Cadmium (Cd) is easily absorbed by rice and enters the food chain, posing a health risk to humans. Plant growth promoting bacteria (PGPB) can help the plant respond to Cd stress, but the mechanism of PGPB for Cd reduction is unclear. Therefore, this study was conducted and found inoculation with a newly isolated Pseudomonas koreensis promoted the growth of rice and reduced its Cd content. Fluorescent staining using PI and H2O2 probe indicated that PGPB attenuated oxidative damage in rice. Metabolomics revealed that 59 metabolites were upregulated after inoculation, with phenylpropanoids and flavonoids being significantly activated. Spectrophotometry analysis comfirmed the content of flavonoid, lignin, phenol, glutathione, proline and the activities of antioxidant enzymes were higher in the inoculated rice than in the control. Quantitative PCR showed the expression of genes related to phenylpropanoids (OsPAL, OsC4H, Os4CL) and flavonoids (OsCHS, OsCHI) was significantly increased by PGPB, while the genes of heavy metal transporters (OsNRAMP5, OsHMA2, OsIRT1) were significantly decreased. Overall, this study provides an insight into the PGPB-mediated detoxification mechanism in rice under Cd stress and emphasizes the role of phenylpropanoids and flavonoids in the production of low-Cd rice to ensure human health.

中文翻译：

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一种促进植物生长的细菌通过诱导苯丙烷和类黄酮的生物合成来支持水稻的镉解毒


镉 （Cd） 很容易被大米吸收并进入食物链，对人类健康构成风险。植物生长促进细菌 （PGPB） 可以帮助植物响应 Cd 胁迫，但 PGPB 减少 Cd 的机制尚不清楚。因此，进行这项研究，发现接种新分离的 Pseudomonas koreensis 促进了水稻的生长并降低了其 Cd 含量。使用 PI 和 H2O2 探针的荧光染色表明 PGPB 减轻了水稻的氧化损伤。代谢组学显示，接种后 59 种代谢物上调，其中苯丙烷类化合物和类黄酮被显著激活。分光光度法分析证实，接种水稻中黄酮、木质素、苯酚、谷胱甘肽、脯氨酸含量和抗氧化酶活性均高于对照。定量 PCR 显示 PGPB 显著增加苯丙烷类 （OsPAL， OsC4H， Os4CL） 和类黄酮 （OsCHS， OsCHI） 相关基因的表达，而重金属转运蛋白 （OsNRAMP5， OsHMA2， OsIRT1） 基因显著降低。总体而言，本研究对 Cd 胁迫下 PGPB 介导的水稻解毒机制提供了见解，并强调了苯丙烷类化合物和类黄酮在低 Cd 水稻生产中的作用，以确保人类健康。