Mol Plant Microbe Interact. 2014 Jun;27(6):590-600. doi: 10.1094/MPMI-10-13-0314-R.
Pathogenic fungi usually secrete a series of virulence factors to the extracellular environment to facilitate infection. Rab GTPases play a central role in the secretory pathway. To explore the function of Rab/GTPase in filamentous fungi, we knocked out a Rab/GTPase family gene, Bcsas1, in Botrytis cinerea, an aggressive fungal pathogen that infects more than 200 plant species. A detailed analysis was conducted on the virulence and the secretory capability of the mutants. The results indicated that knockout of Bcsas1 inhibited hyphal development and reduced sporulation of B. cinerea on potato dextrose agar plates resulting in reduced virulence on various fruit hosts. Knocking out the Bcsas1 gene led to an accumulation of transport vesicles at the hyphal tip, significantly reduced extracellular protein content, and lowered the activity of polygalacturonase and xylanase in the extracellular medium. However, mutation of Bcsas1 did not affect the expression of genes encoding polygalacturonase and xylanase, suggesting the secretion of these two family enzymes was suppressed in the mutant. Moreover, a comparative analysis of the secretome provided further evidence that the disruption of Bcsas1 in mutant strains significantly depressed the secretion of polysaccharide hydrolases and proteases. The results indicate that Bcsas1, the Rab8/SEC4-like gene, plays a crucial role in development, protein secretion, and virulence of B. cinerea.
致病真菌通常会向细胞外环境分泌一系列毒力因子，以促进感染。Rab GTPases 在分泌途径中起着核心作用。为了探索 Rab/GTPase 在丝状真菌中的功能，我们敲除了 Botrytis cinerea 中的 Rab/GTPase 家族基因 Bcsas1，B. cinerea 是一种侵袭性真菌病原体，可感染 200 多种植物。我们对突变体的毒力和分泌能力进行了详细分析。结果表明，敲除 Bcsas1 抑制了菌丝发育，减少了 B. cinerea 在马铃薯葡萄糖琼脂平板上的孢子形成，导致对各种水果宿主的毒力降低。敲除 Bcsas1 基因导致运输小泡在菌丝顶端积累，显著降低了细胞外蛋白含量，并降低了细胞外介质中多聚半乳糖醛酸酶和木聚糖酶的活性。然而，Bcsas1 突变不影响编码多聚半乳糖醛酸酶和木聚糖酶的基因的表达，表明这两种家族酶的分泌在突变体中受到抑制。此外，对分泌组的比较分析进一步提供了证据，表明突变菌株中 Bcsas1 的破坏显著抑制了多糖水解酶和蛋白酶的分泌。结果表明，Rab8/SEC4 样基因 Bcsas1 在 B. cinerea 的发育、蛋白质分泌和毒力中起着关键作用。
