SAD和FAD家族基因调控山核桃不饱和脂肪酸组分配比

以山核桃胚为试材,测定5个山核桃油脂合成积累关键时期(授粉后75、85、100、109和127 d)的油脂组分和油含量,并利用实时荧光定量PCR检测山核桃Δ9–硬脂酰–ACP脱氢酶(SAD)基因(CcSAD-1、CcSAD-2、CcSAD-3)和山核桃脂肪酸去饱和酶(FAD)基因(CcFAD2、CcFAD3-1、CcFAD3-2、CcFAD3-3、CcFAD6、CcFAD7、CcFAD8-1、CcFAD8-2、CcFAD8-3)的表达模式。结果表明:成熟的山核桃种仁含油率超过种仁干质量的70%,同时不饱和脂肪酸比例达到90%以上;山核桃5个时期的脂肪酸组分,主要由棕榈酸(C16︰0)、硬脂酸(C18︰0)、油酸(C18︰1)、亚油酸(C18︰2)以及亚麻酸(C18︰3)组成;随着山核桃SAD家族基因表达上升,山核桃油中的油酸含量上升并维持一定水平,其中CcSAD-3可能是影响油酸含量的主效基因;同时随着山核桃油酸含量上升,CcFADs基因表达上升,山核桃不饱和脂肪酸比例增加。

SAD and FAD Genes Regulate the Ratio of Unsaturated Fatty Acid Components in Carya cathayensis

Taking the hickory（Carya cathayensis Sarg.）embryo as the test material，five periods（75，85，100，109 and 127 days after pollination）of hickory embryo which are critical for the oil synthesis and integration are measured by gas chromatography to study the law of hickory oil. Additionally，Stearoyl- ACP desaturase genes（CcSAD-1，CcSAD-2，CcSAD-3）and fatty acid desaturase genes（CcFAD2，CcFAD3-1，CcFAD3-2，CcFAD3-3，CcFAD6，CcFAD7，CcFAD8-1，CcFAD8-2，CcFAD8-3）were studied by quantitative real-time PCR. The results revealed that hickory oil mainly composed of palmitic acid（C16︰0），stearic acid（C18︰0），oleic acid（C18︰1），linoleic acid（C18︰2）and linolenic acid（C18︰3）；hickory is a high oleic species. In addition，quantitative results showed that with the increase of Stearoyl- ACP desaturase genes expression，the oleic acid content in hickory oil increased and reached dynamic balance. Gene expression profiling and lipid analysis in hickory fruit during development identify CcSAD-3 as the main gene responsible for the oleic acid content in hickory oil. Meanwhile，with the increase of oleic acid content in the hickory oil，the expression of CcFADs increased，and the proportion of unsaturated fatty acids in hickory oil increased.