To well cope with various external carbon sources, fungi have evolved an adaptive mechanism to overcome the adversity of carbon source deficiency. The sucrose non-fermenting (SNF1) protein kinase mainly mediates the utilization of non-fermentable carbon sources. In this study, we determined the function of Snf1, coding the α-subunit of SNF1 kinase, in the phytopathogenic fungus Alternaria alternata via analyzing the Snf1 deletion mutants (ΔAasnf1). Aasnf1 is required for growth, development of aerial mycelium, and conidiation. Results of pathogenicity test showed that ΔAasnf1 induced smaller lesions on detached citrus leaves. Moreover, in the carbon utilization assay, ΔAasnf1 showed growth inhibition on the minimal medium supplemented with polygalacturonic acid, sucrose or alcohol as the only carbon source. Compared to the wild type, ΔAasnf1 also exhibited stronger resistance to cell wall stressors of sodium dodecyl sulfate and congo red. In conclusion, Aasnf1 played important roles in the carbon utilization, vegetative growth, conidiation, cell wall functions and pathogenicity of A. alternata. This study is the first report on the functions of Aasnf1 and our results suggest that Snf1 is critical for the conidiogenesis and pathogenesis of the A. alternata tangerine pathotype.

中文翻译：

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编码 SNF1 激酶的 α-亚基，Snf1 是 Alternaria alternata 橘子病型的分生孢子发生和致病性所必需的

为了更好地应对各种外部碳源，真菌进化出一种适应机制来克服碳源缺乏的逆境。蔗糖非发酵 (SNF1) 蛋白激酶主要介导不可发酵碳源的利用。在这项研究中，我们通过分析 Snf1 缺失突变体 (ΔAasnf1) 确定了编码 SNF1 激酶 α 亚基的 Snf1 在植物病原真菌链格孢中的功能。Aasnf1 是生长、气生菌丝体发育和分生孢子所必需的。致病性试验结果表明，ΔAasnf1在离体柑橘叶片上诱导较小的病斑。此外，在碳利用测定中，ΔAasnf1 在补充有聚半乳糖醛酸、蔗糖或酒精作为唯一碳源的基本培养基上显示出生长抑制。与野生型相比，ΔAasnf1 还对十二烷基硫酸钠和刚果红的细胞壁应激物表现出更强的抵抗力。总之，Aasnf1在A.alternata的碳利用、营养生长、分生孢子、细胞壁功能和致病性中发挥了重要作用。这项研究是关于 Aasnf1 功能的第一份报告，我们的结果表明 Snf1 对于 A. alternata tangerine 病理型的分生孢子发生和发病机制至关重要。