title: Selenium inhibits root elongation by repressing the generation of endogenous hydrogen sulfide in Brassica rapa.
abstract: Selenium (Se) has been becoming an emerging pollutant causing severe phytotoxicity, which the biochemical mechanism is rarely known. Although hydrogen sulfide (H2S) has been suggested as an important exogenous regulator modulating plant physiological adaptions in response to heavy metal stress, whether and how the endogenous H2S regulates Se-induce phytotoxicity remains unclear. In this work, a self-developed specific fluorescent probe (WSP-1) was applied to track endogenous H2S in situ in the roots of Brassica rapa under Se(IV) stress. Se(IV)-induced root growth stunt was closely correlated with the inhibition of endogenous H2S generation in root tips. Se(IV) stress dampened the expression of most LCD and DCD homologues in the roots of B. rapa. By using various specific fluorescent probes for bio-imaging root tips in situ, we found that the increase in endogenous H2S by the application of H2S donor NaHS could significantly alleviate Se(IV)-induced reactive oxygen species (ROS) over-accumulation, oxidative impairment, and cell death in root tips, which further resulted in the recovery of root growth under Se(IV) stress. However, dampening the endogenous H2S could block the alleviated effect of NaHS on Se(IV)-induced phytotoxicity. Finally, the increase in endogenous H2S resulted in the enhancement of glutathione (GSH) in Se(IV)-treated roots, which may share the similar molecular mechanism for the dominant role of H2S in removing ROS by activating GSH biosynthesis in mammals. Altogether, these data provide the first direct evidences confirming the pivotal role of endogenous H2S in modulating Se(IV)-induced phytotoxicity in roots.
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Nanjing, China; Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Food Science, Henan Institute of Science and Technology, Xinxiang, Henan Province, China.
authors.forename: Hai-Zhen
authors.initials: HZ
authors.lastname: Mo
authors.affiliation: Lishui Plant Science Base, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
authors.forename: Mei-Yu
authors.initials: MY
authors.lastname: Zheng
authors.affiliation: Department of Chemistry, Washington State University, Pullman, Washington, United States of America.
authors.forename: Ming
authors.initials: M
authors.lastname: Xian
authors.affiliation: Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
authors.forename: Zhong-Qiang
authors.initials: ZQ
authors.lastname: Qi
authors.affiliation: Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
authors.forename: You-Qin
authors.initials: YQ
authors.lastname: Li
authors.affiliation: Department of Food Science, Henan Institute of Science and Technology, Xinxiang, Henan Province, China.
authors.forename: Liang-Bin
authors.initials: LB
authors.lastname: Hu
authors.affiliation: Institute of Food Quality and Safety, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Nanjing, China.
authors.forename: Li-Fei
authors.initials: LF
authors.lastname: Yang
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D029741:Brassica rapa / Q000187:drug effects / Q000254:growth & development*; D005978:Glutathione / Q000378:metabolism; D006862:Hydrogen Sulfide / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012643:Selenium / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D005978:Glutathione; D012643:Selenium; D006862:Hydrogen Sulfide