大丽轮枝菌侵染抗感棉种的组织学过程观察

 棉花黄萎病是一种极难防治的土传性真菌病害，研究病原菌侵染棉花的组织学过程对致病机理解析和抗病资源利用具有重要意义。本研究利用绿色荧光蛋白标记的大丽轮枝菌系统研究了其对抗病棉种海岛棉7124和三裂棉、感病棉种军棉1号和戴维逊棉的侵染过程。结果表明，大丽轮枝菌对抗/感棉种的初始侵染没有明显差异，接菌5 h后，分生孢子均能吸附在感病和抗病棉种的根表面。但侵染过程存在显著差异，侵染感病棉种中病原菌3~5 d到达皮层，5~7 d达到维管束，随后迅速扩展繁殖，侵染14 d后即完成系统侵染，并开始产生黄萎病症状;而病原菌侵染抗病棉种，5~7 d才侵入皮层，7~10 d到达维管束，14 d后仍无法扩展，病原菌的定殖与发展受到限制，无法形成系统侵染，较少形成黄萎病症状。本研究通过绿色荧光蛋白标记大丽轮枝菌对抗/感棉种的侵染过程研究，为大丽轮枝菌致病机理研究和抗性资源利用提供了强有力的理论依据。

Histological observation of cotton infected by Verticillium dahliae

Cotton wilt disease caused by the soil\|borne vascular wilt fungus is one of the most widespread and damaging diseases and difficult to control. It is beneficial to understand the pathogenesis and utilize the host resistance resource through the research on infection process. The green fluorescent protein\|tagged isolate of Verticillium dahliae was used for studying the infection process in different cotton species. The resistant cotton group containing Gossypium barbadense cv. Hai7124 and G. trilobum and susceptible one containing G. hirsutum cv. Junmian1 and G. davidsonii were used in the study. The results showed that there was no obvious difference in the initial invasion of V. dahliae when the conidia adsorbed on the root surface of all detected cotton 5 hours after inoculation. However, the infection process showed significant difference between susceptible and resistant cotton. In susceptible cotton, V. dahliae infiltrated into the cortex 3 to 5 days after inoculation, and colonized in the vascular 5 to 7 days after inoculation, then the pathogen was spread and reproduced quickly. The systemic infection achieved 14 days after inoculation and formed the symptom of verticillium wilt. The infection of V. dahliae to resistant cotton is a relatively slow process that the pathogen reached to cortex 5 to 7 days and to vascular tissue 7 to 10 days after inoculation. V. dahliae cannot spread 14 days after inoculation and difficult to finish the systemic infection. These results suggested that the structure, physiology and biochemistry of resistant cotton delayed the infection process compared with susceptible cotton. Therefore, the research of V. dahliae infection process to cotton is meaningful to the research of pathogenesis and the utilization of resistance resource.