Peroxisomal carnitine acetyl transferase is required for elaboration of penetration hyphae during plant infection by Magnaporthe grisea
Peroxisomal carnitine acetyl transferase is required for elaboration of penetration hyphae during plant infection by Magnaporthe grisea
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DOI：
10.1111/j.1365-2958.2006.05209.x
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发表时间：
2006-07-01
影响因子：
3.6
通讯作者：
Talbot, Nicholas J.
中科院分区：
文献类型：
--
作者：
Bhambra, Gurpreet K.;Wang, Zheng-Yi;Talbot, Nicholas J.
稻瘟病的致病因子稻瘟病病菌（Magnaporthe grisea）侵入植物组织是由于一种叫做附着胞的特殊感染结构的作用，附着胞被用来破坏叶片角质层，使细胞内的感染性菌丝发育。在本报告中，我们证明了过氧化物酶体肉碱乙酰转移酶（CAT）的活性对附着胞功能，特别是对初级渗透菌丝的发育是必要的。稻瘟病菌的主要CAT活性由PTH2基因编码，该基因在醋酸盐和脂质作用下表达升高，并受环AMP反应通路调控。此外，Pth2-GFP融合蛋白与过氧化物酶体标记蛋白共定位。靶向删除PTH2，产生完全无致病性的突变体，缺乏CAT活性，不能利用一系列脂质底物。Delta pth2附着胞功能的损害与胚管向发育中的感染细胞的脂质储备动员延迟以及感染结构中几丁质分布异常有关。在δ pth2突变体中添加葡萄糖部分恢复了引起稻瘟病和脂质储备动员的能力。综上所述，我们的研究结果提供了证据，证明Pth2在宿主感染过程中产生附着胞功能和渗透菌丝快速发育所必需的乙酰辅酶a池中发挥作用。
Magnaporthe grisea, the causal agent of rice blast disease, invades plant tissue due to the action of specialized infection structures called appressoria, which are used to breach the leaf cuticle and allow development of intracellular, infectious hyphae. In this report we demonstrate that peroxisomal carnitine acetyl transferase (CAT) activity is necessary for appressorium function, and in particular, for the elaboration of primary penetration hyphae. The major CAT activity in M. grisea is encoded by the PTH2 gene, which shows elevated expression in response to acetate and lipid, and is regulated by the cyclic AMP response pathway. Furthermore, a Pth2-GFP fusion protein colocalizes with a peroxisomal marker protein. Targeted deletion of PTH2, generated mutants that were completely non-pathogenic, lacked CAT activity and were unable to utilize a range of lipid substrates. The impairment of appressorium function in Delta pth2 was associated with a delay in lipid reserve mobilization from germ tubes into developing infection cells, and abnormal chitin distribution in infection structures. Addition of glucose to Delta pth2 mutants partially restored the ability to cause rice blast disease and lipid reserve mobilization. Taken together, our findings provide evidence that Pth2 plays a role in the generation of acetyl CoA pools necessary for appressorium function and rapid elaboration of penetration hyphae during host infection.