Natural Resources Institute Finland (Luke), Parkano Research Unit, FI-39700 Parkano, Finland; Department of Biology, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland.
Department of Biology, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland.
Plant Physiol Biochem. 2015 Mar;88:70-81. doi: 10.1016/j.plaphy.2015.01.009. Epub 2015 Jan 28.
Scots pine (Pinus sylvestris L.) is adapted to various soil types with diverse water availabilities. However, Scots pine seedlings are vulnerable to abiotic stress during the early growth, when they may be exposed to both dry and wet conditions. Here, we focused on the above and below ground coping strategies of Scots pine seedlings under controlled wet, optimal and dry soil conditions by investigating morphological traits including seedling biomass, number of root tips, proportion of mycorrhizal root tips and brown needles. In addition, we studied metabolic and physiological responses including gene expression involved in biosynthesis and catabolism of polyamines (PA), PSII efficiency and the expression of the catalase (CAT) late-embryogenesis abundant protein (LEA), pyruvate decarboxylase (PDC), glutamate-cysteine ligase (GCL) and glutathione synthetase (GS) genes. We found that seedlings invested in shoots by maintaining stable shoot water content and high PSII efficiency under drought stress. Free and soluble conjugated putrescine (Put) accumulated in needles under drought stress, suggesting the role of Put in protection of photosynthesizing tissues. However, the expression of the PA biosynthesis genes, arginine decarboxylase (ADC), spermidine synthase (SPDS) and thermospermine synthase (ACL5) was not affected under drought stress whereas catabolizing genes diamino oxidase (DAO) and polyamine oxidase (PAO) were down-regulated in shoots. The morphology of the roots was affected by peat water content. Furthermore, both drought stress and water excess restricted the seedling ability to sustain a symbiotic relationship. The consistent pattern of endogenous PAs seems to be advantageous to the Scots pine seedlings also under stress conditions.
欧洲赤松（Pinus sylvestris L.）适应具有不同水分可用性的各种土壤类型。然而，欧洲赤松幼苗在早期生长过程中易受到非生物胁迫，此时它们可能会暴露在干燥和潮湿的条件下。在这里，我们通过研究形态特征，包括幼苗生物量、根尖端数量、菌根根尖端的比例和棕色针叶，来研究控制湿地、最佳和干燥土壤条件下欧洲赤松幼苗的地上和地下应对策略。此外，我们还研究了代谢和生理反应，包括参与多胺（PA）生物合成和分解代谢的基因表达、PSII 效率以及过氧化氢酶（CAT）晚期胚胎丰富蛋白（LEA）、丙酮酸脱羧酶（PDC）、谷氨酸-半胱氨酸连接酶（GCL）和谷胱甘肽合酶（GS）基因的表达。我们发现，幼苗通过在干旱胁迫下保持稳定的 Shoot 含水量和高 PSII 效率来投资于 Shoot。游离态和可溶态结合的腐胺（Put）在干旱胁迫下积累在针叶中，表明 Put 在保护光合作用组织中的作用。然而，PA 生物合成基因精氨酸脱羧酶（ADC）、亚精胺合酶（SPDS）和热稳定精胺合酶（ACL5）的表达在干旱胁迫下不受影响，而分解代谢基因二胺氧化酶（DAO）和多胺氧化酶（PAO）在 Shoot 中下调。根的形态受泥炭含水量的影响。此外，干旱胁迫和水分过多都限制了幼苗维持共生关系的能力。内源性 PA 的一致模式似乎对欧洲赤松幼苗在胁迫条件下也有利。
