Guard cell photosynthesis is critical for stomatal turgor production, yet does not directly mediate CO2 - and ABA-induced stomatal closing.
Guard cell photosynthesis is critical for stomatal turgor production, yet does not directly mediate CO2 - and ABA-induced stomatal closing.
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DOI：
10.1111/tpj.12916
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发表时间：
2015-08
期刊：
影响因子：
--
通讯作者：
Schroeder JI
中科院分区：
文献类型：
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作者：
Azoulay-Shemer T;Palomares A;Bagheri A;Israelsson-Nordstrom M;Engineer CB;Bargmann BO;Stephan AB;Schroeder JI
气孔介导叶片细胞间隙与大气之间的气体交换。叶片中的CO2水平（Ci）由呼吸作用、光合作用、气孔导度和大气[CO2]决定。[CO2]介导气孔运动。保卫细胞光合作用在气孔导度反应中的作用是一个有争议的问题，需要遗传方法。我们已经产生了转基因拟南芥植物是叶绿素缺乏的保卫细胞，表达组成型活性叶绿素酶的保卫细胞特异性增强子陷阱线。我们的数据表明，超过90%的保卫细胞叶绿素缺乏。有趣的是，约45%的气孔有一个不寻常的，以前没有描述过，形态薄形叶绿素少气孔。然而，气孔大小，气孔指数，植株形态，和全叶光合参数（PSII，qP，qN，FV′/FM′）与野生型植株相当。时间分辨完整叶片气体交换分析表明，气孔导度和碳同化率的转基因植物的减少。CO2响应的归一化表明，转基因植物的气孔响应[CO2]的变化。详细的气孔孔径测量正常肾形气孔，缺乏叶绿素，气孔关闭响应[CO2]海拔和脱落酸（阿坝），而薄形气孔持续关闭。我们目前的研究结果表明，气孔运动响应[CO2]和阿坝的功能在保卫细胞缺乏叶绿素。这些数据表明，保卫细胞CO2和阿坝信号转导不直接调制保卫细胞光合作用/电子传递。此外，发现叶绿素少气孔导致“瘪”薄形表型，表明光合作用在保卫细胞是至关重要的光合作用和保卫细胞膨压生产。
Stomata mediate gas exchange between the inter-cellular spaces of leaves and the atmosphere. CO2 levels in leaves (Ci) are determined by respiration, photosynthesis, stomatal conductance and atmospheric [CO2]. [CO2] in leaves mediates stomatal movements. The role of guard-cell photosynthesis in stomatal conductance responses is a matter of debate, and genetic approaches are needed. We have generated transgenic Arabidopsis plants that are chlorophyll-deficient in guard cells only, expressing a constitutively active chlorophyllase in a guard-cell specific enhancer trap-line. Our data show that more than 90% of guard cells were chlorophyll-deficient. Interestingly, approximately ~ 45% of stomata had an unusual, previously not-described, morphology of thin-shaped chlorophyll-less stomata. Nevertheless, stomatal size, stomatal index, plant morphology, and whole-leaf photosynthetic parameters (PSII, qP, qN, FV′/FM′) were comparable to wild-type plants. Time-resolved intact leaf gas exchange analyses showed a reduction in stomatal conductance and carbon assimilation rates of the transgenic plants. Normalization of CO2 responses showed that stomata of transgenic plants respond to [CO2] shifts. Detailed stomatal aperture measurements of normal kidney-shaped stomata, which lack chlorophyll, showed stomatal closing responses to [CO2] elevation and abscisic acid (ABA), while thin-shaped stomata were continuously closed. Our present findings show that stomatal movement responses to [CO2] and ABA are functional in guard cells that lack chlorophyll. These data suggest that guard-cell CO2 and ABA signal transduction are not directly modulated by guard-cell photosynthesis/electron transport. Moreover, the finding that chlorophyll-less stomata cause a “deflated” thin-shaped phenotype, suggests that photosynthesis in guard cells is critical for energization and guard-cell turgor production.