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The transcription factor ZmbHLH105 confers cadmium tolerance by promoting abscisic acid biosynthesis in maize
Journal of Hazardous Materials ( IF 12.2 ) Pub Date : 2024-09-12 , DOI: 10.1016/j.jhazmat.2024.135826
Yazhou Meng 1 , Mengyao Li 1 , Ziting Guo 1 , Jiafa Chen 2 , Jianyu Wu 2 , Zongliang Xia 2
Affiliation  

Cadmium (Cd), a highly toxic heavy metal, profoundly impacts crop productivity. The bHLH-type transcription factors regulate plant stress responses, yet their involvement in maize's Cd stress response remains unclear. Here, we studied ZmbHLH105, a maize bHLH gene induced by Cd exposure. Overexpression of ZmbHLH105 in maize seedlings, which were treated with 1.0 mM CdCl2 for 7 days, increased endogenous ABA levels, decreased Cd accumulation, and enhanced Cd stress tolerance. ZmbHLH105 directly bound to promoter regions of two key ABA biosynthesis genes ZmNCED1/2, activating their transcription, thus boosting ABA levels and Cd tolerance. ZmbHLH105-overexpression promoted lignin synthesis, while ZmbHLH105-RNAi attenuated this effect. Exogenous ABA supplementation increased lignin content in Cd-stressed maize roots, suggesting ZmbHLH105-mediated Cd tolerance involves ABA-induced lignin deposition and cell wall thickening. Moreover, Cd transport-related gene expression was suppressed in ZmbHLH105 overexpression lines. Our findings demonstrate that ZmbHLH105 decreases Cd accumulation, improving Cd tolerance by enhancing ABA biosynthesis, increasing lignin deposition, thickening cell walls, and inhibiting Cd absorption in maize roots. This study unveils ZmbHLH105's mechanisms in Cd tolerance, highlighting its potential in breeding low Cd-accumulating crops for food and environment safety.

中文翻译:


转录因子 ZmbHLH105 通过促进玉米中脱落酸的生物合成赋予镉耐受性



镉 (Cd) 是一种剧毒的重金属,对农作物的产量产生深远影响。bHLH 型转录因子调节植物胁迫反应,但它们参与玉米的 Cd 胁迫反应仍不清楚。在这里,我们研究了 ZmbHLH105,一种由 Cd 暴露诱导的玉米 bHLH 基因。在玉米幼苗中过表达 ZmbHLH105,用 1.0 mM CdCl2 处理 7 d,增加内源性 ABA 水平,减少 Cd 积累,增强 Cd 胁迫耐受性。ZmbHLH105 直接与两个关键 ABA 生物合成基因 ZmNCED1/2 的启动子区结合,激活它们的转录,从而提高 ABA 水平和 Cd 耐受性。ZmbHLH105 过表达促进木质素合成,而 ZmbHLH105-RNAi 减弱了这种作用。外源 ABA 添加增加了 Cd 胁迫玉米根系的木质素含量,表明 ZmbHLH105 介导的 Cd 耐受性涉及 ABA 诱导的木质素沉积和细胞壁增厚。此外,ZmbHLH105 过表达系中 Cd 转运相关基因表达受到抑制。我们的研究结果表明,ZmbHLH105 通过增强 ABA 生物合成、增加木质素沉积、增厚细胞壁和抑制玉米根系对 Cd 的吸收来减少 Cd 积累、提高 Cd 耐受性。本研究揭示了 ZmbHLH105 在 Cd 耐受性中的机制,突出了其在培育低 Cd 积累作物以满足食品和环境安全方面的潜力。
更新日期:2024-09-12
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