Integrative Network Analysis of Physiological, Transcriptomic, and Metabolomic Profiles Reveals the Mechanism of Propionic Acid-Mediated Alleviation of Cadmium Toxicity in Wheat (Triticum aestivum L.)

Cadmium (Cd), a pervasive toxic metal, poses significant
detrimental
effects on plant development and yield. Exogenous propionic acid (PA)
application significantly alleviated Cd toxicity in wheat seedlings.
Based on physiological analysis, exogenous 10 μM PA treatment
significantly reduced Cd accumulation by 36.29% in the shoot and 25.79%
in the root under 20 μM Cd treatment. Integrative transcriptomic
and metabolomic analyses revealed that PA enhances the antioxidant
capacity via activation of branched-chain amino acid (BCAA) metabolism
and salicylic acid (SA) signaling. Furthermore, PA upregulates TaHSP20 expression through H2O2 signaling,
promoting pectin synthesis and demethylation to improve Cd chelation
in the cell wall. Additionally, PA activates abscisic acid (ABA) signaling,
inducing the expression of TaHSP20 and TaHSP70 to reinforce cell wall biosynthesis and Cd sequestration. Key metabolites
such as sedoheptulose and rhamnose may further facilitate Cd2+ immobilization within the cell wall. These findings elucidate a
systemic mechanism underlying PA-mediated alleviation of Cd toxicity,
offering new strategies for improving agroecological sustainability.

镉（Cadmium, Cd）是一种广泛存在的有毒重金属，可对植物生长发育与产量造成显著的不利影响。外源丙酸（Propionic acid, PA）施用可显著缓解小麦幼苗所受的镉毒性。生理分析结果显示，在20 μM镉胁迫条件下，10 μM外源丙酸处理可使小麦地上部与根部的镉积累量分别降低36.29%与25.79%。整合转录组与代谢组分析表明，丙酸可通过激活支链氨基酸（Branched-chain amino acid, BCAA）代谢通路与水杨酸（Salicylic acid, SA）信号通路，增强植株的抗氧化能力。此外，丙酸可通过过氧化氢（H₂O₂）信号通路上调TaHSP20的表达，促进果胶合成与去甲基化，进而强化细胞壁对镉的螯合作用。同时，丙酸还可激活脱落酸（Abscisic acid, ABA）信号通路，诱导TaHSP20与TaHSP70的表达，增强细胞壁生物合成与镉固持过程。景天庚酮糖、鼠李糖等关键代谢物可进一步促进Cd²+在细胞壁中的固定。本研究阐明了丙酸介导缓解镉毒性的系统性调控机制，为提升农业生态可持续性提供了全新的研究策略。