秦冠苹果品种对苹果黑星病的组织学抗性研究

Histocytological study of“Qinguan”cultivar resistant to apple scab

为揭示苹果抗病品种秦冠在组织细胞学水平上抗苹果黑星病的特征,本研究采用扫描和透射电镜技术,将苹果黑星菌Venturia inaequalis接种侵染寄主后,系统观察抗病品种秦冠和感病品种嘎啦的叶片组织和细胞结构变化。扫描电镜观察结果表明,黑星菌分生孢子悬浮液接种秦冠和嘎啦叶片48 h后,病菌沿叶脉生长扩展,其菌丝可从叶片气孔或直接侵入。透射电镜观察结果表明,秦冠叶片的角质层厚度明显高于嘎啦,其中秦冠角质层平均厚度为1.75μm,嘎啦为1.06μm。透射电镜观察结果表明,黑星菌菌丝在寄主叶肉细胞间扩展,导致嘎啦栅栏组织细胞萎缩,排列松散,叶绿体变形受损,细胞内出现较大淀粉粒和胞内物质外渗流失,并在后期发展成大量细胞坏死;而秦冠虽症状类似,但受损程度明显小于嘎啦。以上结果表明,秦冠在组织细胞学上对苹果黑星病具有抗侵染、抗扩展和延缓病程发展的作用,可作为苹果黑星病抗性育种材料加以利用。

In order to reveal the characteristics of resistance to apple scab at the level of histocytology,the changes of leaf tissue and cell structure of apple resistant cultivar“Qinguan”and susceptible cultivar“Gala”were systematically observed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)after inoculating the hosts with conidial suspension of Venturia inaequalis.The results of SEM observation showed that hypha of pathogen grew and expanded along the veins of host leaf in 48 hours after inoculation,and invaded into leaf tissue directly or from stomata.TEM observation showed that the leaf cuticle thickness of“Qinguan”was significantly thicker than that of“Gala”,and the average cuticle thickness of“Qinguan”was 1.75μm while that of“Gala”was 1.06μm.It was observed that the hyphae of Venturia inaequalis expanded intercellularly in the mesophyll resulting in palisade cells shrank,loosely arranged,decreased in number,and the chloroplasts were deformed and thereby seriously damaged the cultivar“Gala”.Large starch granules appeared and intracellular substances leaked out,resulting in seriously cell necrosis in the later stage.A similar phenomenon also occurred in“Qinguan”,but the degree of cells damage was obviously alleviated.The research results indicated the cultivar“Qinguan”was able to resist to pathogen’s penetration and extension and delay the development of scab pathogenesis,and hopefully can be used as scab-resistant breeding material.