Defez Roberto, Andreozzi Anna, Dickinson Michael, Charlton Adrian, Tadini Luca, Pesaresi Paolo, Bianco Carmen
Institute of Biosciences and BioResources - National Research Council, Naples, Italy.
Fera Science Ltd., National Agri-Food Innovation Campus, Sand Hutton, United Kingdom.
Front Microbiol. 2017 Dec 14;8:2466. doi: 10.3389/fmicb.2017.02466. eCollection 2017.
The drought-stress response in plant involves the cross-talk between abscisic acid (ABA) and other phytohormones, such as jasmonates and ethylene. The auxin indole-3-acetic acid (IAA) plays an integral part in plant adaptation to drought stress. Investigation was made to see how the main auxin IAA interacted with other plant hormones under water stress, applied through two different growth conditions (solid and hydroponic). plants nodulated by the wild type 1021 (-1021) and its IAA-overproducing RD64 derivative strains (Ms-RD64) were subjected to drought stress, comparing their response. When the expression of gene and the activity of the nitrogenase enzyme were measured after stress treatments, plants recorded a significantly weaker damage. These results were correlated with a lower biomass reduction, and a higher Rubisco protein level measured for the -stressed plants as compared to the -stressed ones. It has been verified that the stress response observed for -stressed plants was related to the production of greater amount of low-molecular-weight osmolytes, such as proline and pinitol, measured in these plants. For the plants the immunoblotting analysis of thylakoid membrane proteins showed that some of the photosystem proteins increased after the stress. An increased non-photochemical quenching after the stress was also observed for these plants. The reduced wilting signs observed for these plants were also connected to the significant down-regulation of the gene involved in the ABA biosynthesis, and with the unchanged expression of the two genes ( and ) of ABA signaling. When the expression level of the ethylene-signaling genes was evaluated by qPCR analysis no significant alteration of the key positive regulators was recorded for -stressed plants. Coherently, these plants accumulated 40% less ethylene as compared to -stressed ones. The results presented herein indicate that the variations in endogenous IAA levels, triggered by the overproduction of rhizobial IAA inside root nodules, positively affected drought stress response in nodulated alfalfa plants.
植物中的干旱胁迫响应涉及脱落酸（ABA）与其他植物激素（如茉莉酸酯和乙烯）之间的相互作用。生长素吲哚 - 3 - 乙酸（IAA）在植物适应干旱胁迫中起着不可或缺的作用。通过两种不同的生长条件（固体和水培）施加水分胁迫，研究了主要生长素IAA在水分胁迫下如何与其他植物激素相互作用。用野生型1021（-1021）及其IAA高产RD64衍生菌株（Ms - RD64）结瘤的植物遭受干旱胁迫，比较它们的响应。在胁迫处理后测量基因表达和固氮酶活性时，[此处原文缺失相关内容]植物记录到的损伤明显较弱。这些结果与较低的生物量减少相关，并且与胁迫植物相比，胁迫植物的Rubisco蛋白水平更高。已经证实，胁迫植物观察到的胁迫响应与这些植物中测量到的大量低分子量渗透物（如脯氨酸和松醇）的产生有关。对于[此处原文缺失相关内容]植物，类囊体膜蛋白的免疫印迹分析表明，一些光系统蛋白在胁迫后增加。这些植物在胁迫后还观察到非光化学猝灭增加。这些植物观察到的萎蔫迹象减少也与ABA生物合成相关基因的显著下调以及ABA信号传导的两个基因（[此处原文缺失相关内容]和[此处原文缺失相关内容]）的表达不变有关。当通过qPCR分析评估乙烯信号基因的表达水平时，胁迫植物的关键正向调节因子没有记录到显著变化。一致地，与胁迫植物相比，这些植物积累的乙烯减少了40％。本文给出的结果表明，根瘤内根瘤菌IAA过量产生引发的内源IAA水平变化对结瘤苜蓿植物的干旱胁迫响应产生了积极影响。
