花生(ArachishypogaeaL.)植物在其生长发育过程中对钙(Ca)有很高的要求,并具有从土壤中积累镉(Cd)的能力。然而,Ca和Cd之间拮抗作用的确切机制尚不清楚。本研究旨在通过将Ca与Cd的浓度比(CRCa/Cd)从250变化到3500来探索花生幼苗中Cd积累的动态变化。此外,通过分析Cd的化学形态,探讨了根中离子通道竞争和细胞壁固定对花生Cd积累的影响,亚细胞分布,果胶含量,和Cd2+通量使用非侵入式微测试技术(NMT)。结果表明,当CRCa/Cd高于2000时,花生幼苗中Cd的积累显着降低。在Ca预处理的幼苗(细胞壁固定处理)中,芽和根中Cd含量分别下降了18.9%和25.0%,分别,与同时暴露于Ca和Cd(离子通道竞争处理)相比。在Ca预处理组中,花生根中的Cd2流入量减少了55.8%。然而,在正常Ca条件下(>2mMCa),增加Ca2和Cd2的竞争强度不会影响Cd2的流入。同时,Ca预处理显著增加了Cd在根细胞壁中的分布,果胶,和蛋白质结合形式,同时显著降低了Cd在根系可溶性组分和无机Cd形态中的分布。在Ca和Cd同时暴露处理和Ca预处理中,根中果胶含量分别增加了128%和226%,分别。这些结果表明,Ca预处理可增强Cd在根细胞壁中的保留。总的来说,当CRCa/Cd低于2000时,外源Ca有效地减轻了花生植株中Cd的积累,Ca2通道部分促进了Cd2进入花生根中。在正常的Ca供应条件下,外源Ca主要通过根细胞壁固定而不是离子通道竞争来减少花生中Cd的积累。我们的发现为Ca减轻花生中Cd的吸收和转移的机制提供了见解。
Peanut (Arachis hypogaea L.) plant has a high requirement for calcium (Ca) during its growth and development, and possesses the ability to accumulate cadmium (Cd) from soil. However, the precise mechanisms underlying the antagonistic effects between Ca and Cd remain unclear. This study aimed to explore the dynamic changes in Cd accumulation in peanut seedlings by varying the Ca-to-Cd concentration ratio (CRCa/Cd) from 250 to 3500. Additionally, the influence of ion channel competition and cell wall fixation in the root on Cd accumulation in peanuts was explored by analyzing Cd chemical forms, subcellular distribution, pectin content, and Cd2+ fluxes using a non-invasive micro-test technique (
NMT). The findings revealed that Cd accumulation in peanut seedlings was significantly lower when the CRCa/Cd was higher than 2000. In the Ca-pretreated seedlings (cell wall fixation treatment), Cd content in the shoots and roots decreased by 18.9% and 25.0%, respectively, compared with the simultaneous exposure to Ca and Cd (ion channel competition treatment). Cd2+ influx in peanut roots decreased by 55.8% in the Ca-pretreated group. However, increasing the competitive strength of Ca2+ and Cd2+ did not affect Cd2+ influx under normal Ca conditions (>2 mM Ca). Meanwhile, Ca pretreatment significantly increased Cd distribution in the root cell wall, pectate, and protein-binding forms, while significantly reducing Cd distribution in root soluble components and inorganic Cd forms. The pectin content in the roots increased by 128% and 226% in the Ca and Cd simultaneous exposure treatment and Ca pretreatment, respectively. These results suggest that Ca pretreatment enhanced Cd retention in the root cell wall. Overall, exogenous Ca effectively mitigated Cd accumulation in peanut plants when the CRCa/Cd was below 2000, and Ca2+ channels partially facilitate the entry of Cd2+ into peanut roots. Under normal Ca supply conditions, exogenous Ca reduced Cd accumulation in peanuts primarily through root cell wall fixation rather than ion channel competition. Our findings provide insights into the mechanism by which Ca alleviates the uptake and transfer of Cd in peanuts.