Key message

A 3-ketoacyl-CoA synthase involved in biosynthesis of very long chain fatty acids and cuticular wax plays a vital role in aerial organ development in M. truncatula.

Abstract

Cuticular wax is composed of very long chain fatty acids and their derivatives. Defects in cuticular wax often result in organ fusion, but little is known about the role of cuticular wax in compound leaf and flower development in Medicago truncatula. In this study, through an extensive screen of a Tnt1 retrotransposon insertion population in M. truncatula, we identified four mutant lines, named wrinkled flower and leaf (wfl) for their phenotype. The phenotype of the wfl mutants is caused by a Tnt1 insertion in Medtr3g105550, encoding 3-ketoacyl-CoA synthase (KCS), which functions as a rate-limiting enzyme in very long chain fatty acid elongation. Reverse transcription-quantitative PCR showed that WFL was broadly expressed in aerial organs of the wild type, such as leaves, floral organs, and the shoot apical meristem, but was expressed at lower levels in roots. In situ hybridization showed a similar expression pattern, mainly detecting the WFL transcript in epidermal cells of the shoot apical meristem, leaf primordia, and floral organs. The wfl mutant leaves showed sparser epicuticular wax crystals on the surface and increased water permeability compared with wild type. Further analysis showed that in wfl leaves, the percentage of C20:0, C22:0, and C24:0 fatty acids was significantly increased, the amount of cuticular wax was markedly reduced, and wax constituents were altered compared to the wild type. The reduced formation of cuticular wax and wax composition changes on the leaf surface might lead to the developmental defects observed in the wfl mutants. These findings suggest that WFL plays a key role in cuticular wax formation and in the late stage of leaf and flower development in M. truncatula.

中文翻译：

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3-酮脂酰辅酶 A 合酶 WFL 参与蒺藜苜蓿的侧向器官发育和表皮蜡合成

关键信息

一种参与超长链脂肪酸和表皮蜡生物合成的 3-酮脂酰辅酶 A 合酶在蒺藜苜蓿的气生器官发育中起着至关重要的作用。

抽象的

角质层蜡由非常长的链脂肪酸及其衍生物组成。角质层蜡质缺陷常导致器官融合，但角质层蜡质在蒺藜苜蓿复叶和花发育中的作用知之甚少。在这项研究中，通过对蒺藜苜蓿中 Tnt1 反转录转座子插入种群的广泛筛选，我们确定了四个突变株系，它们的表型被命名为皱纹花和叶( wfl )。wfl突变体的表型是由 Medtr3g105550 中的Tnt1插入引起的, 编码 3-酮脂酰辅酶 A 合酶 (KCS)，它在超长链脂肪酸延伸中起限速酶的作用。逆转录-定量PCR显示WFL在野生型的气生器官中广泛表达，如叶片、花器官和茎尖分生组织，但在根中表达水平较低。原位杂交显示出相似的表达模式，主要检测茎尖分生组织、叶原基和花器官的表皮细胞中的WFL转录物。与野生型相比，wfl突变体叶片表面的表皮蜡晶体稀疏，透水性增加。进一步分析表明，在wfl与野生型相比，C20:0、C22:0、C24:0脂肪酸含量显着增加，表皮蜡质含量明显减少，蜡质成分发生变化。表皮蜡的形成减少和叶表面蜡成分的变化可能导致在wfl突变体中观察到的发育缺陷。这些发现表明，WFL在蒺藜苜蓿的表皮蜡形成和叶片和花发育的后期发挥着关键作用。