College of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China; ZheJiang Zone-King Environmental Sci & Tech Co., Ltd., Hangzhou 310064, China.
Planting Technology Extension Center of Dongyang, Jinhua 322100, China.
J Hazard Mater. 2022 Oct 15;440:129769. doi: 10.1016/j.jhazmat.2022.129769. Epub 2022 Aug 13.
Exogenous abscisic acid (ABA) could inhibit cadmium (Cd) accumulation in plants; however, its performance in an uneven iron (Fe) background remains unknown. Here, we found that the inhibitory effects of ABA on Cd accumulation in plants were optimal under nonlimiting Fe availability (25 and 50 µM), causing a reduction of 25-50 %, whereas only a 0-29 % decrease was observed in a Fe-free or -deficient (5 µM) medium. Although ABA significantly inhibited the expression of IRT1 under different Fe supplies, the inhibitory effects of ABA on Cd accumulation were lower (or absent) in irt1-mutants than in wild-type plants growing under nonlimiting Fe availability, whereas no significant difference was found under Fe deficiency. The mechanisms by which ABA reduces Cd accumulation under different Fe environments may differ. Furthermore, under Fe sufficiency, ABA increased Fe levels of root apoplasts by 91 % without changing the activity level of root ferric reductase (FCR). In contrast, ABA resulted in a 17 % decrease in Fe concentration in apoplasts and a 37 % decrease in FCR activity under Fe-deficient conditions. Thus, under Fe sufficiency, plants may show a reduced accumulation of Cd by accumulating more Fe in the apoplasts, which in turn inhibits the expression of IRT1. However, plants are more prone to redirect apoplastic Fe to prevent Cd accumulation under Fe deficiency. The different mechanisms of inhibition of Cd accumulation by ABA under different Fe supplies revealed in this study may provide guidelines for the precise regulation of Cd accumulation in crops via ABA-based strategies.
外源脱落酸（ABA）可以抑制植物中镉（Cd）的积累；然而，其在不均匀铁（Fe）背景下的表现尚不清楚。在这里，我们发现 ABA 对植物中 Cd 积累的抑制作用在非限制 Fe 可利用性（25 和 50 µM）下最佳，导致减少 25-50%，而在无 Fe 或 Fe 缺乏（5 µM）培养基中仅观察到 0-29%的减少。尽管 ABA 在不同的 Fe 供应下显著抑制了 IRT1 的表达，但在非限制 Fe 可利用性下生长的 ir t1 突变体中，ABA 对 Cd 积累的抑制作用低于（或不存在）野生型植物，而在 Fe 缺乏下则没有发现显著差异。ABA 在不同 Fe 环境下降低 Cd 积累的机制可能不同。此外，在 Fe 充足的情况下，ABA 将根质外体的 Fe 水平增加了 91%，而没有改变根铁还原酶（FCR）的活性水平。相比之下，在 Fe 缺乏的情况下，ABA 导致质外体中 Fe 浓度降低 17%，FCR 活性降低 37%。因此，在 Fe 充足的情况下，植物可能通过在质外体中积累更多的 Fe 来减少 Cd 的积累，从而抑制 IRT1 的表达。然而，在 Fe 缺乏的情况下，植物更倾向于将质外体中的 Fe 重新引导到根部以防止 Cd 积累。本研究揭示了 ABA 在不同 Fe 供应下抑制 Cd 积累的不同机制，可为通过 ABA 策略精确调控作物中 Cd 积累提供指导。
