The acyltransferase GPAT5 is required for the synthesis of suberin in seed coat and root of Arabidopsis
The acyltransferase GPAT5 is required for the synthesis of suberin in seed coat and root of Arabidopsis
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DOI：
10.1105/tpc.106.048033
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发表时间：
2007-01-01
期刊：
影响因子：
11.6
通讯作者：
Ohlrogge, John B.
中科院分区：
文献类型：
--
作者：
Beisson, Fred;Li, Yonghua;Ohlrogge, John B.
软木素和角质是基于脂肪酸和甘油的植物聚合物，其充当病原体屏障并在控制水和溶质运输中起作用。然而，尽管重要的生理作用，其生物合成途径，包括酰基转移反应，仍然是假设。我们报道了拟南芥GPAT 5的两个木栓素突变体（gpat 5 -1和gpat 5 -2）的特征，其编码具有酰基CoA：甘油-3-磷酸酰基转移酶活性的蛋白。RT-PCR和β-葡萄糖醛酸酶-启动子融合分析表明GPAT 5在种皮、根、下胚轴和花药中表达。gpat 5植物表现出50%的脂肪族木栓质在年轻的根减少，并产生种皮的非常长链的二羧酸和ω-羟基脂肪酸木栓质典型的几倍减少，但没有变化的膜或存储甘油脂或表面蜡的组成或含量。与木栓质的改变相一致，gpat 5突变体的种皮对四唑盐的渗透性比野生型种皮有急剧的增加。而且，高盐处理降低了gpat 5种子的发芽率，gpat 5幼苗对盐胁迫的耐受性较低。这些结果为GPAT 5在种皮和根中聚酯生物合成中的关键作用以及脂质聚合物结构在这些器官的正常功能中的重要性提供了证据。
Suberin and cutin are fatty acid-and glycerol-based plant polymers that act as pathogen barriers and function in the control of water and solute transport. However, despite important physiological roles, their biosynthetic pathways, including the acyl transfer reactions, remain hypothetical. We report the characterization of two suberin mutants (gpat5-1 and gpat5-2) of Arabidopsis thaliana GPAT5, encoding a protein with acyl-CoA:glycerol-3-phosphate acyltransferase activity. RT-PCR and beta-glucuronidase-promoter fusion analyses demonstrated GPAT5 expression in seed coat, root, hypocotyl, and anther. The gpat5 plants showed a 50% decrease in aliphatic suberin in young roots and produced seed coats with a severalfold reduction in very long chain dicarboxylic acid and omega-hydroxy fatty acids typical of suberin but no change in the composition or content of membrane or storage glycerolipids or surface waxes. Consistent with their altered suberin, seed coats of gpat5 mutants had a steep increase in permeability to tetrazolium salts compared with wild-type seed coats. Furthermore, the germination rate of gpat5 seeds under high salt was reduced, and gpat5 seedlings had lower tolerance to salt stress. These results provide evidence for a critical role of GPAT5 in polyester biogenesis in seed coats and roots and for the importance of lipid polymer structures in the normal function of these organs.