Usman Sayed, Ge Xinwei, Xu Yueqiang, Qin Qijian, Xie Jin, Wang Bin, Jin Cheng, Fang Wenxia
College of Life Science and Technology, Guangxi University, Nanning 530004, China.
Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning 530007, China.
J Fungi (Basel). 2023 Apr 16;9(4):478. doi: 10.3390/jof9040478.
f. sp. tropical race 4 ( TR4) causes Fusarium wilt of banana, necessitating urgent measures to control this disease. However, the molecular mechanisms underlying TR4 virulence remain elusive. Phosphomannose isomerase is a key enzyme involved in the biosynthesis of GDP mannose, an important precursor of fungal cell walls. In this study, two phosphomannose isomerases were identified in the TR4 genome, of which only was highly expressed throughout all developmental stages. Generated null mutants in TR4 showed that only the Δ mutant required exogenous mannose for growth, indicating that is the key enzyme involved in GDP mannose biosynthesis. The deficient strain was unable to grow without exogenous mannose and exhibited impaired growth under stress conditions. The mutant had reduced chitin content in its cell wall, rendering it vulnerable to cell wall stresses. Transcriptomic analysis revealed up- and down-regulation of several genes involved in host cell wall degradation and physiological processes due to the loss of . Furthermore, was also found to be crucial for TR4 infection and virulence, making it a potential antifungal target to address the threats posed by TR4.
尖孢镰刀菌热带4号小种（TR4）引发香蕉枯萎病，因此需要采取紧急措施来控制这种病害。然而，TR4致病力的分子机制仍不清楚。磷酸甘露糖异构酶是参与GDP甘露糖生物合成的关键酶，而GDP甘露糖是真菌细胞壁的重要前体。在本研究中，在TR4基因组中鉴定出两种磷酸甘露糖异构酶，其中只有一种在所有发育阶段均高表达。在TR4中产生的基因敲除突变体表明，只有Δ突变体生长需要外源甘露糖，这表明该基因是参与GDP甘露糖生物合成的关键酶。缺乏该基因的菌株在没有外源甘露糖的情况下无法生长，并且在胁迫条件下生长受损。该突变体细胞壁中的几丁质含量降低，使其易受细胞壁胁迫。转录组分析显示，由于该基因缺失，参与宿主细胞壁降解和生理过程的几个基因出现上调和下调。此外，还发现该基因对TR4的侵染和致病力至关重要，使其成为应对TR4威胁的潜在抗真菌靶点。
