Rodr Guez-Calcerrada Jes S, Shahin Oula, Del Carmen Del Rey Mar A, Rambal Serge
Centre of Functional and Evolutionary Ecology, CNRS 1919 Route de Mende, 34293, Montpellier Cedex 5, France.
Funct Plant Biol. 2011 Dec;38(12):1004-1015. doi: 10.1071/FP11135.
The decline in net photosynthetic CO2 uptake (An) caused by drought could reduce the availability of soluble sugars and thus limit leaf dark respiration (Rd). We investigated the response of leaf gas exchange and nonstructural carbohydrates to drought by stopping watering to 2-year-old plants of Quercus ilex L. and Quercus pubescens Willd. grown in large pots. An declined with increasing water deficit more rapidly than Rd, and Rd declined slightly more steeply in Q. ilex than in Q. pubescens. Soluble sugars increased in drought-treated plants relative to control well watered plants, and the opposite pattern was found for starch. After rewatering, Rd returned to pre-drought rates within 2 days and An within 1 week. Soluble sugars tended to recover pre-drought values after rewatering but continued to be significantly higher in drought-treated than control plants of Q. pubescens, for which the increase in the concentration of soluble sugars had been higher. These results suggest that the relative production of soluble sugars is upregulated when An is limited, and that soluble sugars do not control respiratory rates in response to and recovery from water deficit. Rather, we suggest that the decline in Rd contributes to drought tolerance by reducing the consumption of soluble sugars, which play an important role as osmoprotectants during water deficit stress.
干旱导致的净光合二氧化碳吸收量（An）下降会降低可溶性糖的可用性，从而限制叶片暗呼吸（Rd）。我们通过停止给种植在大花盆中的2年生冬青栎（Quercus ilex L.）和柔毛栎（Quercus pubescens Willd.）浇水，研究了叶片气体交换和非结构性碳水化合物对干旱的响应。随着水分亏缺加剧，An的下降速度比Rd更快，并且在冬青栎中Rd的下降幅度比柔毛栎略大。与充分浇水的对照植株相比，干旱处理植株中的可溶性糖增加，而淀粉的情况则相反。重新浇水后，Rd在2天内恢复到干旱前的速率，An在1周内恢复。重新浇水后，可溶性糖倾向于恢复到干旱前的值，但在柔毛栎中，干旱处理植株中的可溶性糖浓度仍显著高于对照植株，其可溶性糖浓度增加幅度更大。这些结果表明，当An受到限制时，可溶性糖的相对产量会上调，并且可溶性糖不会控制水分亏缺响应及恢复过程中的呼吸速率。相反，我们认为Rd的下降通过减少可溶性糖的消耗有助于耐旱性，可溶性糖在水分亏缺胁迫期间作为渗透保护剂发挥重要作用。
