Ding Jie, Mei Jie, Huang Pei, Tian Ying, Liang Yao, Jiang Xiliang, Li Mei
Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2 West Yuanmingyuan Rd., Haidian District, Beijing, 100193, China.
College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming, 650201, China.
AMB Express. 2020 Dec 17;10(1):221. doi: 10.1186/s13568-020-01162-9.
Heterotrimeric G-proteins are key elements of signal transduction pathways, which participate in regulating multiple biological processes in fungi including growth, conidiation, antagonism, and mycoparasitism. Among G protein subunits, Gα3 showed diverse regulatory functions in different fungi. In this study, we cloned a Gα3 subunit coding gene thga3 from T. harzianum Th33 that can antagonize Rhizoctonia solani and some other plant pathogenic fungi. A thga3 deletion strain Δthga3 was generated using the double-crossover homologous recombination strategy, and Rthga3 was generated by transforming thga3-expressing vector into the protoplasts of Δthga3 by the PEG/CaCl-mediated method. The biological characteristics of wild-type Th33, Δthga3 and Rthga3 were evaluated. Compared with wild-type Th33, Δthga3 showed 15%, 94%, and 23% decrease in hyphal growth, conidia yield, and chitinase activity, respectively, and Δthga3 showed lower antagonistic and mycoparasitism abilities, while there were no significant differences between wild-type Th33 and Rthga3. The hyphal surface hydrophobicity of Δthga3 significantly decreased compared with those of the wild-type Th33 and Rthga3. qRT-PCR analysis revealed that transcript abundance of the hydrophobin gene (tha_09745) of Δthga3 decreased by 80% compared with that of wild-type Th33 and Rthga3. The results showed that thga3 positively regulates the growth, conidiation, hydrophobicity, chitinase activities, and mycoparasitism of Th33 towards R. solani. We hence deduced that the expression level of Tha_09745 is correlated to the hyphal hydrophobicity of Th33 and therefore affects the other biological characteristics of Th33. The findings of this report provide a foundation for elucidating the G-protein signal regulatory mechanisms of fungi.
异源三聚体G蛋白是信号转导途径的关键元件，参与调节真菌中的多种生物学过程，包括生长、产孢、拮抗作用和重寄生作用。在G蛋白亚基中，Gα3在不同真菌中表现出多种调节功能。在本研究中，我们从哈茨木霉Th33中克隆了一个编码Gα3亚基的基因thga3，该菌株能够拮抗立枯丝核菌和其他一些植物病原真菌。使用双交换同源重组策略构建了thga3缺失菌株Δthga3，并通过PEG/CaCl介导的方法将thga3表达载体转化到Δthga3的原生质体中，获得了互补菌株Rthga3。对野生型Th33、Δthga3和Rthga3的生物学特性进行了评估。与野生型Th33相比，Δthga3的菌丝生长、分生孢子产量和几丁质酶活性分别降低了15%、94%和23%，并且Δthga3表现出较低的拮抗和重寄生能力，而野生型Th33和Rthga3之间没有显著差异。与野生型Th33和Rthga3相比，Δthga3的菌丝表面疏水性显著降低。qRT-PCR分析表明，Δthga3的疏水蛋白基因（tha_09745）的转录丰度与野生型Th33和Rthga3相比降低了80%。结果表明，thga3正向调节Th33对立枯丝核菌的生长、产孢、疏水性、几丁质酶活性和重寄生作用。因此，我们推断Tha_09745的表达水平与Th33的菌丝疏水性相关，进而影响Th33的其他生物学特性。本报告的研究结果为阐明真菌的G蛋白信号调节机制提供了基础。
