Takemoto Daigo, Jones David A, Hardham Adrienne R
Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, PO Box 475 Canberra, ACT 2601, Australia.
Plant J. 2003 Feb;33(4):775-92. doi: 10.1046/j.1365-313x.2003.01673.x.
Cytoplasmic aggregation, the rapid translocation of cytoplasm and subcellular components to the site of pathogen penetration, is one of the earliest reactions of plant cells against attack by microorganisms. We have investigated cytoplasmic aggregation during Arabidopsis-oomycete interactions. Infection by non-pathogenic Phytophthora sojae was prevented in the plant epidermal cell layer, whereas Peronospora parasitica isolates Cala2 (avirulent) and Noks1 (virulent) could both penetrate into the mesophyll cell layer. Epidermal cell responses to penetration by these oomycetes were examined cytologically with a range of transgenic Arabidopsis plants expressing Green Fluorescent Protein (GFP)-tagged cell components. These included plants containing GFP-TUA6 for visualizing microtubules, GFP-hTalin for actin microfilaments, GFP-tm-KKXX for endoplasmic reticulum (ER), and STtmd-GFP for the Golgi apparatus. In all interactions, actin microfilaments were actively re-arranged and formed large bundles in cytoplasmic strands focused on the penetration site. Aggregation of ER membrane and accumulation of Golgi bodies at the infection site were observed, suggesting that production and secretion of plant materials were activated around the penetration site. Microtubules did not become focused on the penetration site. No difference was evident between the responses of epidermal cells in the non-host, incompatible and compatible interactions. This result indicates that the induction of cytoplasmic aggregation in Arabidopsis epidermal cells was neither suppressed by the virulent strain of Peronospora, nor effective in stopping infection.
细胞质聚集，即细胞质和亚细胞成分迅速向病原体侵入部位转移，是植物细胞抵御微生物攻击的最早反应之一。我们研究了拟南芥与卵菌相互作用过程中的细胞质聚集。非致病性大豆疫霉在植物表皮细胞层的感染受到阻止，而寄生霜霉分离株Cala2（无毒）和Noks1（有毒）都能侵入叶肉细胞层。用一系列表达绿色荧光蛋白（GFP）标记细胞成分的转基因拟南芥植株，对这些卵菌侵入引起的表皮细胞反应进行了细胞学检查。这些植株包括含有用于观察微管的GFP-TUA6、用于肌动蛋白微丝的GFP-hTalin、用于内质网（ER）的GFP-tm-KKXX以及用于高尔基体的STtmd-GFP的植株。在所有相互作用中，肌动蛋白微丝都被积极重新排列，并在聚焦于侵入部位的细胞质丝中形成大束。观察到内质网膜在感染部位聚集以及高尔基体在感染部位积累，这表明在侵入部位周围植物物质的产生和分泌被激活。微管没有聚焦在侵入部位。在非寄主、不亲和和亲和相互作用中，表皮细胞的反应没有明显差异。这一结果表明，拟南芥表皮细胞中细胞质聚集的诱导既没有被寄生霜霉的有毒菌株抑制，也不能有效阻止感染。
