The cAMP Signaling Pathway in Fusarium verticillioides Is Important for Conidiation, Plant Infection, and Stress Responses but Not Fumonisin Production
The cAMP Signaling Pathway in Fusarium verticillioides Is Important for Conidiation, Plant Infection, and Stress Responses but Not Fumonisin Production
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DOI：
10.1094/mpmi-23-4-0522
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发表时间：
2010-04-01
影响因子：
3.5
通讯作者：
Xu, Jin-Rong
中科院分区：
文献类型：
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作者：
Choi, Yoon-E;Xu, Jin-Rong
黄萎病镰刀菌是玉米最重要的病原菌之一。该病原体产生的霉菌毒素、伏马菌素对人类和动物健康构成威胁。由于CAMP信号通路参与真菌病原体的多种发育和感染过程的调节，在本研究中，我们旨在阐明CAMP-蛋白激酶A （PKA）通路在黄萎病菌毒素产生和植物感染中的功能。CPK1和FAC1基因分别编码PKA和腺苷酸环化酶的催化亚基，产生了靶向缺失突变体。在cpk1和fac1缺失突变体中均观察到径向生长和大孢子发育缺陷。事实上，突变体的毒力和微孢子作用也显著降低，但耐热性和氧化胁迫能力增强。在cpk1突变体中没有观察到这些表型，这表明PKA必须存在其他催化亚基，并在FAC1下游发挥作用。突变体主要在假头中形成微分生孢子。在事实突变体中，已知与微分生孢子形成变化相关的恐水基因HYD1和HYD2的表达水平显著降低。在FAC1突变体中，另外两个被认为是FAC1下游靶点的F. verticillioides GSY2和HSP26基因的表达增加，这可能与FAC1突变体的抗逆性增强有关。尽管伏马菌素的产生是正常的，但在fact突变体中，比卡维林的生物合成增加，这表明fact和cAMP信号可能在次生代谢中具有通路或代谢物特异性的调节作用。总的来说，事实缺失突变体的多效性缺陷表明cAMP-PKA途径参与了黄萎病菌的生长、分生、bikaverin的产生和植物感染。
Fusarium verticillioides is one of the most important fungal pathogens of maize. Mycotoxin, fumonisins produced by this pathogen pose a threat to human and animal health. Because CAMP signaling has been implicated in regulating diverse developmental and infection processes in fungal pathogens, in this study, we aimed to elucidate the function of the CAMP-protein kinase A (PKA) pathway in toxin production and plant infection in h: verticillioides. Targeted deletion mutants were generated for the CPK1 and FAC1 genes that encode a catalytic subunit of PKA and the adenylate cyclase, respectively. Defects in radial growth and macroconidiation were observed in both the cpk1 and fac1 deletion mutants. The fact mutant also was significantly reduced in virulence and microconidiation but increased in tolerance to heat and oxidative stresses. These phenotypes were not observed in the cpk1 mutant, indicating that additional catalytic subunit of PKA must exist and function downstream from FAC1. The fact mutant formed microconidia mainly in false heads. The expression levels of the hydrophobia genes HYD1 and HYD2, which are known to be associated with change in formation of microconidia, were significantly reduced in the fact mutant. Expression of F. verticillioides GSY2 and HSP26 genes, two other putative downstream targets of FAC1, was increased in the fac1 mutant and may be associated with its enhanced stress tolerance. Although fumonisin production was normal, biosynthesis of bikaverin was increased in the fact mutant, suggesting that FACT and cAMP signaling may have pathway- or metabolite-specific regulatory roles in secondary metabolism. Overall, the pleiotropic defects of the fact deletion mutant indicate that the cAMP-PKA pathway is involved in growth, conidiation, bikaverin production, and plant infection in F. verticillioides.