Stergiopoulos Ioannis, Zwiers Lute-Harm, De Waard Maarten A
Laboratory of Phytopathology, Department of Plant Sciences, Wageningen University, Binnenhaven 5, 6709 PD, P.O. Box 8025, 6700 EE Wageningen, The Netherlands.
Mol Plant Microbe Interact. 2003 Aug;16(8):689-98. doi: 10.1094/MPMI.2003.16.8.689.
The role in virulence of the ATP-binding cassette (ABC) transporters MgAtr1, MgAtr2, MgAtr3, MgAtr4, and MgAtr5 from Mycosphaerella graminicola was analyzed by gene disruption or replacement on seedlings of the susceptible wheat cultivar Obelisk. Disruption strains of MgAtr1 and MgAtr2 and replacement strains of MgAtr3 and MgAtr5 displayed the same phenotype as control strains, while virulence of the MgAtr4 disruption strains was significantly reduced. This reduction in virulence was independent of the wheat cultivar used. Histopathological analysis of the infection process revealed that MgAtr4 disruption strains colonize substomatal cavities less efficiently and display reduced intercellular growth in the apoplast of wheat leaves. In vitro growth experiments in different media showed no fitness penalty associated with the disruption of MgAtr4. Expression analysis demonstrated that transcripts of the constitutively expressed gene CYP51 encoding the fungal-specific cytochrome P450 sterol 14alpha-demethylase from M. graminicola were not detectable in interaction RNA from wheat infected with MgAtr4 disruption strains, thus confirming the reduced intercellular growth of these strains. The results indicate that MgAtr4 is a virulence factor of M. graminicola during pathogenesis on wheat and may function in protection against fungitoxic compounds present around the substomatal cavities of wheat leaves. MgAtr4 is the first virulence factor cloned from this important plant pathogen.
通过对小麦感病品种“方尖碑”幼苗进行基因破坏或替换，分析了禾顶囊壳菌的ATP结合盒（ABC）转运蛋白MgAtr1、MgAtr2、MgAtr3、MgAtr4和MgAtr5在毒力中的作用。MgAtr1和MgAtr2的破坏菌株以及MgAtr3和MgAtr5的替换菌株表现出与对照菌株相同的表型，而MgAtr4破坏菌株的毒力显著降低。这种毒力降低与所用小麦品种无关。对感染过程的组织病理学分析表明，MgAtr4破坏菌株在气孔下腔的定殖效率较低，且在小麦叶片质外体中的细胞间生长减少。在不同培养基中的体外生长实验表明，MgAtr4的破坏没有导致适应性缺陷。表达分析表明，在感染MgAtr4破坏菌株的小麦的互作RNA中，检测不到禾顶囊壳菌中组成型表达的编码真菌特异性细胞色素P450甾醇14α-脱甲基酶的基因CYP51的转录本，从而证实了这些菌株细胞间生长的减少。结果表明，MgAtr4是禾顶囊壳菌在小麦致病过程中的一个毒力因子，可能在保护细胞免受小麦叶片气孔下腔周围存在的真菌毒性化合物的侵害中发挥作用。MgAtr4是从这种重要植物病原菌中克隆出的首个毒力因子。
