Abstract：
Exogenous abscisic acid (ABA) presents a novel approach to mitigate heavy metal (HM) accumulation in plants, yet its efficacy against multiple HMs and potential enhancement methods remain underexplored. In this study, we demonstrated that the exogenous ABA application simultaneously decreased Zn, Cd and Ni accumulation by 22-25 %, 27-39 % and 60-62 %, respectively, in wild-type (WT) Arabidopsis. Conversely, ABA reduced Pb in shoots but increased its root concentration. ABA application also modulated the expression of HM uptake genes, inhibiting IRT1, NRAMP1, NRAMP4, and HMA3, and increasing ZIP1 and ZIP4 expressions. Further analysis revealed that overexpressing the ABA-importing transporter (AIT1) in plants intensified the reduction of Cd, Zn, and Ni, compared to WT. However, the inhibitory effect of exogenous ABA on Pb accumulation was mitigated in shoots with higher AIT1 expression. Furthermore, HMs-induced growth inhibition and the damage to photosynthesis were also alleviated with ABA treatment. Conclusively, AIT1\'s synergistic effect with ABA effectively reduces Cd, Zn and Ni accumulation, offering a synergistic approach to mitigate HM stress in plants.
摘要：
外源脱落酸（ABA）提出了一种新的方法来减轻植物中重金属（HM）的积累，然而，其对多种HMs和潜在增强方法的疗效仍未得到充分探索。在这项研究中,我们证明了外源ABA的施用同时降低了Zn，Cd和Ni的累积量为22-25%，27-39%和60-62%，分别,在野生型（WT）拟南芥中。相反，ABA减少了芽中的Pb，但增加了其根浓度。ABA的应用还调节了HM摄取基因的表达，抑制IRT1、NRAMP1、NRAMP4和HMA3，并增加ZIP1和ZIP4的表达。进一步的分析表明，在植物中过量表达ABA输入转运蛋白（AIT1）会加剧Cd的减少，Zn,Ni,与WT相比。然而,在AIT1表达较高的芽中，外源ABA对Pb积累的抑制作用减弱。此外，ABA处理也减轻了HM诱导的生长抑制和对光合作用的损害。最后，AIT1与ABA的协同作用有效降低Cd,锌和镍的积累，提供了一种减轻植物HM胁迫的协同方法。
