Allelochemical p-hydroxybenzoic acid inhibits root growth via regulating ROS accumulation in cucumber(Cucumis sativus L.)  

作　　者：HUANG Cheng-zhen XU Lei Sun Jin-jing ZHANG Zhong-hua FU Mei-lan TENG Hui-ying YI Ke-ke 

机构地区：[1]Key Laboratory of Plant Nutrition and Fertilizer,Ministry of Agriculture and Rural Affairs/Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agricultural Sciences,Beijing 10081,P.R.China [2]Key Laboratory of Biology and Genetic Improvement of Horticultural Crops of the Ministry of Agriculture,Sino-Dutch Joint Laboratory of Horticultural Genomics,Institute of Vegetables and Flowers,Chinese Academy of Agricultural Sciences,Beijing 10081,P.R.China [3]The Semi-arid Agriculture Engineering&Technology Research Center of China,Hebei 050051,P.R.China

出　　处：《Journal of Integrative Agriculture》2020年第2期518-527,共10页农业科学学报（英文版）

基　　金：supported by the National Key Research and Development Program of China (2018YFD1000803);the National Natural Science Foundation of China (31800246)

摘　　要：Allelopathy is prevalent in agricultural ecosystems and mediated by plant-derived secondary metabolites(allelochemicals).Allelochemicals are released by donor plants and affect the root growth and development of receptor plants.Allelopathy is responsible for the continuous cropping obstacles in cucumber(Cucumis sativus L.).p-Hydroxybenzoic acid(pHBA),an autotoxin from root exudates of cucumber,has been proposed to be an important allelopathic chemical.However,the molecular mechanism by which pHBA affect root growth and development in cucumber is unknown.Here,we found that pHBA treatment suppressed root growth of cucumber by reducing the meristem activity and cell length.This root growth defect is caused by reduced reactive oxygen species(ROS)accumulation in root tips.After pHBA treatment,the expression levels of several ROS-scavenging-related genes were increased,including peroxidase(POD),catalase(CAT)and metallothionein(MT).Moreover,exogenously application of salicylhydroxamate(SHAM),a peroxidase inhibitor,can partially restore the pHBA treatment induced root growth inhibition.Furthermore,we found that there is natural variation for the inhibitory effect of pHBA on root growth.We also showed that pHBA treatment could maintain higher level of ROS accumulated in the pHBA less sensitive cucumber than that in the pHBA-sensitive cucumber.These results suggest that pHBA inhibits root growth by reducing root tip ROS level in cucumber.Allelopathy is prevalent in agricultural ecosystems and mediated by plant-derived secondary metabolites(allelochemicals). Allelochemicals are released by donor plants and affect the root growth and development of receptor plants. Allelopathy is responsible for the continuous cropping obstacles in cucumber(Cucumis sativus L.). p-Hydroxybenzoic acid(pHBA), an autotoxin from root exudates of cucumber, has been proposed to be an important allelopathic chemical. However, the molecular mechanism by which pHBA affect root growth and development in cucumber is unknown. Here, we found that pHBA treatment suppressed root growth of cucumber by reducing the meristem activity and cell length. This root growth defect is caused by reduced reactive oxygen species(ROS) accumulation in root tips. After pHBA treatment, the expression levels of several ROS-scavenging-related genes were increased, including peroxidase(POD), catalase(CAT) and metallothionein(MT). Moreover, exogenously application of salicylhydroxamate(SHAM), a peroxidase inhibitor, can partially restore the pHBA treatment induced root growth inhibition. Furthermore, we found that there is natural variation for the inhibitory effect of pHBA on root growth. We also showed that pHBA treatment could maintain higher level of ROS accumulated in the pHBA less sensitive cucumber than that in the pHBA-sensitive cucumber. These results suggest that pHBA inhibits root growth by reducing root tip ROS level in cucumber.

关 键 词：ALLELOPATHY CUCUMBER reactive oxygen species natural variation 

分 类 号：S642.2[农业科学—蔬菜学]