Contribution of plant growth-promoting endophytic bacteria from hyperaccumulator to non-host plant zinc nutrition and health

Application of microbial agents is a novel strategy to improve the quality and health of plant, which can be used to increase zinc (Zn) uptake and alleviate Zn toxicity. Here, endophytic bacteria with Zn solubilizing and growth-promoting properties were isolated from hyperaccumulating ecotype (HE) of <i>Sedum alfredii</i> Hance and their effects on Zn absorption and accumulation of non-hyperaccumulating ecotype (NHE) were studied. The results showed that most endophytic bacteria of HE have good Zn solubilizing or growth-promoting properties. Under the condition of 20 μM ZnSO₄, the biomass of NHE inoculated with SaPS1, SaEN2, SaPR2, SaBA2, SaBA3 was 2.8-3.2 times higher than that of non-inoculation control, and the Zn concentration of shoots was increased by 45.9, 89.0, 53.7, 77.5, and 42.6% after inoculation with SaPA1, SaP1, SaEN2, SaBA1, and SaBA2. Under the condition of 100 μM ZnSO₄, inoculation with SaVA1, SaPS3, SaB1, SaPR1, and SaEN3 alleviated Zn stress and significantly reduced Zn concentration of shoots. Therefore, endophytic bacteria can be an effective means of improving plant Zn nutrition quality in the normal condition and benefit plant health in the stress environment.