Zimmerli Laurent, Stein Mónica, Lipka Volker, Schulze-Lefert Paul, Somerville Shauna
Department of Plant Biology, Carnegie Institution of Washington, Stanford, CA 94305, USA.
Plant J. 2004 Dec;40(5):633-46. doi: 10.1111/j.1365-313X.2004.02236.x.
Arabidopsis does not support the growth and asexual reproduction of the barley pathogen, Blumeria graminis f. sp. hordei Bgh). A majority of germlings fail to penetrate the epidermal cell wall and papillae. To gain additional insight into this interaction, we determined whether the salicylic acid (SA) or jasmonate (JA)/ethylene (ET) defence pathways played a role in blocking barley powdery mildew infections. Only the eds1 mutant and NahG transgenics supported a modest increase in penetration success by the barley powdery mildew. We also compared the global gene expression patterns of Arabidopsis inoculated with the non-host barley powdery mildew to those inoculated with a virulent, host powdery mildew, Erysiphe cichoracearum. Genes repressed by inoculations with non-host and host powdery mildews relative to non-inoculated control plants accounted for two-thirds of the differentially expressed genes. A majority of these genes encoded components of photosynthesis and general metabolism. Consistent with this observation, Arabidopsis growth was inhibited following inoculation with Bgh, suggesting a shift in resource allocation from growth to defence. A number of defence-associated genes were induced during both interactions. These genes likely are components of basal defence responses, which do not effectively block host powdery mildew infections. In addition, genes encoding defensins, anti-microbial peptides whose expression is under the control of the JA/ET signalling pathway, were induced exclusively by non-host pathogens. Ectopic activation of JA/ET signalling protected Arabidopsis against two biotrophic host pathogens. Taken together, these data suggest that biotrophic host pathogens must either suppress or fail to elicit the JA/ET signal transduction pathway.
拟南芥不支持大麦病原体大麦白粉菌（Blumeria graminis f. sp. hordei，Bgh）的生长和无性繁殖。大多数芽管无法穿透表皮细胞壁和乳突。为了进一步了解这种相互作用，我们确定水杨酸（SA）或茉莉酸（JA）/乙烯（ET）防御途径是否在阻止大麦白粉病感染中发挥作用。只有eds1突变体和NahG转基因植株支持大麦白粉病穿透成功率有适度增加。我们还比较了接种非寄主大麦白粉病的拟南芥与接种致病力强的寄主白粉病——菊苣白粉菌（Erysiphe cichoracearum）的拟南芥的全基因组表达模式。相对于未接种的对照植株，接种非寄主和寄主白粉病后被抑制的基因占差异表达基因的三分之二。这些基因大多数编码光合作用和一般代谢的成分。与这一观察结果一致，接种Bgh后拟南芥的生长受到抑制，这表明资源分配从生长转向了防御。在这两种相互作用过程中都诱导了一些与防御相关的基因。这些基因可能是基础防御反应的组成部分，不能有效地阻止寄主白粉病的感染。此外，编码防御素（其表达受JA/ET信号通路控制的抗菌肽）的基因仅由非寄主病原体诱导。JA/ET信号的异位激活保护拟南芥免受两种活体营养型寄主病原体的侵害。综上所述，这些数据表明，活体营养型寄主病原体必须抑制或无法激活JA/ET信号转导途径。
