Characterization of fatty acid conversion enzymes of soybean and their application for improvement of soybean oil quality

以前，我们已经报道了从x射线照射的大豆后代中建立了许多脂肪酸突变体。在本研究中，我们利用遗传学和分子生物学的方法分析了它们的突变体，并确定了参与脂肪酸合成途径的基因家族。由此得出结论：sop]和sop2基因控制高棕榈酸性状，st1和st2基因控制高硬脂酸性状，ol基因控制高油酸性状，fan和fanx基因分别控制低亚麻酸性状。从大豆种子cDNA文库中分离到编码硬脂酰acp去饱和酶、微粒体欧米茄-6脂肪酸去饱和酶和微粒体欧米茄-3脂肪酸去饱和酶的cDNA克隆。其中3个分别被鉴定为stl、ol和fan基因的对应克隆。此外，我们分析了这些基因在植物激素处理下的表达，发现质体和微粒体欧米茄-6去饱和酶基因的mRNA积累量协同降低，而欧米茄-3去饱和酶基因的mRNA积累量协同增加。

Previously, we have reported to establish many fatty acid-mutants from X-ray irradiated soybean progenies.In this research, we analyzed their mutants using genetical and molecular biological approach, and then identified the gene family that is involved in fatty acid synthesis pathway. These results lead to conclusion that sop] and sop2 genes control the high palmitic acid character, st1 and st2 genes control the high stearic acid character, ol gene controls high oleic acid character, and fan and fanx genes control low linolenic acid character, respectively.We could isolate some cDNA clones encoding stearoyl-ACP desaturase, microsomal omega-6 fatty acid desaturase and microsomal omega-3 fatty acid desaturase from soybean seed cDNA library. Three of them were identified as corresponding clones to stl, ol and fan genes, respectively.Furthermore, we analyzed the expression of these genes under phytohormone treatments, and found that mRNA accumulations of both plastidal and microsomal omega-6 desaturase genes coordinately decreased, in contrast, that of omega-3 desaturase genes coordinately increased.