Van de Wouw Angela P, Pettolino Filomena A, Howlett Barbara J, Elliott Candace E
School of Botany, The University of Melbourne, Vic., Australia.
Fungal Genet Biol. 2009 Sep;46(9):695-706. doi: 10.1016/j.fgb.2009.06.004. Epub 2009 Jun 17.
Maintaining cell wall integrity is essential for fungal growth and development. We describe two mutants with altered expression of a gene, LmIFRD, from the ascomycete Leptosphaeria maculans. Truncation of the LmIFRD transcript in a T-DNA insertional mutant led to slower germination, less sporulation and loss-of-pathogenicity towards Brassica napus, whereas silencing of the LmIFRD transcript led to increased germination, sporulation and earlier infection. The increased tolerance to cell wall lysing enzymes and cell wall-disrupting compounds of the T-DNA mutant contrasts with decreased tolerance of the silenced mutant and suggests altered cell wall integrity and accessibility to 1,3-linked glucan and chitin. Lectin binding experiments and monosaccharide analysis revealed altered polysaccharide content and structure within the cell wall of the LmIFRD mutants, notably increased 1,3-linked galactose and chitin within the cell wall of the T-DNA mutant. This is the first analysis of monosaccharide linkage composition of cell walls of spores and mycelia for any dothideomycete.
维持细胞壁完整性对于真菌的生长和发育至关重要。我们描述了两个来自子囊菌大斑壳针孢（Leptosphaeria maculans）的基因LmIFRD表达发生改变的突变体。在一个T-DNA插入突变体中，LmIFRD转录本的截断导致萌发变慢、产孢减少以及对甘蓝型油菜的致病性丧失，而LmIFRD转录本的沉默则导致萌发增加、产孢增加以及感染提前。T-DNA突变体对细胞壁裂解酶和细胞壁破坏化合物的耐受性增加，与沉默突变体的耐受性降低形成对比，这表明细胞壁完整性以及对1,3-连接的葡聚糖和几丁质的可及性发生了改变。凝集素结合实验和单糖分析揭示了LmIFRD突变体细胞壁内多糖含量和结构的改变，特别是T-DNA突变体细胞壁内1,3-连接的半乳糖和几丁质增加。这是对任何座囊菌纲真菌的孢子和菌丝体细胞壁单糖连接组成的首次分析。
