ABSTRACT

Fungal plant pathogens deploy a suite of secreted proteins, called effectors, to facilitate successful infection. Several fungal pathogens have been reported to secrete and accumulate their effector proteins in the host–pathogen interfacial spaces. Previously, we reported that the strain 104-T of the cucurbit anthracnose pathogen Colletotrichum orbiculare secretes and accumulates mCherry-tagged effectors along with the formation of ring-shaped fluorescence signals beneath the appressoria. However, it was unclear whether these effector accumulation patterns occur in other C. orbiculare isolates and other species belonging to the Colletotrichum genus. Here, we investigated the effector localization during host infection of C. orbiculare MAFF306589, C. trifolii MAFF305078, which infects alfalfa, and C. higginsianum MAFF305635, which infects Brassicaceae plants. We generated effector–reporter lines of each species, which constitutively expressed mCherry-tagged CoDN3 effector (CoDN3:mCherry). Immunoblotting analysis of the liquid culture fluids of the generated lines detected CoDN3:mCherry, which confirmed secretion of CoDN3:mCherry by fungal cells. Via inoculation assays in the corresponding host plants, we detected ring-shaped CoDN3:mCherry fluorescence around the appressorial invasion sites in all tested reporter lines. These results suggest that pathogens in the Colletotrichum genus have evolutionarily conserved the trait of effector secretion in the infection stage irrespective of differences in their hosts.

 抽象的

真菌植物病原体利用一套称为效应器的分泌蛋白来促进成功感染。据报道，几种真菌病原体在宿主-病原体界面空间中分泌并积累其效应蛋白。此前，我们报道了葫芦炭疽病病原体Colletotrichum orbicale的菌株104-T分泌并积累mCherry标记的效应子，同时在附着胞下方形成环形荧光信号。然而，尚不清楚这些效应子积累模式是否发生在其他C. orbulare分离株和属于炭疽菌属的其他物种中。在这里，我们研究了感染苜蓿的C. orbicale MAFF306589、 C. trifolii MAFF305078 和感染十字花科植物的C. higginsianum MAFF305635 在宿主感染期间的效应子定位。我们生成了每个物种的效应子-报告子系，其组成型表达 mCherry 标记的 CoDN3 效应子 (CoDN3:mCherry)。对所产生的细胞系的液体培养液进行免疫印迹分析，检测到 CoDN3:mCherry，这证实了真菌细胞分泌 CoDN3:mCherry。通过在相应宿主植物中进行接种测定，我们在所有测试的报告系中检测到附着侵入位点周围的环形 CoDN3:mCherry 荧光。这些结果表明，炭疽菌属的病原体在进化上保留了感染阶段的效应物分泌特征，无论其宿主有何差异。