酵母菌促进铅和镉胁迫下麻疯树生长的研究

为了筛选对铅和镉具有抗性和吸附性的酵母菌,构建麻疯树根系-酵母菌联合修复体系,促进高浓度铅和镉胁迫下麻疯树的生长。该研究分别从麻疯树的根段、珙桐的茎段、珙桐的根段分离到3株具有铅、镉抗性的酵母菌,分别命名为Jc、Di1、Di2,测定了三者对铅、镉的抗性和吸附性,并将筛选出的2株能吸附铅、镉的酵母菌菌株接种到麻疯树幼苗,研究接种两种酵母菌的麻疯树植株对铅、镉胁迫的响应。结果表明:经形态学和生理生化特征观察,Jc初步鉴定红酵母属(Rhodotorula sp.),Di1为假丝酵母属(Candida sp.),Di2为德巴利酵母属(Debaryomyces sp.)。三种酵母菌对铅、镉都有一定的抗性,其抗性能力的大小为JcDi2Di1。Di1和Jc对铅和镉都具有一定的吸附性将其用于接种麻疯树幼苗。与不接种酵母菌(CK)的麻疯树植株相比,接种Di1和Jc的麻疯树植株在根、茎、叶、全株干重方面显著增加,叶绿素、全株氮、全株磷浓度显著增加,SOD、POD、CAT的活性提高,丙二醛(MDA)浓度显著下降。从综合接种效应来看,Jc、Di1作为铅、镉的钝化剂,是铅、镉胁迫下促进麻疯树生长的备选菌株,这对于提高麻疯树对铅、镉污染土壤修复效率具有重要的意义。

Plant growth-promoting traits of yeasts on Jatrophacurcas under lead and cadmium stresses

In order to screen yeasts with resistance and adsorption to lead and cadmium, to construct a Jatropha curcas root-yeast phytoremediation system, and to promot the growth of J. curcas under high concentrations of lead and cadmium stresses, in this study, three endophytic yeasts with lead and cadmium resistance were isolated by surface-sterilized methods from the healthy J. curcas root, Davidia involucrata stem, D. involucrata root, named as Jc, Di1, Di2, respectively. The isolate were identified as Rhodotorula sp., Candida sp., Debaryomyces sp. based on morphologic, physiological and biochemical characteristics. They could grow on the PDA medium with a concentration of 500 mg·L^-1 Pb(NO₂)₂ or 50 mg·L^-1 CdCl₂·2.5 H₂O. Rhodotorula sp.(Jc)and Candida sp.(Di1)yeasts with adsorb ability of lead and cadmium were used to inoculate J. curcas seedling to study effects on the growth of J. curcas under cadmium and lead stresses; from morphological, biochemical and physiological characteristics, antioxidase of J. curcas plants inoculated yeasts under lead and cadmium stresses were also measured. The dry weights of J. curcas roots, shoots, leaves and whole plants showed a significant increase when the Rhodotorula sp.(Jc)and Candida sp.(Di1)yeasts were inoculated compared with non-inoculated CK plants. The plant growth-promoting effects of Rhodotorula sp. Jc and Candida sp. Di1 yeasts could be attributed to decreasing concentration of lead and cadmium in root, shoot and leaf; increasing activities of POD, SOD and CAT and concentration of chlorophyll, as well as concentration of nitrogen, phosphate in whole plant; and decreasing the concentration of malondialdehyde(MDA). Therefore, Rhodotorula sp.(Jc )and Candida sp.(Di1)yeasts may act as passivator of lead and cadmium to promote the growth of J. curcas under lead and cadmium stresses. This study is very important to improve phytoremediation efficiency of lead and cadmium contaminated soil by Jatropha curcas.