Doctoral Program in Science of Natural Resources, Universidad de La Frontera, P.O. Box 54-D, Temuco, Chile.
Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
Plant Physiol Biochem. 2018 Mar;124:136-145. doi: 10.1016/j.plaphy.2018.01.010. Epub 2018 Jan 12.
Drought stress is the most important stress factor for plants, being the main cause of agricultural crop loss in the world. Plants have developed complex mechanisms for preventing water loss and oxidative stress such as synthesis of abscisic acid (ABA) and non-enzymatic antioxidant compounds such as anthocyanins, which might help plants to cope with abiotic stress as antioxidants and for scavenging reactive oxygen species. A. chilensis (Mol.) is a pioneer species, colonizing and growing on stressed and disturbed environments. In this research, an integrated analysis of secondary metabolism in Aristotelia chilensis was done to relate ABA effects on anthocyanins biosynthesis, by comparing between young and fully-expanded leaves under drought stress. Plants were subjected to drought stress for 20 days, and physiological, biochemical, and molecular analyses were performed. The relative growth rate and plant water status were reduced in stressed plants, with young leaves significantly more affected than fully-expanded leaves beginning from the 5th day of drought stress. A. chilensis plants increased their ABA and total anthocyanin content and showed upregulation of gene expression when they were subjected to severe drought (day 20), with these effects being higher in fully-expanded leaves. Multivariate analysis indicated a significant positive correlation between transcript levels for NCED1 (9-cis-epoxycarotenoid dioxygenase) and UFGT (UDP glucose: flavonoid-3-O-glucosyltransferase) with ABA and total anthocyanin, respectively. Thus, this research provides a more comprehensive analysis of the mechanisms that allow plants to cope with drought stress. This is highlighted by the differences between young and fully-expanded leaves, showing different sensibility to stress due to their ability to synthesize anthocyanins. In addition, this ability to synthesize different and high amounts of anthocyanins could be related to higher NCED1 and MYB expression and ABA levels, enhancing drought stress tolerance.
干旱胁迫是植物最重要的胁迫因素，是导致世界农业作物减产的主要原因。植物已经发展出复杂的机制来防止水分流失和氧化应激，例如合成脱落酸（ABA）和非酶抗氧化化合物，如花色苷，这可能有助于植物作为抗氧化剂应对非生物胁迫，并清除活性氧。A. chilensis (Mol.) 是一种先锋物种，在受胁迫和干扰的环境中定居和生长。在这项研究中，对 Aristotelia chilensis 的次生代谢进行了综合分析，以比较干旱胁迫下幼叶和完全展开叶中 ABA 对花色苷生物合成的影响。植物在干旱胁迫下处理 20 天，进行了生理、生化和分子分析。受胁迫植物的相对生长率和植物水分状况降低，幼叶在干旱胁迫的第 5 天开始比完全展开的叶片受影响更大。当 A. chilensis 植物受到严重干旱（第 20 天）时，它们会增加 ABA 和总花色苷含量，并上调基因表达，这些效应在完全展开的叶片中更高。多元分析表明，NCED1（9-顺式-环氧类胡萝卜素双加氧酶）和 UFGT（UDP 葡萄糖：黄酮-3-O-葡萄糖基转移酶）的转录水平与 ABA 和总花色苷之间存在显著的正相关。因此，这项研究提供了对植物应对干旱胁迫机制的更全面分析。幼叶和完全展开的叶片之间的差异突出了这一点，由于它们合成花色苷的能力，它们对胁迫表现出不同的敏感性。此外，合成不同和大量花色苷的能力可能与更高的 NCED1 和 MYB 表达和 ABA 水平有关，从而增强对干旱胁迫的耐受性。
