生长素信号转导途径与植物胁迫反应相互作用的证据

生长素影响植物多种生理过程,有报道显示生长素可能影响植物对逆境胁迫的反应.我们利用cDNA阵列技术鉴定拟南芥(Arabidopsis thaliana (L.) Heynh.)的生长素应答基因,发现多个胁迫应答基因受生长素抑制,包括Arabidopsis homolog of MEK kinase1 (ATMEKK1),RelA/SpoT homolog 3 (At-RSH3),Catalase 1 (Cat1) 和Ferritin 1 (Fer1),说明生长素可调节胁迫应答基因的表达.此外,我们还证明吲哚乙酸(IAA)合成途径中的腈水解酶基因nitrilase 1 (NIT1) 和nitrilase 2 (NIT2) 受盐胁迫诱导,提示在逆境条件下IAA的合成可能随之增加.我们利用生长素不敏感突变体研究生长素与逆境反应相互作用的信号转导,发现胁迫应答基因在野生型和生长素不敏感突变体auxin resistant 2 (axr2) 中可被盐胁迫诱导,而在auxin resistant 1-3 (axr1-3)中则不被诱导,说明生长素与逆境胁迫反应的相互作用可能发生在泛素途径.

Evidence That the Auxin Signaling Pathway Interacts with Plant Stress Response

Auxin influences a variety of developmental and physiological processes. Early reports suggested that auxin might affect plant stress response. We have identified a number of auxin responsive genes in Arabidopsis thaliana (L.) Heynh. by using cDNA array and found that stress responsive genes, such as Arabidopsis homolog of MEK kinase 1 (ATMEKK1), RelA/SpoT homolog 3 (At-RSH3), Catalase 1 (Cat1) and Ferritin 1 (Fer1),were down regulated by auxin, indicating that auxin regulates the expression of stress responsive genes. We also demonstrated that nitrilase genes, nitrilase 1 (NIT1) and nitrilase 2(NIT2) involving in indole 3 acetic acid (IAA) biosynthesis, were induced by salinity stress, suggesting that the level of IAA might increase in response to salinity stress. To dissect the signal pathway involved in the interaction, two auxin insensitive mutants, auxin resistant 2 (axr2) and auxin resistant 1-3 (axr1-3) were used. Stress responsive genes were induced by salt stress in wild type and axr2, but not in axr1 3. The result suggests that the interaction between auxin and stress responses may be linked in the ubiquitin pathway.