Zhang Cheng, Yang Jiabao, Meng Wanqiu, Zeng Linglu, Sun Li
College of Life Sciences, Shihezi University, Shihezi, China.
Front Plant Sci. 2022 Sep 23;13:975853. doi: 10.3389/fpls.2022.975853. eCollection 2022.
The wax esters are important cuticular wax composition that cover the outer surface of plant organs and play a critical role in protection and energy metabolism. Wax ester synthesis in plant is catalyzed by a bifunctional wax ester synthase/acyl-CoA: diacylglycerol acyltransferase (WSD). Sunflower ( L.) is an important oil crop in the world; however, little is known about WSD in sunflower. In this study, we identified and performed a functional analysis of twelve genes from sunflower genome. Tissue-specific expression revealed that 12 genes were differentially expressed in various organs and tissues of sunflower, except seeds. genes were highly induced by salinity, drought, cold, and abscisic acid (ABA) in sunflower. To ascertain their function, , with highly expressed levels in stems and leaves, was cloned and expressed in a yeast mutant defective in triacylglycerol (TAG) biosynthesis. complemented the phenotype by producing wax ester but not TAG , indicating that it functions as a wax ester synthase. Subcellular localization analysis indicated that HaWSD9 was located in the endoplasmic reticulum (ER). Heterologous introduction of into Arabidopsis mutant exhibited increased epicuticular wax crystals and cuticular wax contents on the stems. As compared with the mutant, overexpressing transgenic Arabidopsis showed less cuticle permeability, chlorophyll leaching and water loss rate. Further analysis showed that the transgenics enhanced tolerance to ABA, mannitol, drought and salinity, and maintained higher leaf relative water content (RWC) than the mutant under drought stress, suggesting that play an important physiological role in stress response as well as wax synthase. These results contribute to understanding the function of genes in wax ester synthesis and stress tolerance in sunflower.
蜡酯是覆盖植物器官外表面的重要角质层蜡质成分，在保护和能量代谢中起关键作用。植物中的蜡酯合成由双功能蜡酯合酶/酰基辅酶A：二酰甘油酰基转移酶（WSD）催化。向日葵是世界上重要的油料作物；然而，对向日葵中的WSD了解甚少。在本研究中，我们从向日葵基因组中鉴定并对12个基因进行了功能分析。组织特异性表达显示，除种子外，12个基因在向日葵的各种器官和组织中差异表达。这些基因在向日葵中受到盐度、干旱、寒冷和脱落酸（ABA）的高度诱导。为了确定它们的功能，在茎和叶中高表达的HaWSD9被克隆并在三酰甘油（TAG）生物合成缺陷的酵母突变体中表达。HaWSD9通过产生蜡酯而不是TAG来补充表型，表明它作为蜡酯合酶发挥作用。亚细胞定位分析表明，HaWSD9位于内质网（ER）中。将HaWSD9异源导入拟南芥突变体后，茎上的表皮蜡晶体和角质层蜡含量增加。与突变体相比，过表达HaWSD9的转基因拟南芥显示出更低的角质层通透性、叶绿素渗漏和失水率。进一步分析表明，HaWSD9转基因增强了对ABA、甘露醇、干旱和盐度的耐受性，并且在干旱胁迫下比突变体保持更高的叶片相对含水量（RWC），这表明HaWSD9在应激反应以及蜡合酶方面发挥重要的生理作用。这些结果有助于了解HaWSD基因在向日葵蜡酯合成和胁迫耐受性中的功能。
