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Differential Activation of Partially Redundant Δ9 Stearoyl-ACP Desaturase Genes is Critical for Omega-9 Monounsaturated Fatty Acid Biosynthesis During Seed Development in Arabidopsis.
The Plant Cell ( IF 11.6 ) Pub Date : 2020-11-01 , DOI: 10.1105/tpc.20.00554
Sami Kazaz 1 , Guillaume Barthole 1 , Frédéric Domergue 2, 3 , Hasna Ettaki 1 , Alexandra To 1 , Damien Vasselon 1 , Delphine De Vos 1 , Katia Belcram 1 , Loïc Lepiniec 1 , Sébastien Baud 4
Affiliation  

The spatiotemporal pattern of deposition, final amount, and relative abundance of oleic acid (cis--9 C18:1) and its derivatives in the different lipid fractions of the seed of Arabidopsis (Arabidopsis thaliana) indicates that omega-9 monoenes are synthesized at high rates in this organ. Accordingly, we observed that four 9 stearoyl-ACP desaturase (SAD)-coding genes (FATTY ACID BIOSYNTHESIS2 [FAB2], ACYL-ACYL CARRIER PROTEIN5 [AAD5], AAD1, and AAD6) are transcriptionally induced in seeds. We established that the three most highly expressed ones are directly activated by the WRINKLED1 transcription factor. We characterized a collection of 30 simple, double, triple, and quadruple mutants affected in SAD-coding genes and thereby revealed the functions of these desaturases throughout seed development. Production of oleic acid by FAB2 and AAD5 appears to be critical at the onset of embryo morphogenesis. Double homozygous plants from crossing fab2 and aad5 could never be obtained, and further investigations revealed that the double mutation results in the arrest of embryo development before the globular stage. During later stages of seed development, these two SADs, together with AAD1, participate in the elaboration of the embryonic cuticle, a barrier essential for embryo–endosperm separation during the phase of invasive embryo growth through the endosperm. This study also demonstrates that the four desaturases redundantly contribute to storage lipid production during the maturation phase.



中文翻译:

部分冗余的 Δ9 硬脂酰-ACP 去饱和酶基因的差异激活对于拟南芥种子发育过程中的 Omega-9 单不饱和脂肪酸生物合成至关重要。

拟南芥 ( Arabidopsis thaliana ) 种子不同脂质部分中油酸 ( cis --9 C18:1) 及其衍生物的沉积时空模式、最终量和相对丰度表明 omega-9 单烯的合成时间为这个器官的比率很高。因此,我们观察到四个 9 硬脂酰 ACP 去饱和酶 (SAD) 编码基因(脂肪酸生物合成 2 [ FAB2 ]、酰基-酰基载体蛋白 5 [ AAD5 ]、AAD1AAD6)在种子中被转录诱导。我们确定三个表达最高的基因是由 WRINKLED1 转录因子直接激活的。我们对 30 个受 SAD 编码基因影响的简单、双、三和四突变体进行了表征,从而揭示了这些去饱和酶在整个种子发育过程中的功能。FAB2 和 AAD5 产生油酸似乎对于胚胎形态发生的开始至关重要。fab2aad5杂交的双纯合植物永远无法获得,进一步的研究表明,双重突变导致胚胎发育在球状阶段之前停滞。在种子发育的后期阶段,这两个 SAD 与 AAD1 一起参与胚胎角质层的形成,胚胎角质层是通过胚乳侵入性胚胎生长阶段胚胎与胚乳分离所必需的屏障。这项研究还表明,四种去饱和酶对成熟阶段储存脂质的产生有多余的贡献。

更新日期:2020-11-03
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