Forest Botany and Tree Physiology, University of Goettingen, 37077, Göttingen, Germany.
Forest Genetics and Plant Physiology, Umea Plant Science Centre, 90736, Umea, Sweden.
New Phytol. 2019 Aug;223(3):1192-1203. doi: 10.1111/nph.15878. Epub 2019 Jun 3.
Abscisic acid (ABA) is a well known stress hormone regulating drought adaptation of plants. Here, we hypothesised that genetic engineering of genes involved in ABA stress signalling and photoperiodic regulation affected drought resistance by trade-off with biomass production in perennial poplar trees. We grew Populus tremula × tremuloides wild-type (T89) and various transgenic lines (two transformation events of 35S::abi1-1, 35S::RCAR, RCAR:RNAi, 35S::ABI3, 35S::AREB3, 35S::FDL1, FDL1:RNAi, 35S::FDL2 and FDL2:RNAi) outdoors and exposed them to drought in the second growth period. After the winter, the surviving lines showed a huge variation in stomatal conductance, leaf size, whole-plant leaf area, tree height, stem diameter, and biomass. Whole-plant leaf area was a strong predictor for woody biomass production. The 35S::AREB3 lines were compromised in biomass production under well irrigated conditions compared with wild-type poplars but were resilient to drought. ABA signalling regulated FDL1 and FDL2 expression under stress. Poplar lines overexpressing FDL1 or FDL2 were drought-sensitive; they shed leaves and lost root biomass, whereas the FDL RNAi lines showed higher biomass allocation to roots under drought. These results assign a new function in drought acclimation to FDL genes aside from photoperiodic regulation. Our results imply a critical role for ABA-mediated processes in balancing biomass production and climate adaptation.
脱落酸（ABA）是一种众所周知的应激激素，可调节植物的耐旱性。在这里，我们假设通过对参与 ABA 应激信号转导和光周期调节的基因进行遗传工程改造，会影响多年生杨树的耐旱性，因为这会与生物量的产生产生权衡。我们在户外种植了颤杨杂种（T89）和各种转基因株系（两个转化事件为 35S::abi1-1、35S::RCAR、RCAR:RNAi、35S::ABI3、35S::AREB3、35S::FDL1、FDL1:RNAi、35S::FDL2 和 FDL2:RNAi），并在第二个生长季节对它们进行干旱处理。冬季过后，存活的株系在气孔导度、叶面积、整株叶面积、树高、茎直径和生物量方面表现出巨大的差异。整株叶面积是木质生物质产量的一个强有力的预测指标。与野生型杨树相比，35S::AREB3 株系在充分灌溉条件下的生物量生产受到影响，但对干旱有抵抗力。ABA 信号转导在胁迫下调节 FDL1 和 FDL2 的表达。过表达 FDL1 或 FDL2 的杨树株系对干旱敏感；它们落叶且失去根生物量，而 FDL RNAi 株系在干旱条件下对根的生物量分配更高。这些结果除了光周期调节之外，还为 FDL 基因在耐旱性方面赋予了新的功能。我们的研究结果表明，ABA 介导的过程在平衡生物量生产和气候适应方面起着关键作用。
