title: Diclofop-methyl affects microbial rhizosphere community and induces systemic acquired resistance in rice.
abstract: Diclofop-methyl (DM), a widely used herbicide in food crops, may partly contaminate the soil surface of natural ecosystems in agricultural area and exert toxic effects at low dose to nontarget plants. Even though rhizosphere microorganisms strongly interact with root cells, little is known regarding their potential modulating effect on herbicide toxicity in plants. Here we exposed rice seedlings (Xiushui 63) to 100μg/L DM for 2 to 8days and studied the effects of DM on rice rhizosphere microorganisms, rice systemic acquired resistance (SAR) and rice-microorganisms interactions. The results of metagenomic 16S rDNA Illumina tags show that DM increases bacterial biomass and affects their community structure in the rice rhizosphere. After DM treatment, the relative abundance of the bacterium genera Massilia and Anderseniella increased the most relative to the control. In parallel, malate and oxalate exudation by rice roots increased, potentially acting as a carbon source for several rhizosphere bacteria. Transcriptomic analyses suggest that DM induced SAR in rice seedlings through the salicylic acid (but not the jasmonic acid) signal pathway. This response to DM stress conferred resistance to infection by a pathogenic bacterium, but was not influenced by the presence of bacteria in the rhizosphere since SAR transcripts did not change significantly in xenic and axenic plant roots exposed to DM. The present study provides new insights on the response of rice and its associated microorganisms to DM stress.
authors.affiliation: Department of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310032, China. Electronic address: cslock@126.com.
authors.forename: Si
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Li
authors.affiliation: Quebec-Ocean and Takuvik Joint International Research Unit, Laval University, Quebec, G1V OA6, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Lavoie
authors.affiliation: College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Yujian
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Jiahui
authors.initials: J
authors.lastname: Xu
authors.affiliation: College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, China.
authors.forename: Zhengwei
authors.initials: Z
authors.lastname: Fu
authors.affiliation: College of Environment, Zhejiang University of Technology, Hangzhou 310032, China. Electronic address: hfqian@zjut.edu.cn.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Qian
mesh_terms: D000222:Adaptation, Physiological; D055768:Halogenated Diphenyl Ethers / Q000032:analysis / Q000633:toxicity*; D012275:Oryza / Q000502:physiology*; D058441:Rhizosphere; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis / Q000633:toxicity*
chemical_list: D055768:Halogenated Diphenyl Ethers; D012989:Soil Pollutants; C012891:dichlorfop-methyl
keywords: Diclofop-methyl; Organic acids; Rhizosphere microorganisms; Rice; Systemic acquired resistance