Savouré A, Hua X J, Bertauche N, Van Montagu M, Verbruggen N
Department of Genetics, Flanders Interuniversity Institute for Biotechnology (VIB), Universiteit Gent, Belgium.
Mol Gen Genet. 1997 Mar 18;254(1):104-9. doi: 10.1007/s004380050397.
The role of the phytohormone abscisic acid (ABA) in the regulation of proline synthesis was investigated by following the expression of the At-P5S and At-P5R proline biosynthesis genes in Arabidopsis thaliana wild type, in an ABA-deficient aba1-1 mutant as well as in ABA-insensitive abi1-1 and abi2-1 mutants after ABA, cold and osmotic stress treatments. In wild-type and in ABA mutant seedlings, 50 microM ABA or osmotic stress treatment triggered expression of At-P5S, whereas At-P5R accumulation was scarcely detectable. Expression of either gene was mediated by endogenous ABA since transcript levels were similar in wild-type and in ABA-deficient mutant plants. Proline accumulated to a greater extent after osmotic stress than upon ABA or cold treatment. Thus, ABA-treated abi1-1 mutant plants accumulated less proline than the ABA-treated wild type. Upon salt stress, proline accumulated to a lesser extent in aba1-1 and abi1-1 mutant plants, suggesting an indirect role of ABA on proline accumulation during salt adaptation of the plant. These results indicate that the expression of the genes of the proline biosynthetic pathway is ABA independent upon cold and osmotic treatments, although their expression can be triggered by exogenously applied ABA. However, the endogenous ABA content may affect proline accumulation upon salt stress, suggesting post-transcriptional control of proline biosynthesis in response to NaCl.
通过追踪拟南芥野生型、ABA缺陷型aba1-1突变体以及ABA不敏感型abi1-1和abi2-1突变体在ABA、低温和渗透胁迫处理后脯氨酸生物合成基因At-P5S和At-P5R的表达情况，研究了植物激素脱落酸（ABA）在脯氨酸合成调控中的作用。在野生型和ABA突变体幼苗中，50微摩尔ABA或渗透胁迫处理可触发At-P5S的表达，而At-P5R的积累几乎检测不到。由于野生型和ABA缺陷型突变体植物中的转录水平相似，因此这两个基因的表达均由内源性ABA介导。渗透胁迫后脯氨酸的积累程度比ABA或低温处理后更大。因此，ABA处理的abi1-1突变体植物积累的脯氨酸比ABA处理的野生型少。在盐胁迫下，aba1-1和abi1-1突变体植物中脯氨酸的积累程度较低，这表明ABA在植物盐适应过程中对脯氨酸积累起间接作用。这些结果表明，脯氨酸生物合成途径基因的表达在低温和渗透处理时不依赖ABA，尽管外源施加ABA可触发它们的表达。然而，内源性ABA含量可能会影响盐胁迫下脯氨酸的积累，这表明脯氨酸生物合成在响应NaCl时存在转录后调控。
