摘要
【目的】南美油藤种子油中富含不饱和脂肪酸,是一种具有重要经济价值和应用前景的油料植物。目前影响南美油藤种子油脂合成的关键基因、途径及其调控机理尚未清晰。因此,对南美油藤种子的脂质代谢物的动态变化规律及重要脂肪酸代谢相关调控基因的研究,不仅能够为提高其种子油产量和改善油脂品质提供理论基础,也可为其他木本油料植物高效开发利用提供有价值的参考依据。【方法】选用不同生长阶段的南美油藤种子(形成初期、发育初期、中期、后期、成熟期)为研究对象,结合GC-MC代谢组学技术和高通量转录组测序技术,分析种子发育过程中脂质代谢物含量的动态变化规律,并根据种子不同生长阶段的差异表达基因寻找出脂质代谢物生物合成与累积的关联酶基因。【结果】脂质代谢组学分析发现,南美油藤种子中高含量的α-亚麻酸和亚油酸主要在种子成熟阶段合成与累积,是判别南美油藤种子中脂肪酸缓慢累积时期与快速累积阶段的依据。转录组学分析表明,南美油藤种子成熟阶段前后的基因表达存在显著差异。结合代谢组学与转录组学的分析结果显示,与脂肪酸生物合成和累积相关的6个关键酶基因的表达模式与脂肪酸的合成和累积存在显著的相关性,基因家族的不同成员存在生物学功能的差异性和多样性。其中FAD2-3、FAD7、FATA、KAS2、LACS2、LACS8和SAD酶基因表达与脂肪酸总含量及主要脂肪酸含量呈显著正相关,说明7个酶基因表达对南美油藤种子油脂的合成与累积有促进作用;FAD2-2、KCS1、KCS10和LACS1酶基因与脂肪酸总含量及主要脂肪酸含量呈显著负相关,说明4个酶基因的表达对南美油藤种子油脂的合成与累积具有抑制作用。【结论】南美油藤种子成熟前后脂肪酸含量及差异表达基因存在显著差异,可依据种子中α-亚麻酸和亚油酸的含量变化将种子发育过程划分为脂肪酸缓慢累积和快速累积2个时期;南美油藤种子脂肪酸代谢中的6个关键酶基因的表达模式与脂肪酸的合成和累积存在显著的相关性,且同一基因家族的不同成员在脂肪酸的累积过程中可能具有不同的生物学功能。研究结果可为利用分子生物学技术提高南美油藤种子油产量和改变脂肪酸组分提供备选基因和相应的理论基础。
【Objective】 Plukenetia volubilis is an oleaginous plant that contains high content of unsaturated fatty acid in the seed oil.It is a potential economically efficient crop with great possibilities for industrialization.There is a significant research gap in regulatory mechanisms of oil synthesis,related key genes and biosynthetic pathways.Therefore,the study of the dynamic changes rule of lipid metabolites and related regulatory genes of fatty acid metabolism of P.volubilis seeds could lay the foundation for further study on raising seed oil yield and improving seed oil quality and provide a valuable example for efficient development and utilization of other woody oil plants.【Method】 To investigate the dynamic changes of lipid metabolites content,and search for key genes related to biosynthesis and accumulation of lipid metabolites from differentially expressed genes,gas chromatography mass spectrometry based metabolomics approach and high-throughput sequencing technology platform were used to analyze the P.volubilis seeds collected at different growth stages: initial formation stage,early development stage,middle stage,later stage and maturation stage.【Result】 The result of metabolism analysis showed that the high contents of α-linolenic acid and linoleic acid were mainly biosynthesized and accumulated at the seed maturation stage,and the contents of α-linolenic acid and linoleic acid could be the basis for identifying the slow and the rapid accumulation periods.Transcriptome analysis indicated that there were significant differences in gene expression between before and after the stage of seed maturation.The result of combined metabolomics and transcriptomics analysis turned out that the expression patterns of six key enzyme genes related to fatty acid biosynthesis and accumulation were significantly correlated with the biosynthesis and accumulation of fatty acids.And different members of a gene family showed differences and diversity of biological functions.Among them, FAD2-3,FAD7,FATA,KAS2,LACS2,LACS8 and SAD were positively correlated with the contents of total and main fatty acids,indicating that the expression of the seven genes could promote the biosynthesis and accumulation of fatty acids.Moreover,the genes of FAD2-2,KCS1,KCS10 and LACS1 were negatively correlated with the contents of total and main fatty acids,indicating that the expression of the three genes have an inhibitory effect on the biosynthesis and accumulation of fatty acids.【Conclusion】 In the study,there were significant differences in the content of fatty acids and the expression of differentially expressed genes between before and after the stage of P.volubilis seed maturation.Based on the content changes of α-linolenic acid and linoleic acid,the seed development process could be divided into the periods of slow and rapid accumulation of fatty acids. We also explored the dynamic changes of the 6 key enzyme genes and correlation analysis in fatty acids biosynthesis.It was found that the expression patterns of key enzyme genes were significantly correlated to the synthesis and accumulation of fatty acids.Different members of the same gene family might have different biological functions.The results laid a theoretical foundation and provided alternative genes on improving the yield of P.volubilis seed oil and changing the composition of fatty acid by technologies of molecular biology.
作者
刘果
陈鸿鹏
吴志华
彭彦
谢耀坚
Liu Guo;Chen Hongpeng;Wu Zhihua;Peng Yan;Xie Yaojian(China Eucalypt Research Centre Zhanjiang 524022)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2019年第5期169-179,共11页
Scientia Silvae Sinicae
基金
中央级公益性科研院所基本科研业务费专项资金(CAFYBB2016QA018)
广东省林业科技创新项目(2014KJCX016-03)
关键词
南美油藤
代谢组学
转录组学
油脂合成
不饱和脂肪酸
Plukenetia volubilis
metabolomics
transcriptomics
biosynthesis of lipids
unsaturated fatty acid
