小麦品种对条锈病低反应型抗性的组织学和超微结构研究

 采用荧光显微镜、微分干涉显微镜和电子显微镜技术 ,系统研究了非亲和组合中小麦对条锈病低反应型抗性的组织学和超微结构特征。非亲和组合分别由小麦品种牛朱特与条中 2 8号小种、杂种 4 6与条中 2 9号小种、天选 882与条中 2 9号小种组成 ,对照亲和组合由小麦品种辉县红与条中 2 9号小种组成。观察结果表明 ,小麦条锈菌在感病品种和抗病品种上发育的组织学和超微结构特征有明显差异。病菌在抗病品种上表现为菌丝生长受抑 ,菌落形成延迟或败育 ,病菌吸器母细胞和吸器数量明显减少。寄主细胞的坏死与条锈菌的发育受阻密切相关 ,免疫组合中病菌的受抑程度高于近免疫组合的。电镜观察发现 ,在抗病品种上 ,病菌胞间菌丝、吸器母细胞、吸器在细胞和亚细胞水平 ,均发生了一系列异常变化 ,其中包括原生质的电子致密度加深、液泡增多变大、菌丝细胞壁不规则增厚、细胞器排列紊乱及解体、吸器母细胞及吸器丧失其生理功能、病菌最终畸形坏死。同时发现抗病品种受病菌侵染时可迅速产生结构防卫反应 ,新形成胞壁沉积物和吸器鞘等结构 ,以阻碍病菌进一步的扩展与发育。就小麦品种与条锈菌非亲和组合中表现出的组织学和细胞学特征与小麦抗锈性表达的关系进行了讨论。

Histology and Ultrastructure of Incompatible Combination Between Puccinia striiformis and Wheat Cultivars with Resistance of Low Reaction Type

The incompatible combinations between races of Puccinia striiformis and wheat cultivars with resistance of low reaction type was examined by means of fluorescent microscopy, differential interference contrast microscopy, and electron microscopy. The incompatible combinations consisted of wheat cultivar Niuzhute plus CY28, Hybrid46 plus CY29 and Tianxuan882 plus CY29, while the compatible combination was wheat cultivar Huixianhong plus CY28. The observation revealed a striking difference in the fungal development and the host responses between susceptible and resistant wheat cultivars following infection by the pathogen. The main histological manifestation of the pathogen development in the resistant wheat cultivars include inhibition of hyphal growth, delay of hyphal branching and colony formation, decrease of formation of haustorial mother cells and haustoria, and occurrence of host cell necrosis. The observation by electron microscopy demonstrated that a series of abnormal changes occurred in intercellular hyphae, haustorial mother cells and haustoria during pathogen development in the resistant wheat cultivars. The cytoplasm became more electron-dense and vacuoles in the cytoplasm increased in number and in size. The cell walls of hyphae, haustorial mother cells were thickened irregularly. The organelles were distributed disorderly in the cytoplasm and the haustorial mother cells and haustoria lost their physiological function. In the final stage of the pathogen development, the intercellular hyphae, haustorial mother cells and haustoria became necrotic and collapsed. The structural defense reactions such as formation of cell wall apposition, collar, andencasement of haustorium were essentially more pronounced in the infected wheat leaves of the resistant cultivars than in the susceptible one. In addition, the relationship between the host resistance express and the histological and cytological features occurred in the incompatible combination was discussed in this paper.