过氧化氢参与拟南芥根部避盐调控

Hydrogen peroxide is involved in the regulation of root Halotropism in Arabidopsis thaliana

已有研究发现植物通过调整根部向地性避开高浓度盐离子富集的区域,进而提高植物耐盐性(Halotropism),然而调控植物Halotropism机制尚不清楚。H 2O 2被认为是植物响应盐胁迫的关键信号分子,为探索H 2O 2在Halotropism中的潜在调控作用,文章采用2个H 2O 2水平增强突变体 cat2和apx1作为遗传材料进行相关分析。发现与野生型相比,cat2和apx1 突变体加速Halotropism现象的出现,暗示H 2O 2有利于根部避盐。进一步观察发现 cat2 体内的生长素信号明显低于Col-0水平,进一步证实H 2O 2可能是连接植物盐信号与Halotropism现象的中间介导子,并且可能与调控生长素信号有关。此外,文章还分析了重金属离子胁迫(汞和镉)对拟南芥根部向地性的影响,发现拟南芥在汞或镉处理的条件下不会发生像NaCl胁迫诱导的Halotropism现象。

It is reported that plant roots are able to modify their direction of growth to escape the high salt-containing media, and subsequently improve their salt tolerance(named as Halotropism). However, the regulatory mechanism is still unclear. H 2O 2 is believed to act as a key signal molecule to mediate the response of the plant to salt stress. To explore the potential role of H 2O 2 in the regulation of Halotropism, two genetic mutants cat2 and apx1 where H 2O 2 level accumulated more than that of Col-0 were utilized. It was shown that both mutants triggered Halotropism faster compared with the wild type. This suggested that H 2O 2 was a component to involve Halotropism. Furthermore, it was found that the level of auxin in cat2 was significantly lower than the Col-0 level by confocal analysis. The result further revealed that H 2O 2 was a linker between salt signal and Halotropism in an auxin-associated manner. In addition, the effect of heavy metal stress(mercury and cadmium) on the geotropism in Arabidopsis thaliana was analyzed, and it was found that unlike salt induced Halotropism, such effect did not occur in the presence of either mercury or cadmium.