FoSTUA, encoding a basic helix-loop-helix protein, differentially regulates development of three kinds of asexual spores, macroconidia, microconidia, and chlamydospores, in the fungal plant pathogen Fusarium oxysporum
FoSTUA, encoding a basic helix-loop-helix protein, differentially regulates development of three kinds of asexual spores, macroconidia, microconidia, and chlamydospores, in the fungal plant pathogen Fusarium oxysporum
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DOI：
10.1128/ec.3.6.1412-1422.2004
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发表时间：
2004-12-01
期刊：
影响因子：
--
通讯作者：
Tsuge, T
中科院分区：
文献类型：
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作者：
Ohara, T;Tsuge, T
土传真菌尖孢镰刀菌可引起多种植物的维管束枯萎。尖孢镰刀菌产生三种无性孢子：大孢子、小孢子和厚壁孢子。大分生孢子一般由分生孢子梗上的顶生分生孢子形成，很少由菌丝上的中间分生分生孢子形成。椭圆形微孢子是由菌丝上的菌丝形成的。厚壁球形厚壁孢子是由菌丝和分生孢子细胞改造而成。在这里，我们描述了尖孢镰刀菌的FoSTUA，它对大孢子、小孢子和厚壁孢子的发育有不同的调节作用。FoSTUA编码一种基本的螺旋-环-螺旋蛋白，与Nidulans Stua相似，已被鉴定为控制分生孢子形成的转录调节因子。利用表达FoStuA-绿色荧光蛋白融合蛋白的菌株验证了FoStuA的核定位。以FoSTUA为靶标的突变体在培养中表现出正常的微孢子形成。然而，突变体缺乏分生孢子，并且只从中间分生孢子产生低频率的大分生孢子。因此，FoSTUA似乎是诱导分生孢子分化所必需的。相反，在突变体中厚垣孢子的形成被显著地促进。这些结果表明，FoStuA对大孢子和厚壁孢子的发育分别是一个正调控因子和一个负调控因子，对小孢子的形成是必不可少的。尖孢镰刀菌的致病能力不受FoSTUA突变的影响。然而，突变体在感染植株中产生的大孢子和小孢子明显少于野生型。这些结果表明，FoSTUA对微孢子的形成也有重要作用，尤其是在受感染的植物中。
The soil-borne fungus Fusarium oxysporum causes vascular wilt of a wide variety of plant species. F. oxysporum produces three kinds of asexual spores, macroconidia, microconidia, and chlamydospores. Falcate macroconidia are formed generally from terminal phialides on conidiophores and rarely from intercalary phialides on hyphae. Ellipsoidal microconidia are formed from intercalary phialides on hyphae. Globose chlamydospores with thick walls are developed by the modification of hyphal and conidial cells. Here we describe FoSTUA of F. oxysporum, which differentially regulates the development of macroconidia, microconidia, and chlamydospores. FoSTUA encodes a basic helix-loop-helix protein with similarity to Aspergillus nidulans StuA, which has been identified as a transcriptional regulator controlling conidiation. Nuclear localization of FoStuA was verified by using strains expressing FoStuA-green fluorescent protein fusions. The FoSTUA-targeted mutants exhibited normal microconidium formation in cultures. However, the mutants lacked conidiophores and produced macroconidia at low frequencies only from intercalary phialides. Thus, FoSTUA appears to be necessary to induce conidiophore differentiation. In contrast, chlamydospore formation was dramatically promoted in the mutants. These data demonstrate that FoStuA is a positive regulator and a negative regulator for the development of macroconidia and chlamydospores, respectively, and is dispensable for microconidium formation in cultures. The disease-causing ability of F. oxysporum was not affected by mutations in FoSTUA. However, the mutants produced markedly fewer macroconidia and microconidia in infected plants than the wild type. These results suggest that FoSTUA also has an important role for microconidium formation specifically in infected plants.