脯氨酸通过活性氧信号抑制植物生长

Proline inhibits plant growth by reactive oxygen species signaling

本研究采用具有不同脯氨酸浓度积累的3个拟南芥(Arabidopsis thaliana)株系——野生型(WT)、pdh突变体和脯氨酸脱氢酶基因(PDH)过量表达株系(PDH-S),通过检测其脯氨酸敏感性、H_2O_2含量和抗氧化酶活性的差异及WT中胁迫响应基因的表达情况,探讨脯氨酸抑制植物生长的原因。结果显示,脯氨酸敏感性以pdh突变体最高,WT居中,PDH-S最不敏感。脯氨酸处理后,植株体内的H_2O_2含量升高,PDH-S和WT相当且高于pdh突变体;抗氧化酶活性以PDH-S最高,pdh突变体最低。另外,脯氨酸处理能够诱导WT中胁迫响应基因的表达。研究表明,抑制植物生长的是脯氨酸自身而不是其代谢产物,脯氨酸可能通过活性氧信号途径对植物生长产生抑制作用。研究结果将有助于了解脯氨酸在植物生长发育和逆境恢复中的调节作用,为抗逆植物育种提供理论依据。

In order to explore the inner mechanism of the inhibiting effect, three different Arabidopsis lines, including wild type（WT）, pdh mutant（pdh） and proline dehydrogenase gene（PDH） over-expressed line（PDH-S）, with different concentrations of proline were used in this study. And the sensitivity of Arabidopsis lines to proline, H_2O_2 content and differences of antioxidant enzyme activities in Arabidopsis lines, as well as the expression of stress-responsive genes in WT line under proline stress were detected. Results showed that the sensitivity of three lines to proline presented as pdh WT PDH-S. H_2O_2 content was pdh WT = PDH-S, while antioxidant enzyme activities presented as PDH-S WT pdh after proline treatment. Moreover, stress-responsive genes were expressed under proline treatment in WT line. This study indicated that the inhibition to plants incurred by proline directly rather than its metabolites, and proline might inhibit plant growth by reactive oxygen species（ROS） signaling. This finding will be helpful to understand the role of proline in plant growth and recovery under stress condition, and provide a basis for plant breeding.