打开文本图片集
摘 要：为解析烟草对CMV的抗病细胞学机制，以抗病品种台烟8号和感病品种NC82为材料，利用透射电子显微镜对比两品种在接种CMV后发病过程中的细胞超微结构变化。结果表明：（1）接种CMV后，台烟8号发病症状多为花叶，NC82发病症状多泡斑和深绿、褪绿区域相间;（2）对比NC82轻微花叶和泡斑的超微结构发现，二者叶绿体类囊体片层都减少，但泡斑症状细胞内线粒体嵴和CMV颗粒密度都高于轻微花叶症状细胞，说明泡斑的细胞病变程度重于花叶症状;对比NC82和台烟8号的深绿和褪绿区域细胞超微结构发现，深绿区域的叶绿体形态较完整，而褪绿区域的叶绿体严重变形、类囊体片层紊乱、淀粉粒畸形或消失，说明褪绿区域叶肉细胞病变程度重于深绿区域;（3）对比所有病变叶片中过氧化物酶、自噬小体及内膜系统结构发现，台烟8号在CMV侵染后，其三者形态结构都比NC82的更规则有序。研究结果为进一步探究抗CMV烟草品种的抗性分子机制提供理论依据。
关键词：黄瓜花叶病;透射电子显微镜;超微结构;自噬
中图分类号：S435.72 文章编号：1007-5119（2019）03-0067-08 DOI：10.13496/j.issn.1007-5119.2019.03.010
Abstract： In order to reveal the cytological mechanism of tobacco resistance to CMV， we compared the ultrastructure of the leaves between resistant variety Taiyan 8 （T.T.8） and susceptible variety NC82 after CMV inoculation by transmission electronic microscopy （TEM）. The results showed that （1） After CMV infection， the disease symptoms of T.T.8 were mild mosaic， while that of NC82 often were bubble spot， light green island （LGI） and dark green island （DGI）. （2） Comparing the ultrastructure of mild mosaic and bubble spot in NC82， thylakoid lamellae of both symptoms were reduced， but the density of mitochondrial cristae and CMV coat particles in bubble spot cell was higher than that in slight mosaic. This indicated that the damage degree of cell structure of bubble spot was more severe than mild mosaic. Comparing the ultrastructure of LGI and DGI in NC82 and T.T.8， the structure of chloroplasts in DGI was integrated， while chloroplasts in LGI were seriously deformed， thylakoid lamellae was disordered， starch granules were abnormal or disappeared. It inferred that the degree of cell structure lesion in LGI was more serious than that in DGI. （3） Comparing to all pathological leaves， the morphology of autophagy structure， peroxisome and endomembrane system in T.T.8 were more orderly than NC82. The results from this study provide theoretical basis for further study on molecular resistance mechanisms of T.T.8.
Keywords： cucumber mosaic virus; transmission electronic microscopy （TEM）; ultrastructure; autophagy
黃瓜花叶病毒（Cucumber mosaic virus， CMV）病是危害烟草的主要病毒病之一，在烟草整个生育期都可以导致植株发病，严重影响烟叶的产质量及经济效益。通过解析烟草与CMV的互作机制，可为挖掘抗病基因、培育抗病品种提供理论依据，从而进一步推动抗CMV烟草品种的选育[1]。
烟草受CMV侵染后发病初期表现为明脉，随后发展成花叶、斑驳或泡斑，发病后期形成明显的深绿和褪绿区域[2]。通过细胞超微结构观察，CMV侵染会导致叶绿体结构肿胀、外膜破裂、内部片层松散，直至整个叶绿体解体[3]。而对于不同发病症状的叶肉细胞，其细胞超微结构有所不同，发病叶片的深绿区域细胞中叶绿体形态相对正常，类囊体数量较多且基粒堆叠紧密;而褪绿区域叶绿体中类囊体较少，基粒不完整且形态异常[4]。CMV侵染还会引起烟草其他细胞器的变化，如CMV侵染后诱导内质网应激，细胞器降解[5-6]。