Barchet Genoa L H, Dauwe Rebecca, Guy Robert D, Schroeder William R, Soolanayakanahally Raju Y, Campbell Malcolm M, Mansfield Shawn D
Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4.
Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4 Present address: Faculty of Sciences, Plant Biology & Innovation Research Unit EA3900-UPJV, Université of Picardie Jules Verne, PRES UFECAP, Ilot des poulies, 33 rue Saint Leu, F-80039 Amiens Cedex, France.
Tree Physiol. 2014 Nov;34(11):1203-19. doi: 10.1093/treephys/tpt080. Epub 2013 Oct 31.
Drought stress is perhaps the most commonly encountered abiotic stress plants experience in the natural environment, and it is one of the most important factors limiting plant productivity. Here, we employed untargeted metabolite profiling to examine four drought-stressed hybrid poplar (Populus spp.) genotypes for their metabolite content, using gas chromatography coupled to mass spectrometry. The primary objective of these analyses was to characterize the metabolite profile of poplar trees to assess relative drought resistance and to investigate the underlying biochemical mechanisms employed by the genotypes to combat drought. Metabolite profiling identified key metabolites that increased or decreased in relative abundance upon exposure to drought stress. Overall, amino acids, the antioxidant phenolic compounds catechin and kaempferol, as well as the osmolytes raffinose and galactinol exhibited increased abundance under drought stress, whereas metabolites involved in photorespiration, redox regulation and carbon fixation showed decreased abundance under drought stress. One clone in particular, Okanese, displayed unique responses to the imposed drought conditions. This clone was found to have higher leaf water potential, but lower growth rate relative to the other clones tested. Okanese also had lower accumulation of osmolytes such as raffinose, galactinol and proline, but higher overall levels of antioxidants such as catechin and dehydroascorbic acid. As such, it was proposed that osmotic adjustment as a mechanism for drought avoidance in this clone is not as well developed in comparison with the other clones investigated in this study, and that a possible alternative mechanism for the enhanced drought avoidance displayed by Okanese may be due to differential allocation of resources or better retention of water.
干旱胁迫可能是植物在自然环境中最常遇到的非生物胁迫，也是限制植物生产力的最重要因素之一。在此，我们采用非靶向代谢物谱分析方法，利用气相色谱-质谱联用技术，检测了四种受干旱胁迫的杂交杨树（杨树属）基因型的代谢物含量。这些分析的主要目的是表征杨树的代谢物谱，以评估相对抗旱性，并研究这些基因型对抗干旱所采用的潜在生化机制。代谢物谱分析确定了在干旱胁迫下相对丰度增加或减少的关键代谢物。总体而言，氨基酸、抗氧化酚类化合物儿茶素和山奈酚，以及渗透调节物质棉子糖和半乳糖醇在干旱胁迫下丰度增加，而参与光呼吸、氧化还原调节和碳固定的代谢物在干旱胁迫下丰度降低。特别是一个名为奥卡内斯的无性系，对施加的干旱条件表现出独特的反应。相对于其他测试无性系，该无性系的叶水势较高，但生长速率较低。奥卡内斯的棉子糖、半乳糖醇和脯氨酸等渗透调节物质的积累也较低，但儿茶素和脱氢抗坏血酸等抗氧化剂的总体水平较高。因此，有人提出，与本研究中调查的其他无性系相比，该无性系中作为干旱规避机制的渗透调节发育不完善，奥卡内斯表现出的增强干旱规避的一种可能替代机制可能是由于资源分配差异或更好的水分保持。
