Threonine synthase CoTHR4 is involved in infection-related morphogenesis during the pre-penetration stage in Colletotrichum orbiculare
Threonine synthase CoTHR4 is involved in infection-related morphogenesis during the pre-penetration stage in Colletotrichum orbiculare
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DOI：
10.1016/j.micpath.2019.103746
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发表时间：
2019-12-01
影响因子：
3.8
通讯作者：
Okuno, Tetsuro
中科院分区：
文献类型：
--
作者：
Harata, Ken;Okuno, Tetsuro
葫芦科炭疽病病原菌Colletotrichum orbiculare在识别寄主植物后，启动形态分化，包括分生孢子萌发和角质层附着胞的形成。研究了C.圆叶葫芦需要大量的营养和能量，但葫芦科寄主的表面几乎不富营养。因此，C. Orbiculare必须严格管理其细胞内营养物，以适当诱导感染相关的形态发生。在此，我们利用农杆菌介导的转化技术进行了大规模的插入突变筛选，以鉴定与致病性相关的新基因。Orbiculare的研究，并发现CoTHR 4编码的苏氨酸合酶（Saccharomycescerevisiae THR 4的同系物）是C.圆形的补充苏氨酸使cothr4突变体产生的分生孢子的水平相当于野生型。从苏氨酸处理的cothr4突变体产生的分生孢子未能在苏氨酸的情况下发芽，但保留的能力发芽，并在苏氨酸的存在下形成附着胞。然而，从苏氨酸处理的cothr4突变体产生的分生孢子仍然减弱黄瓜子叶上的致病性，即使在苏氨酸的存在下。细胞皱缩实验表明，外源苏氨酸诱导的cothr4突变体的附着胞表现出低膨压产生。综上所述，这些结果表明，苏氨酸合酶CoThr4在C.圆形的
Upon recognition of host plants, Colletotrichum orbiculare, an anthracnose disease fungus of cucurbitaceous plants, initiates morphological differentiation, including conidial germination and appressorium formation on the cuticle layer. The series of infection processes of C. orbiculare requires enormous nutrient and energy, but the surface of the cucurbitaceous hosts is hardly nutrient-rich. Hence, C. orbiculare must exert tight management of its intracellular nutrients in order to properly induce infection-related morphogenesis. Here, we carried out a large-scale insertional mutagenesis screen using Agrobacterium tumefaciens-mediated transformation to identify novel genes involved in the pathogenicity of C. orbiculare and found that CoTHR4-encoded threonine synthase, a homolog of Saccharomyces cerevisiae THR4, is required for pathogenicity and conidiation in C. orbiculare. Threonine supplementation allowed the cothr4 mutant to produce conidia to a level equivalent to that of the wild-type. The conidia produced from the threonine-treated cothr4 mutant failed to germinate in the absence of threonine, but retained the ability to germinate and to form appressoria in the presence of threonine. However, the conidia produced from the threonine-treated cothr4 mutant remained attenuated in pathogenicity on cucumber cotyledons even in the presence of threonine. Cytorrhysis assays revealed that appressoria of the cothr4 mutant induced by exogenous threonine treatment showed low turgor generation. Taken together, these results showed that threonine synthase CoThr4 plays a pivotal role in infection-related morphogenesis during the prepenetration stage of C. orbiculare.