Aquaporins are major determinants of water use efficiency of rice plants in the field
Aquaporins are major determinants of water use efficiency of rice plants in the field
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DOI：
10.1016/j.plantsci.2014.08.006
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发表时间：
2014-10-01
期刊：
影响因子：
5.2
通讯作者：
Abogadallah, Gaber M.
中科院分区：
文献类型：
--
作者：
Nada, Reham M.;Abogadallah, Gaber M.
本研究旨在明确中午田间水分关系不平衡导致粳稻和籼稻在水分充足和干旱条件下光合作用减慢和水分利用效率（WUE）降低的原因。田间中午浇水充足的植物叶片相对含水量（RWC）下降，但干旱的籼稻品种（75.6%和71.4%）比粳稻品种（85.5%和80.8%）下降幅度更大。一天中的三个时间点（9:00、13:00 和 17:00）测量气体交换。当中午气孔抑制最高时，叶片内部 CO2 (C-i) 并未耗尽，这表明 C-i 并不限制光合作用。大多数水通道蛋白主要在叶子中表达，表明叶子的透水性高于根。 9:00 的干旱进一步诱导了叶水通道蛋白的表达，而根部没有类似的反应。数据表明根内皮层中水通道蛋白的表达限制了水的吸收。去除根部水流的径向障碍后，蒸腾作用立即增加，4 小时后光合作用增加，导致 4 小时后 WUE 增加，表明水稻中的 WUE 在很大程度上受到根部水通道蛋白表达谱不足的限制。 (C) 2014 Elsevier Ireland Ltd. 保留所有权利。
This study aimed at specifying the reasons of unbalanced water relations of rice in the field at midday which results in slowing down photosynthesis and reducing water use efficiency (WUE) in japonica and indica rice under well-watered and droughted conditions. Leaf relative water content (RWC) decreased in the well-watered plants at midday in the field, but more dramatically in the droughted indica (75.6 and 71.4%) than japonica cultivars (85.5 and 80.8%). Gas exchange was measured at three points during the day (9:00, 13:00 and 17:00). Leaf internal CO2 (C-i) was not depleted when midday stomatal depression was highest indicating that C-i was not limiting to photosynthesis. Most aquaporins were predominantly expressed in leaves suggesting higher water permeability in leaves than in roots. The expression of leaf aquaporins was further induced by drought at 9:00 without comparable responses in roots. The data suggest that aquaporin expression in the root endodermis was limiting to water uptake. Upon removal of the radial barriers to water flow in roots, transpiration increased instantly and photosynthesis increased after 4 h resulting in increasing WUE after 4 h, demonstrating that WUE in rice is largely limited by the inadequate aquaporin expression profiles in roots. (C) 2014 Elsevier Ireland Ltd. All rights reserved.