环境地球化学国家重点实验室知识库

Metal-induced oxidative stress in contaminated soils affects plant growth.
In the present study, we evaluated the role of seed endophyte FXZ2 on
Dysphania ambrosioides Zn/Cd tolerance and accumulation. A series of pot
experiments were conducted under variable Zn (500, 1,000, and 1,500 mg
kg􀀀1) and Cd (5, 15, 30, and 60 mg kg􀀀1). The results demonstrated
that FXZ2-inoculation significantly enhanced the growth of D. ambrosioides
and improved its chlorophyll and GSH content. In the rhizosphere, FXZ2
inoculation changed the chemical speciation of Zn/Cd and thus affected their
uptake and accumulation in host plants. The exchangeable and carbonatebound
fractions (F1 + F2) of Zn decreased in the rhizosphere of FXZ2-
inoculated plants (E+) as compared to non-inoculated plants (E-) under
Zn stress (500 and 1,000 mg kg􀀀1), correspondingly, Zn in the shoots of
E+ decreased (p < 0.05). However, at Cd stress (30 and 60 mg kg􀀀1), the
F1 + F2 fractions of Cd in E+ rhizospheric soils increased; subsequently, Cd
in the shoots of E+ increased (p < 0.05). FXZ2 could exogenously secrete
phytohormones IAA, GA, and JA. The study suggests that seed endophyte
FXZ2 can increase Zn/Cd tolerance of host plant by altering Zn/Cd speciation
in rhizospheric soils, as well as exogenous production of phytohormones
to promote growth, lowering oxidative damage while enhancing antioxidant
properties. For Zn/Cd accumulation, it has opposite effects: Zn uptake in
E+ plants was significantly (p < 0.05) decreased, while Cd accumulation in
E+ plants was significantly (p < 0.05) increased. Thus, FXZ2 has excellent
application prospects in Cd phytoextraction and decreasing Zn toxicity in
agriculturally important crops.