青花菜、番茄与辣椒根肿菌侵染过程研究

Studies on Infectious Process of Plasmodiophora brassicae in Broccoli,Tomato and Pepper

为了明确十字花科与茄果类蔬菜作物根肿菌侵染根细胞的变化特征,本试验选取十字花科蔬菜青花菜品种中青10号和中青16号(感病组),番茄品种中杂302和辣椒品种中椒115(对照组)进行比较试验,通过对两组试验对象进行根部染色及细胞学观察,揭示青花菜、番茄和辣椒在根肿菌侵染过程中的根部特征和差异变化。分子辅助鉴定结果表明,供试菌株(河南新野)为4号生理小种。以水培法培育青花菜、番茄和辣椒幼苗,在根肿菌接种后14 d内,根肿菌侵染途径基本一致:根肿菌最先进入3种蔬菜作物的根毛区,然后继续侵入根部皮层细胞,形成分生孢子或孢子囊。在根肿菌侵染率方面,青花菜与番茄、辣椒存在明显差异:根肿菌在接种后7 d和14 d能够快速侵染青花菜,并在14 d时的皮层细胞内形成大量的分生孢子和孢子囊;根肿菌侵染番茄的速率明显低于青花菜,且根肿菌侵染数量明显减少,仅在根毛区形成分生孢子,能侵染皮层细胞但不能形成孢子囊;辣椒根毛区根肿菌侵染速率最慢,且根肿菌侵染效率最低,只在根毛区形成少量的分生孢子,极少数孢子能进入皮层细胞,但不能形成孢子囊。本试验揭示了我国主要根肿病致病菌(4号生理小种)在水培环境下侵染青花菜、番茄和辣椒的变化特征,为科学解释茄果类蔬菜抗根肿病机理提供了依据,也为创制十字花科抗根肿病种质开辟了一条新途径。

In order to clarify the change features of root cells in cruciferous and solanaceous vegetables infected by Plasmodiophora brassicae,this experiment selected 2 broccoli varieties‘Zhongqing No.10’,‘Zhongqing No.16’(susceptible group),tomato variety‘Zhongza 302’and pepper variety‘Zhongjiao 115’(control group);and conducted a comparative test.Cytological observation after root staining of these 2 groups was carried out to reveal the root characteristics and changes of broccoli,tomato and pepper during the infection process by Plasmodiophora brassicae.Results of molecular-assisted identification showed that the tested strain was physiological race No.4.The infection pathway of Plasmodiophora brassicae in broccoli,tomato and pepper seedlings cultivated by hydroponics was basically the same within 14 days after inoculation of Plasmodiophora brassicae.Plasmodiophora brassicae firstly entered into the root-hair zone of these 3 vegetable crops,then continued to invade the root cortical cells and to form conidium or sporangium.In terms of the infection rate of Plasmodiophora brassicae,broccoli was significantly different from tomato and pepper.Plasmodiophora brassicae could quickly infect broccoli 7 and 14 days after inoculation,and a large number of conidia and sporangia were formed in the cortical cells 14 days after inoculation.The infection rate of Plasmodiophora brassicae in tomato was obviously lower than that in broccoli,and the infection quantity of Plasmodiophora brassicae was significantly reduced.The conidia could be formed only in root-hair zone and infect cortical cells,but sporangia could not be formed.The infection rate of Plasmodiophora brassicae in pepper in root-hair zone was the slowest,and its infection efficiency was the lowest.Only a small amount of conidia was formed in root-hair zone,and a very few conidia could enter into the cortical cells,but no sporangia was formed.This study revealed the change features of dominant pathogen of clubroot(physiological race No.4)infecting broccoli,tomato,and pepper in hydroponic environment;thus providing a basis for scientifical explanation of clubroot resistance mechanism in solanaceous vegetables,and also opening up a new pathway for creation of germplasm resistant to clubroot in cruciferous crops.