翅果油树脂肪酸生物合成调控机制研究

[Objective]In recent years,Elaeagnus mollis,as an emerging and unique woody oil tree species in northern China,has received more and more attention.Its kernels contain high levels of unsaturated fatty acids such as oleic acid and linoleic acid.At present,the key genes,transcription factors and their regulatory mechanisms affecting the biosynthesis of kernel fatty acids in Elaeagnus mollis are still unclear.Therefore,this study studied the dynamic changes in fatty acid content and regulatory genes of the Elaeagnus mollis kernels at different developmental stages,which not only contributes to a comprehensive understanding of the regulatory mechanisms of fatty acid biosynthesis in Elaeagnus mollis,but also lays a solid foundation for further genetic breeding.[Method]In the present study,gas chromatography-mass spectrometry(GC-MS)and transcriptomic analysis were conducted to quantify fatty acid content dynamic and the molecular regulatory mechanism of Elaeagnus mollis kernel at different developmental stages,and the key enzyme genes and transcription factors related to the fatty acid biosynthesis of Elaeagnus mollis were screened out.[Result]At the end of development,unsaturated fatty acids accounted for more than 90%of the total fatty acids,with oleic acid and linoleic acid reaching up to 56.03mg/g oil(42.35%)and 56.69mg/g oil(42.85%).Transcriptomic analysis revealed 436 genes related to lipid metabolism pathways,including 179 genes directly involved in fatty acid synthesis,and 2735 genes associated with carbohydrate metabolism pathways.Combined with the dynamic changes of fatty acid content and transcriptomic analysis,the expression of 5 EmSAD genes and 3 EmFAD2 genes played an important role in the synthesis and accumulation of kernel oleic acid and linoleic acid in Elaeagnus mollis seeds,and the middle stage of development may be the key stage of the synthesis and accumulation of oleic acid and linoleic acid in Elaeagnus mollis.Weighted gene co-expression network analysis demonstrated a significant positive correlation between the turquoise module and oleic acid and linoleic acid content,and the blue module was negatively correlated with oleic acid and linoleic acid content.Co-expression network analysis indicated that EmWRI1 was a potential important regulator in the fatty acid biosynthesis of Elaeagnus mollis.The promoters of one EmFAD2 gene and two EmPDAT genes that were significantly positively correlated with the expression of EmWRI1(evm.TU.Chr04.576)were cloned,and the AW-BOX elements specifically bound to EmWRI1 were identified,suggesting that WRI1 may bind to these cis-elements and regulate their expression during kernel fatty acid biosynthesis in Elaeagnus mollis.[Conclusion]Fatty acid synthesis in Elaeagnus mollis is a complex process involving a large number of genes,including genes directly involved in fatty acid synthesis and other genes involved in lipid metabolism.The transcription factor EmWRI1 may be a key factor in regulating this process,while the positive correlation of specific gene modules(e.g.,turquoise module)with fatty acid content may indicate their potential role in fatty acid synthesis.