者：
Hückelhoven, R
中科院分区：
文献类型：
--
作者：
Schultheiss, H;Dechert, C;Hückelhoven, R
小GTP结合蛋白，例如来自RAC家族的那些，是通常参与细胞外刺激的加工的胞质信号转导蛋白。植物RAC蛋白参与调节植物细胞结构、次生壁形成、分生组织信号传导和防御病原体。我们从大麦（Hordeum vulgare）中分离到一个RacB同源物，以研究其在大麦白粉病（Blumeria graminis f.sp. hordei）抗性中的作用。Rac B在大麦表皮中组成型表达，其表达水平不受B接种的强烈影响。禾本科植物然而，在用RacB-双链RNA对大麦叶片段进行生物枪轰击后，序列特异性RNA干扰RacB功能以细胞自主和基因型特异的方式抑制真菌吸器的建立。对B中度易感的突变体损害了Mlo野生型基因和Ror 1基因（基因型mlo 5 ror 1）的功能。RacB特异性RNA干扰对小麦白粉病抗性没有影响。因此，表型，诱导的RacB特异性RNA干扰，显然是依赖于相同的过程作为mlo 5介导的广泛的阻力，这是抑制ror 1。我们的结论是RAC小GTP结合蛋白是成功的真菌吸器建立所必需的，这种功能可能与MLO相关的功能。
Small GTP-binding proteins such as those from the RAC family are cytosolic signal transduction proteins that often are involved in processing of extracellular stimuli. Plant RAC proteins are implicated in regulation of plant cell architecture, secondary wall formation, meristem signaling, and defense against pathogens. We isolated a RacB homolog from barley (Hordeum vulgare) to study its role in resistance to the barley powdery mildew fungus (Blumeria graminis f.sp. hordei). RacB was constitutively expressed in the barley epidermis and its expression level was not strongly influenced by inoculation with B. graminis. However, after biolistic bombardment of barley leaf segments with RacB-double-stranded RNA, sequence-specific RNA interference with RacB function inhibited fungal haustorium establishment in a cell-autonomous and genotype-specific manner. Mutants compromised in function of the Mlo wild-type gene and the Ror1 gene (genotype mlo5 ror1) that are moderately susceptible to B. graminis showed no alteration in powdery mildew resistance upon RacB-specific RNA interference. Thus, the phenotype, induced by RacB-specific RNA interference, was apparently dependent on the same processes as mlo5-mediated broad resistance, which is suppressed by ror1. We conclude that an RAC small GTP-binding protein is required for successful fungal haustorium establishment and that this function may be linked to MLO-associated functions.