镉胁迫对大豆细胞周期G2/M阻滞调控的影响

Effects of Cadmium Stress on Cell Cycle G2/M Arrest Regulation in Soybean

以镉抗性不同的2个大豆品种为试验材料,设置0、0.25、0.50和2.50 mg·L^(-1)4个镉浓度处理,研究幼苗根长形态指标、根尖细胞周期和相关基因的表达,旨在探讨镉胁迫对大豆细胞周期阻滞调控的影响,并筛选镉暴露对大豆细胞周期G2/M期阻滞的生物标志物.结果表明,不同的镉浓度暴露均能引起大豆幼苗根尖DNA的损伤,造成基因组的不稳定性,镉处理后辽豆10号细胞周期阻滞在G1/S期,而沈农豆20则是阻滞在G2/M期;DNA错配修复基因MSH2和MSH6的表达量与镉浓度呈明显倒U型剂量-效应关系;MMR系统的组成部分中MSH2和MSH6蛋白参与了大豆幼苗根尖镉胁迫诱导的G2期阻滞,并可作为镉诱导DNA损伤的直接传感器.同时MSH2和MSH6蛋白表达量的差异可以作为选育镉耐性大豆品种的指示生物标志物.

To investigate the effects of cadmium stress on cell cycle arrest regulation and screen the biomarkers of cadmium exposure to G2/M phase of cell cycle arrest in soybean(Glycine max),two soybean varieties with different cadmium resistance were used as experimental materials and four cadmium concentrations of 0,0.25,0.50,and 2.50 mg·L^(-1) were set to study the morphological index of seedling root length,root apical cell cycle,and expression of related genes.The results showed that different cadmium treatments could cause DNA damage in root tips of soybean seedling and lead to genomic instability.After cadmium treatment,cell cycle arrest of Liaodou 10 was in G1/S phase,while cell cycle arrest of Shennongdou 20 was in G2/M.The expression levels of DNA mismatch repair genes MSH2 and MSH6 showed an inverted U-shaped dosion-response relationship with cadmium concentration.MSH2 and MSH6 proteins,components of the MMR system,involved in the G2 phase arrest induced by cadmium stress in root tips of soybean seedling,and could be used as direct sensors of Cd-induced DNA damage.At the same time,the difference of MSH2 and MSH6 protein expression would be used as indicator biomarkers for breeding of cadmium soybean varieties.