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Studies on Infectious Process of Plasmodiophora brassicae in Broccoli,Tomato and Pepper |
XIE Qi,LIU Yumei,HAN Fengqing,ZHUANG Mu,LI Zhansheng* |
Institute of Vegetables and Flowers,Chinese Academy of Agricultural Sciences,Key Laboratory of Horticultural Crop Biology and Germplasm Creation,Ministry of Agriculture and Rural Affairs,Beijing 100081,China |
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Abstract 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 bas is 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.
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Received: 20 August 2021
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