Ruđer Bošković Institute, P.O.Box 180, HR-10002 Zagreb, Croatia.
Plant Cell Rep. 2013 Jul;32(7):1031-42. doi: 10.1007/s00299-013-1412-7. Epub 2013 Mar 19.
Stress hormones, particularly jasmonic acid, influenced root growth, auxin levels, and transcription of auxin amidohydrolase BrIAR3 in Brassica rapa seedlings, while auxin conjugate synthetases BrGH3.1 and BrGH3.9 were down-regulated by all treatments. The influence of stress hormones: jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA) on 1-day-old seedlings of Chinese cabbage (Brassica rapa L. ssp. pekinensis) was investigated with particular focus on auxin levels and the regulation of reversible auxin conjugation as a mechanism of auxin homeostasis. At the physiological level, stress hormones inhibited root growth, where JA was the most prominent inhibitor with an IC50 value 3.1 μM, which is one and two orders of magnitude lower than that found for ABA and SA, respectively. JA treatment significantly increased the total auxin content, by induction of free and conjugated forms. Also, the stress hormones affected the transcription of genes involved in the process of the reversible auxin conjugation: auxin amidohydrolases BrIAR3 and BrILL2, and auxin conjugate synthetases BrGH3.1 and BrGH3.9. JA treatment increased the transcript level of BrIAR3 two-fold, while it did not affect the transcription of BrILL2. SA and ABA down-regulated the transcription of both auxin amidohydrolase genes by 30 %. Transcription of both auxin conjugate synthetases was significantly down-regulated by all treatments by 30-70 %. Among the investigated biochemical stress markers, glutathione along with protein carbonylation appeared the most affected upon treatments. The redox status of the seedlings was shifted to the more oxidized state upon JA and ABA treatments, whereas SA caused more reduced redox state in comparison to the control. The principal component analysis visualized relationship among auxin and stress parameters upon treatments. Accordingly, the role of auxin in stress response of Brassica seedlings was discussed.
应激激素，特别是茉莉酸，影响了油菜幼苗的根生长、生长素水平以及生长素酰胺水解酶 BrIAR3 的转录，而生长素结合物合成酶 BrGH3.1 和 BrGH3.9 则被所有处理下调。应激激素：茉莉酸（JA）、水杨酸（SA）和脱落酸（ABA）对白菜（ Brassica rapa L. ssp. pekinensis）1 日龄幼苗的影响，特别关注生长素水平和可逆的生长素结合作为生长素稳态的调节机制。在生理水平上，应激激素抑制根生长，其中 JA 是最显著的抑制剂，IC50 值为 3.1 μM，分别比 ABA 和 SA 低一个和两个数量级。JA 处理显著增加了游离和结合形式的总生长素含量。此外，应激激素还影响参与可逆生长素结合过程的基因的转录：生长素酰胺水解酶 BrIAR3 和 BrILL2，以及生长素结合物合成酶 BrGH3.1 和 BrGH3.9。JA 处理使 BrIAR3 的转录水平增加了两倍，而对 BrILL2 的转录没有影响。SA 和 ABA 使两种生长素酰胺水解酶基因的转录分别下调了 30%。所有处理均使两种生长素结合物合成酶的转录显著下调了 30-70%。在所研究的生化应激标志物中，谷胱甘肽和蛋白质羰基化似乎受处理影响最大。JA 和 ABA 处理使幼苗的氧化还原状态向更氧化的状态转变，而 SA 处理使氧化还原状态比对照更还原。主成分分析可视化了处理后生长素和应激参数之间的关系。因此，讨论了生长素在油菜幼苗应激反应中的作用。
