| 越南油茶脂肪酸积累及相关基因表达动态分析 |
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| 作者姓名： | 郭钰柬 王红 周开兵 王珮璇 杨成坤 陈静 |
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| 作者单位： | 海南大学热带作物新品种选育教育部工程研究中心 |
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| 基金项目： | 海南省自然科学基金青年项目(318QN199);海南省重大科技计划项目(No.SQ2017GXNY0010)。 |
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| 摘 要： | 越南油茶(Camellia vietnamensis)茶籽油脂肪酸组成差异是影响其营养和医疗保健价值的重要因素,但目前关于其种子油主要脂肪酸含量动态变化及其分子调控机制仍不清楚。本文以16年生越南油茶实生树种子为试验材料,采用索氏提取法提油,采用气相色谱法鉴定脂肪酸种类和测定脂肪酸含量,采用荧光定量PCR法测定4个关键酶基因的相对表达量。结果表明,越南油茶茶籽油中共含有15种脂肪酸,其中棕榈酸、硬脂酸、油酸、亚油酸、亚麻酸、棕榈油酸和二十四碳一烯酸的含量在其动态变化的不同时期间存在显著变化,且油酸和亚油酸、饱和脂肪酸和不饱和脂肪酸等的含量之间分别呈极显著负相关关系;8月5日到9月5日是油酸快速积累期,且油酸的积累随着种子的成熟而增加,亚油酸的积累则与之相反;不同脂肪酸含量与控制其转化的关键酶基因相对表达量动态变化特点基本一致,关键酶基因的相对表达量与硬脂酸(底物)、亚麻酸和花生一烯酸(最终的生成物)等含量之间具有极显著的典型性相关性;△9硬脂酰-ACP脱饱和酶基因(SAD)相对表达量与硬脂酸含量的偏相关系数显著且呈负相关,硬脂酸含量与脂肪酸脱饱和酶2基因(FAD2)相对表达量、SAD与FAD2和脂肪酸脱饱和酶3基因(FAD3)相对表达量、亚油酸含量与FAD3基因相对表达量等之间的偏相关系数均显著且呈正相关。可见,越南油茶茶籽油存在棕榈酸向硬脂酸、硬脂酸向油酸、油酸向亚油酸和亚油酸向亚麻酸的直接转化过程,选择合适的采果日期是提高茶籽油不饱和脂肪酸比例的有效手段之一,SAD基因表达增强促进硬脂酸向油酸转化,硬脂酸含量对FAD2基因表达、亚油酸含量对FAD3基因表达、SAD基因表达对FAD2和FAD3基因表达等均表现正调控作用。
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| 关 键 词： | 越南油茶 脂肪酸 基因表达 动态变化 |
Dynamic changes of fatty acid accumulation and related gene expression in Camellia vietnamensis |
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| Authors: | GUO Yujian WANG Hong ZHOU Kaibing WANG Peixuan YANG Chengkun CHEN Jing |
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| Institution: | (Engineering Research Center of Selecting and Breeding New Tropical Crops Varieties,Hainan University,Minstry of Education,Haikou,Hainan 570228,China) |
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| Abstract: | The fatty acid(FA)composition of Camellia vietnamensis seed oil is an important factor affecting its nutritional and health values,but the dynamic changes and molecular regulation mechanism of the FAs in this seed oil are still unclear.The seeds from 16-year-old seedlings were used as experimental materials,and the Soxhlet method was used to extract oil.We used gas chromatography to determine the kinds and relative content of FAs.The relative expression of four key enzyme genes was determined using real-time polymerase chain reaction.The results showed that there were 15 kinds of FAs in the seed oil and that the proportions of palmitic acid,stearic acid,oleic acid,linoleic acid,linolenic acid,and tetracosenic acid all changed significantly in the course of their dynamic changes.Additionally,there was an extremely significant negative correlation between the contents of oleic acid and linoleic acid,similar to the correlation between those of saturated FAs and unsaturated FAs.Oleic acid accumulated rapidly from August 5th to September 5th,and this accumulation increased with the maturity of the seeds,while the accumulation of linoleic acid showed the opposite trend.Different FA contents changed in accordance with the relative expression of key enzyme genes controlling their transformation.The canonical correlation between the relative expression of key enzyme genes and the stearic acid(substrate),linolenic acid,and arachidonic acid(product)content was extremely significant.The relative expression of the SAD gene was significantly negatively correlated with the stearic acid content.The stearic acid content was significantly positively correlated with the relative expression of the FAD2 gene,as well as that of the SAD with FAD2 and FAD3 genes,similar to the correlation between linoleic acid content and the relative expression of FAD3 gene.It is evident that there was a direct transformation from palmitic acid to stearic acid,from stearic acid to oleic acid,from oleic acid to linoleic acid,and from linoleic acid to linolenic acid.Choosing the right date for harvesting is one effective way to increase the proportion of unsaturated FAs in seed oil.The enhancement of SAD gene expression promoted the transformation from stearic acid to oleic acid.Stearic acid content has a positive effect on the expression of the FAD2 gene,similar to the effect of linoleic acid content on FAD 3 gene expression,as well as that of the SAD gene on FAD 2 and FAD 3 gene expression. |
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| Keywords: | Camellia vietnamensis T C Huang ex Hu fatty acid gene expression dynamic change |
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