The Breakdown of Stored Triacylglycerols Is Required during Light-Induced Stomatal Opening.
The Breakdown of Stored Triacylglycerols Is Required during Light-Induced Stomatal Opening.
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DOI：
10.1016/j.cub.2016.01.019
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发表时间：
2016-03-07
期刊：
影响因子：
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通讯作者：
Hetherington AM
中科院分区：
文献类型：
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作者：
McLachlan DH;Lan J;Geilfus CM;Dodd AN;Larson T;Baker A;Hõrak H;Kollist H;He Z;Graham I;Mickelbart MV;Hetherington AM
气孔调节CO2的吸收和水蒸气的损失，并有助于控制植物的水分利用效率。尽管将蓝光感知与离子通道活性耦合的保卫细胞信号传导途径相对较好地理解，但我们对驱动K+摄取所需的ATP来源知之甚少。在这里，我们表明，三酰基甘油（TAG），目前在拟南芥保卫细胞的脂滴（LD），参与光诱导的气孔开放。光照诱导LD丰度的减少，这涉及PHOT 1和PHOT 2蓝光受体。光还诱导特定TAG分子种类的减少。我们假设TAG衍生的脂肪酸通过过氧化物酶体β-氧化代谢产生气孔开放所需的ATP。计算机模拟分析表明，保卫细胞表达β-氧化所需的所有基因，我们发现，光诱导的气孔开放延迟三个TAG catalysts突变体（sdp 1，pxa 1，和cgi-58）和气孔处理的TAG分解抑制剂。我们推断，如果ATP供应延迟光诱导的气孔开放，那么质膜H+-ATPase的活性应在此时降低。监测突变体中质外体pH的变化表明情况确实如此。总之，我们的研究结果揭示了TAG在营养组织中的新作用，并表明PHOT 1和PHOT 2参与了LD丰度的减少。石松属植物卷柏保卫细胞中LD丰度的减少表明TAG的分解可能代表了光诱导气孔开放的进化保守机制。保卫细胞分解三酰甘油以提供用于气孔开放的ATP光诱导的气孔开放在三酰甘油催化剂突变体中被延迟PHOT蓝光受体参与脂滴（LD）丰度的减少光诱导的LD丰度的减少发生在卷柏属保卫细胞气孔是叶片表面上调节气体交换的孔。McLachlan等人表明储存在保卫细胞脂滴中的三酰甘油被分解，以提供光诱导气孔开放期间所需的ATP。石松卷柏的实验表明，从进化的角度来看，这是一种保守的机制。
Stomata regulate the uptake of CO2 and the loss of water vapor and contribute to the control of water-use efficiency in plants. Although the guard-cell-signaling pathway coupling blue light perception to ion channel activity is relatively well understood, we know less about the sources of ATP required to drive K+ uptake. Here, we show that triacylglycerols (TAGs), present in Arabidopsis guard cells as lipid droplets (LDs), are involved in light-induced stomatal opening. Illumination induces reductions in LD abundance, and this involves the PHOT1 and PHOT2 blue light receptors. Light also induces decreases in specific TAG molecular species. We hypothesized that TAG-derived fatty acids are metabolized by peroxisomal β-oxidation to produce ATP required for stomatal opening. In silico analysis revealed that guard cells express all the genes required for β-oxidation, and we showed that light-induced stomatal opening is delayed in three TAG catabolism mutants (sdp1, pxa1, and cgi-58) and in stomata treated with a TAG breakdown inhibitor. We reasoned that, if ATP supply was delaying light-induced stomatal opening, then the activity of the plasma membrane H+-ATPase should be reduced at this time. Monitoring changes in apoplastic pH in the mutants showed that this was the case. Together, our results reveal a new role for TAGs in vegetative tissue and show that PHOT1 and PHOT2 are involved in reductions in LD abundance. Reductions in LD abundance in guard cells of the lycophyte Selaginella suggest that TAG breakdown may represent an evolutionarily conserved mechanism in light-induced stomatal opening. Guard cells break down triacylglycerols to supply ATP for use in stomatal opening Light-induced stomatal opening is delayed in triacylglycerol catabolism mutants PHOT blue light receptors are involved in reductions in lipid droplet (LD) abundance Light-induced reductions in LD abundance occur in Selaginella guard cells Stomata are pores on the surfaces of leaves that regulate gas exchange. McLachlan et al. show that triacylglycerols stored in guard cell lipid droplets are broken down to provide ATP required during light-induced stomatal opening. Experiments with the lycophyte Selaginella suggest that, in evolutionary terms, this is a conserved mechanism.