黑腐病菌对抗感不同花椰菜品种叶片超微结构的影响

Effects of Xanthomonas campestris on the Ultrastructure of Leaf Tissue of Resistant and Susceptible Cauliflower Cultivars

为了从组织病理学角度探讨花椰菜对黑腐病菌的抗性机制,利用黑腐病菌(Xan-thomonas campestrispv.campestris)菌种BG02接种抗、感不同花椰菜(Brassica oleracea L. varbotrytis DC.)品种幼苗的第4片真叶,采用透射电镜技术观察研究黑腐病菌侵染的不同时期对花椰菜叶片细胞超微结构的影响。结果表明,黑腐病菌侵染后,花椰菜叶细胞的细胞壁变形、质壁分离、质膜断裂、叶绿体变形、片层结构零乱、线粒体膜破坏,甚至最后细胞器解体、膜系统破坏,直至整个细胞死亡。感病品种2003X-106的叶绿体片层和质膜部位受损害较早,叶绿体和线粒体外膜外突成致密的小球。抗病品种雪峰叶绿体膜系统比感病品种受损害时间晚且程度轻,近细胞壁处有电子密集物沉积。以上结果说明,黑腐病菌引起的细胞结构病变在抗、感品种间的表现不同,抗性品种叶片细胞的膜系统比感病品种的膜系统更能抵抗黑腐病菌的破坏。

In order to explore the histopathological resistance mechanism of cauliflowers to black rot（Xanthomonas campestris pv.campestris）,effect of black rot（BG02）infection on the ultrastructure of leaf tissue of resistant and susceptible cauliflowers cultivars（Brassica oleracea L.var botrytis DC.cv.Xuefeng and 2003X-106）were studied.The fourth true leaf was infected with pathogen BG02 through leaftip cut and then the ultrastructure of the leaf tissue was observed under transmission electron microscope.The results showed that after the black rot infection the host cell became plasma olyzed,cell walls and chloroplasts were deformed,chloroplasts lamellae became disordered,and the outer membrane of mitochondrion disorganized,even various organelles of the host cells collapsed,membrane systems were disrupted,which led to ultimate death of the host cells.The lamellae of chloroplasts and plasma membrane were more sensitive to the pathogen and their changes took place earlier.The damages on cell membranes of resistant cultivar Xuefeng were lighter and occurred later than that of susceptible cultivar 2003X-106.The accumulation of electron-opaque material nearby inner cell wall was observed in Xuefeng,whereas compact granulas formed from the outer membrane of chloroplasts and mitochondria were observed in 2003X-106.The results indicate that the cellular pathological changes to black rot were significantly different between resistant and susceptible varieties and membrane system from leaf cells of the resistant host had higher endurance ability than those from the susceptible one.