Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, S. Michele all'Adige, Trento, Italy.
Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
J Exp Bot. 2017 Apr 1;68(9):2439-2451. doi: 10.1093/jxb/erx125.
Arundo donax has been identified as an important biomass and biofuel crop. Yet, there has been little research on photosynthetic and metabolic traits, which sustain the high productivity of A. donax under drought conditions. This study determined phenotypic differences between two A. donax ecotypes coming from stands with contrasting adaptation to dry climate. We hypothesized that the Bulgarian (BG) ecotype, adapted to drier conditions, exhibits greater drought tolerance than the Italian (IT) ecotype, adapted to a more mesic environment. Under well-watered conditions the BG ecotype was characterized by higher photosynthesis, mesophyll conductance, intrinsic water use efficiency, PSII efficiency, isoprene emission rate and carotenoids, whereas the IT ecotype showed higher levels of hydroxycinnamates. Photosynthesis of water-stressed plants was mainly limited by diffusional resistance to CO2 in BG, and by biochemistry in IT. Recovery of photosynthesis was more rapid and complete in BG than in IT, which may indicate better stability of the photosynthetic apparatus associated to enhanced induction of volatile and non-volatile isoprenoids and phenylpropanoid biosynthesis. This study shows that a large phenotypic plasticity among A. donax ecotypes exists, and may be exploited to compensate for the low genetic variability of this species when selecting plant productivity in constrained environments.
芦竹已被确定为一种重要的生物质和生物燃料作物。然而,对于维持芦竹在干旱条件下高生产力的光合和代谢特性的研究却很少。本研究旨在确定来自对干旱气候具有不同适应能力的两个芦竹生态型之间的表型差异。我们假设,适应较干燥条件的保加利亚(BG)生态型比适应较湿润环境的意大利(IT)生态型具有更强的耐旱性。在水分充足的条件下,BG 生态型的光合作用、叶肉导度、内在水分利用效率、PSII 效率、异戊二烯排放率和类胡萝卜素较高,而 IT 生态型的羟基肉桂酸水平较高。受水分胁迫的植物光合作用主要受到 BG 中 CO2 扩散阻力的限制,而在 IT 中受到生物化学的限制。BG 中的光合作用恢复比 IT 更快、更完全,这可能表明与增强挥发性和非挥发性异戊二烯以及苯丙烷生物合成的诱导相关的光合机构稳定性更好。本研究表明,芦竹生态型之间存在着较大的表型可塑性,在选择受限制环境下植物生产力时,可以利用这种可塑性来弥补该物种遗传变异率低的问题。