Fan Xiaoning, Zhang Penghui, Batool Wajjiha, Liu Chang, Hu Yan, Wei Yi, He Zhengquan, Zhang Shi-Hong
The Key Laboratory for Extreme-Environmental Microbiology, College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China.
Key Laboratory of Three Gorges Regional Plant Genetics & Germplasm Enhancement (CTGU), Biotechnology Research Center, China Three Gorges University, Yichang 443000, China.
J Fungi (Basel). 2023 Feb 28;9(3):311. doi: 10.3390/jof9030311.
Dihydroxynapthalene-(DHN) and L-dihydroxyphenylalanine (L-DOPA) are two types of dominant melanin in fungi. Fungal melanins with versatile functions are frequently associated with pathogenicity and stress tolerance. In rice blast fungus, , DHN melanin is essential to maintain the integrity of the infectious structure, appressoria; but the role of the tyrosinase-derived L-DOPA melanin is still unknown. Here, we have genetically and biologically characterized a tyrosinase gene () in . . encodes a protein of 719 amino acids that contains the typical CuA and CuB domains of tyrosinase. The deletion mutant of MoTyr (Δ) was obtained by using a homologous recombination approach. Phenotypic analysis showed that conidiophore stalks and conidia formation was significantly reduced in Δ. Under different concentrations of glycerol and PEG, more appressoria collapsed in the mutant strains than in the wild type, suggesting MoTyr is associated with the integrity of the appressorium wall. Melanin measurement confirmed that MoTyr loss resulted in a significant decrease in melanin synthesis. Accordingly, the loss of MoTyr stunted the conidia germination under stress conditions. Importantly, the MoTyr deletion affected both infection and pathogenesis stages. These results suggest that MoTyr, like DHN pigment synthase, plays a key role in conidiophore stalks formation, appressorium integrity, and pathogenesis of . , revealing a potential drug target for blast disease control.
二羟基萘（DHN）和L - 二羟基苯丙氨酸（L - DOPA）是真菌中两种主要的黑色素类型。具有多种功能的真菌黑色素常与致病性和胁迫耐受性相关。在稻瘟病菌中，DHN黑色素对于维持侵染结构附着胞的完整性至关重要；但酪氨酸酶衍生的L - DOPA黑色素的作用仍不清楚。在此，我们对稻瘟病菌中的一个酪氨酸酶基因（）进行了遗传学和生物学特征分析。 编码一个含有719个氨基酸的蛋白质，该蛋白质包含酪氨酸酶典型的CuA和CuB结构域。通过同源重组方法获得了MoTyr的缺失突变体（Δ）。表型分析表明，Δ中分生孢子梗和分生孢子的形成显著减少。在不同浓度的甘油和聚乙二醇下，突变菌株中比野生型有更多的附着胞塌陷，这表明MoTyr与附着胞壁的完整性有关。黑色素测定证实MoTyr缺失导致黑色素合成显著减少。因此，MoTyr缺失使胁迫条件下分生孢子的萌发受到抑制。重要的是，MoTyr缺失影响了侵染和致病阶段。这些结果表明，MoTyr与DHN色素合酶一样，在稻瘟病菌的分生孢子梗形成、附着胞完整性和致病过程中起关键作用，揭示了一个控制稻瘟病的潜在药物靶点。
