| S-烯丙基-L-半胱氨酸缓解水稻种子幼根和幼芽镉胁迫机制 |
| 摘要点击 2021 全文点击 624 投稿时间：2020-10-21 修订日期：2020-11-24 |
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| 中文关键词 S-烯丙基-L-半胱氨酸(SAC) 水稻 Cd胁迫 镉转运基因 种子萌发 |
| 英文关键词 S-allyl-L-cysteine (SAC) rice Cd stress cadmium transporter gene seed germination |
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| 中文摘要 |
| 土壤Cd污染对水稻种子萌发和植株生长发育都具有毒害作用，最终可能导致稻谷产量下降及Cd含量超标.本文采用种子萌发试验研究了来源于大蒜提取物的天然含硫有机化合物S-烯丙基-L-半胱氨酸（SAC）缓解水稻种子幼根和幼芽Cd2+胁迫的潜在机制.本试验过程中选用我国南方稻区主栽水稻品种"中早35"种子作为试验材料，首先研究了SAC对水稻种子幼根和幼芽Cd2+胁迫的缓解效应；在此基础上，通过研究SAC对种子幼根和幼芽生理生化系统及Cd含量影响，探索了SAC缓解水稻种子幼根和幼芽Cd2+胁迫的生理机制；利用实时荧光定量PCR技术研究了SAC对水稻Cd转运蛋白编码基因表达水平的影响，探讨了SAC缓解Cd2+胁迫的分子机制.结果表明，当Cd2+胁迫浓度达到50 μmol·L-1时水稻种子幼根和幼芽发育会受到显著抑制；当SAC添加浓度达到200 μmol·L-1时，幼根的总根长、根表面积和根体积与50 μmol·L-1Cd2+胁迫处理组相比分别增加173.5%、65.52%和37.04%；幼根和幼芽中CAT、SOD活性分别增加212.42%、110.76%和31.41%、47.31%；幼根和幼芽中MDA、GSH含量分别降低43.09%、34.12%和33.97%、35.74%；幼根和幼芽中Cd含量分别降低35.91%、28.86%.实时荧光定量PCR分析结果表明，添加SAC处理后Cd转运蛋白编码基因OsNramp5和OsHMA2的相对表达量与Cd2+胁迫处理组相比分别显著降低了33.38%和34.99%，OsHMA3的相对表达量与Cd2+胁迫处理组相比显著升高了33.96%.由以上试验结果可见，SAC降低水稻幼根和幼芽Cd2+胁迫的主要机制是SAC调控了Cd转运蛋白编码基因的表达水平，降低了Cd向幼根和幼芽中的转运，同时增加了Cd向液泡中的转运. |
| 英文摘要 |
| Cd has toxic effects on rice seed germination and plant growth, which may eventually lead to decreased yield and excessive Cd content in rice grains. The potential mechanism of S-allyl-L-cysteine (SAC), a natural sulfur compound derived from garlic extract, in alleviating Cd2+ stress in young roots and buds of rice seedlings was studied by a seed germination experiment. "Zhong zao 35", one of the main rice varieties in Southern China, was selected as the test material. Firstly, the alleviating effect of SAC on Cd2+ stress in rice seedling roots and buds was studied. Following this, the physiological mechanism of Cd2+ stress alleviation by SAC was examined based on the expression of the Cd transporter coding gene using real-time fluorescent quantitative PCR. The results showed that when the Cd2+ stress concentration reached 50 μmol·L-1, the young roots and buds of rice seedlings were significantly inhibited, and when the SAC concentration reached 200 μmol·L-1, Cd2+ stress was significantly alleviated. Compared to a Cd2+ stress treatment group, the total root length, surface area, and volume of young roots was increased by 173.5%, 65.52%, and 37.04%, respectively; CAT and SOD activity in young roots and buds was increased by 212.42% and 110.76%, and 31.41% and 47.31%, respectively; MDA and GSH content was decreased by 43.09% and 34.12%, and 33.97% and 35.74%, respectively; and Cd content was decreased by 35.91% and 28.86%, respectively. The results of quantitative real-time PCR showed that the relative expression levels of OsNramp5 and OsHMA2 were significantly reduced by 33.38% and 34.99% compared with the Cd2+ stress group, respectively. However, the relative expression level of OsHMA3 was significantly increased by 33.96%. From the above experimental results, the main mechanism by which SAC reduces Cd2+ stress in the young roots and buds of rice is via the regulation of Cd transporter-encoding genes, reducing Cd2+ transport to young roots and buds, and increasing transport to vacuoles. |
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