Department of Plant Pathology, The Pennsylvania State University, University Park, PA, USA.
Mol Plant Microbe Interact. 2011 Jun;24(6):719-32. doi: 10.1094/MPMI-11-10-0267.
The soilborne fungal pathogen Fusarium oxysporum causes vascular wilt and root rot diseases in many plant species. We investigated the role of cyclic AMP-dependent protein kinase A of F. oxysporum (FoCPKA) in growth, morphology, and root attachment, penetration, and pathogenesis in Arabidopsis thaliana. Affinity of spore attachment to root surfaces of A. thaliana, observed microscopically and measured by atomic force microscopy, was reduced by a loss-of-function mutation in the gene encoding the catalytic subunit of FoCPKA. The resulting mutants also failed to penetrate into the vascular system of A. thaliana roots and lost virulence. Even when the mutants managed to enter the vascular system via physically wounded roots, the degree of vascular colonization was significantly lower than that of the corresponding wild-type strain O-685 and no noticeable disease symptoms were observed. The mutants also had reduced vegetative growth and spore production, and their hyphal growth patterns were distinct from those of O-685. Coinoculation of O-685 with an focpkA mutant or a strain nonpathogenic to A. thaliana significantly reduced disease severity and the degree of root colonization by O-685. Several experimental tools useful for studying mechanisms of fungal root pathogenesis are also introduced.
土壤真菌病原体尖孢镰刀菌（Fusarium oxysporum）可引起许多植物物种的维管束萎蔫病和根腐病。我们研究了尖孢镰刀菌环腺苷酸依赖性蛋白激酶 A（FoCPKA）在拟南芥生长、形态以及根附着、穿透和发病机制中的作用。通过编码 FoCPKA 催化亚基的基因功能丧失突变，观察到附着在拟南芥根表面的孢子的亲和力降低，通过原子力显微镜进行微观观察和测量。由此产生的突变体也无法穿透到拟南芥根的维管束系统，并且失去了毒力。即使突变体通过物理损伤的根进入维管束系统，其对维管束的定殖程度也明显低于相应的野生型 O-685 菌株，也没有观察到明显的疾病症状。突变体的营养生长和孢子产生也减少，其菌丝生长模式也与 O-685 不同。将 O-685 与 focpkA 突变体或对拟南芥无毒的菌株共同接种可显著降低疾病严重程度和 O-685 对根的定殖程度。还介绍了几种用于研究真菌根发病机制的实验工具。
