瘤黑粉菌侵染对抗感玉米自交系苗期叶片的影响

Infection of Ustilago maydis between Resistant and Susceptible Leaves of Maize Inbred Line at Seedling Stage

玉米瘤黑粉病是我国玉米产区的主要病害之一,明确抗、感瘤黑粉病玉米自交系苗期感染瘤黑粉菌后的组织细胞、可溶性糖及保护性酶差异,是深入解析瘤黑粉病发生规律的基础和前提。以感病玉米自交系掖478和抗病自交系齐319为材料,播种后25d对幼苗进行人工接种瘤黑粉菌FB1×FB2,利用激光共聚焦显微镜、体视显微镜、扫描电镜和透射电镜观察接菌0,2,4,8,12d的叶片组织细胞结构差异。结果表明:掖478接菌后,菌丝快速增殖,通过叶肉细胞逐渐向维管束鞘细胞侵染,致使维管束鞘细胞叶绿体肿胀,淀粉粒增多,花环结构被破坏,最终形成瘤状物;齐319接菌后,菌丝增殖受抑制,组织细胞结构完整清晰,线粒体数量显著增加。通过分析接菌后不同时间节点抗、感玉米自交系叶片的可溶性糖含量和保护性酶活性差异,发现掖478可溶性糖含量逐渐上升,接菌后12d含量最高,齐319可溶性糖含量先升高后降低;抗、感玉米自交系的超氧化物歧化酶(SOD)活性均呈先升高后降低趋势,过氧化物酶(POD)和过氧化氢酶(CAT)活性均持续上升;且不同时间节点齐319保护性酶活性显著高于掖478。研究结果可为进一步揭示瘤黑粉病的侵染机制提供理论参考。

Common smut is one of the major diseases occurred on maize zone of China.It is the foundation and premise to identify the differences between resistant and susceptible tissues,cells,soluble sugar and defensive enzyme of maize inbred line at seedling stage.In this study,the susceptible inbred line Ye478 and resistant inbred line Qi319 were used as the materials,and Ustilago maydis fungi strain FB1×FB2 was artificially inoculated at 25-day-old seeding.The tissue and cell differences were investigated by using laser confocal microscope,stereoscopic microscope,scanning electron microscope,transmission electron microscope and the soluble sugar and defensive enzyme were been detected at 0d,2d,4d,8d and 12d after inoculation.The results showed that the hyphae rapidly proliferated and gradually infected vascular buldle sheath cells by mesophyll cells,which caused swelling,deformed and increased starch,and finally formed neoplasm in Ye478.In contrast,hyphae development had been inhibited,the cells structures were integral and clear but mitochondria increased significantly in Qi319.The content of soluble sugar gradually increased in Ye478 and peaked at 12d while it showed firstly increased and latter decreased in Qi319.The defensive enzyme activity of superoxide dismutase(SOD)increased early and then decreased while peroxidase(POD)and catalase(CAT)showed steady improvement in both inbred lines.Noticeably,the activity level of those three enzymes in Qi319 was higher than Ye478 at different time points.These results could provide theoretical reference for further revealing the infection mechanism of common smut.