【作者】 王兰；

【导师】 康振生； 黄丽丽；

【作者基本信息】 西北农林科技大学 ， 植物病理学， 2002， 硕士

【摘要】 由新月弯孢菌[Curvularia lunata(Wakker)Boed.]引起的玉米叶斑病是近年来我国北方玉米产区流行的一种重要病害。自70年代末80年代初在山东沿海发生此病以来，已不断向其它地区扩展为害，对玉米生产造成了很大损失。本文采用电镜技术和细胞化学技术对该菌的侵染行为及寄主受侵染后的细胞反应进行了观察，初步揭示了玉米与弯孢菌之间的互作关系。观察发现，玉米弯孢菌叶斑菌分生孢子萌发多数产生1个芽管，偶尔有双芽管，芽管生长很快，并不断形成分支和附着胞，从表皮直接侵入寄主。病菌侵入寄主后可在细胞内及细胞间扩展。在病菌扩展过程中，玉米细胞发生了一系列的病变反应，包括细胞壁加厚，质膜断裂，细胞器解体及细胞坏死等组织病变。细胞化学标记观察发现，病变组织细胞壁中纤维素、木聚糖和果胶质的标记密度明显低于未接种的健康组织，表明玉米弯孢菌在侵染叶片组织的过程中，分泌了细胞壁降解酶如纤维素酶、木聚糖酶和果胶酶等。这些酶的产生有利于病原菌在寄主组织中的侵染和扩展。 采用电子显微镜技术和细胞化学技术，研究了杀菌剂粉锈宁对新月弯孢菌在活体外生长发育的影响。光镜和扫描电镜观察结果表明，新月弯孢菌经粉锈宁处理后，病菌生长受到抑制，菌丝的生长速度减慢、分枝增多，菌丝不规则地肿大和缢缩，表面出现瘤状突起。透射电镜观察发现，药剂可引起菌丝细胞壁不规则增厚，顶端细胞壁增厚尤为明显，菌丝隔膜发育受阻而表现畸形。细胞化学标记定位分析结果表明，药剂处理后，菌丝细胞壁的β-1，3-葡聚糖和几丁质含量发生显著变化，β-1，3-葡聚糖和几丁质的标记密度明显低于对照菌丝。病菌细胞壁组成成分的改变进一步证实了三唑类杀菌剂能够影响病菌质膜结构与功能。 人工接种条件下，以感病品种腋单13为对照品种，对21个玉米品种在苗期及成株期对弯孢菌叶斑病抗性进行了综合分析。SSR检验结果表明，不同品种间抗病性存在明显差异；苗期抗病性表现较好的品种有丹玉13、中单2号、陕单911、农大60、西农11、秦四；成株期抗病性表现较好的品种有西农11、沈10、豫22、丹玉13、7098；苗期与成株期抗病性均表现较好的品种有丹玉13、西农11。更多还原

【Abstract】 Maize leaf spot infected by Curvularia lunata (Wakker) Boedis one of the most important diseases of poplar in the north of china recently. Since it was found in seaboard of Shandong from the end of 1970s to the beginning of 1980s, it has spread out toward many regions, and caused great yield loss in maize. In this paper, the infection and the main cellular events during the pathogen colonization were observed by means of electron microscopy and cytochemical labeling techniques. It was observed by electron microscopy that one germ tube, occasionally along with two, development from a germinated spore. The germ tube grew rapidly and formed considerable branched. The penetration of germ tube passed through epidermal cell but not stomata. After invasion of the pathogen into host, intercellular hyphae extended at first between host cells, then infected dead host cells and produced intracellular hyphae in host cells. During extension of the hyphae, series of pathological changes in the infected tissues of the host were observed, and the host cells died and digested finally, probably resulting from the toxin secreted by the pathogen. The cell wall components cellulose, xylan, spectin in cell walls of uninoculated healthy and C.lunata-infected leaf tissue were detected by means of cytochemical technique. It showed that the labeling densities for cellulose, xylan, spectin were significantly reduced as compared with corresponding cell walls of healthy leaf issue, indicating that C.lunata secreted cell wall-degrading enzymes such as cellulases, xylanases, pectinases during infection of the leaf issue, which decomposed and softened the host cell walls, then contributed to the penetration and extension of pathogen.The effects of triadimefon, a systemic fungicide from the triazol group, were examined on morphology, structure and cell wall components of Curvularia lunata by means of electron microscopy and cytochemical labelling techniques. The studies revealed that triadimefon not only inhibited the hyphal growth but also caused a series of marked morphological and structural alterations of hyphae. These changes included irregular swelling, excessive branching and many tumors on the surface of hyphae, considerable thickening of the hyphal cell walls, particularly at the hyphal tip region. The septum development of the hyphae was inhibited and became malformed. Forthermore,using cytochemical techniques, the labelling densities of chitin and -1,3- glucan in the cell wall of the fungicide-treated hyphae were decreased dramatically comparing with those of the control hyphae, indicating that the detrimental effects of the fungicide on structure and function of the hyphal membranes changes compositions of the cell walls.Maize species were evaluated for the resistance to the Curvularia leaf spot in seedling英文摘要and flowering stage after inoculation compared to Yedan13. The SSR results showed that there were differences in resistance level among species. Species Danyul3, Zhongdanl, Shandan911, Nongda60, Xinongll, Qin4 in seedling stage and species Xinong11, Shen10, Yu22, Danyu13, 7098 in flowering stage performed better resistance, respectively. Xinongl 1 and Danyu13 were resistant in both seedling and flowering stage.更多还原