The Molecular Cloning and Functional Analysis of the FAD2 Gene in Hippophe rhamnoids L

Seabuckthorn (Hippophae rhamnoides Linn.) is a commonly utilized medicinal crop with various applications in the treatment of different diseases. Two particularly noteworthy nutrients in seabuckthorn fruit are seabuckthorn oil and flavonoids. In recent years, seabuckthorn oil has attracted considerable attention due to its perceived benefits for beauty and healthcare. Consequently, there is a clear need for further research into seabuckthorn oil. While numerous studies have been conducted on the regulation of oil by the FAD2 gene family, there is a paucity of literature examining the molecular mechanism of FAD2 gene involvement in seabuckthorn oil regulation. Accordingly, two FAD2 genes have been identified in seabuckthorn, which are classified differently and perform distinct functions. Both genes are located in the endoplasmic reticulum. Following transient expression in seabuckthorn fruits, it was observed that HrFAD2-1 and HrFAD2-3 were capable of influencing the synthesis of α-linolenic acid, with HrFAD2-1 additionally demonstrated to facilitate the synthesis of lysophosphatidic acid. All of the aforementioned genes have been observed to promote jasmonic acid (JA) synthesis. The heterologous transformation of Linum usitatissimum demonstrates that both HrFAD2-1 and HrFAD2-3 are capable of promoting plant growth. The HrFAD2-1 gene was observed to significantly increase the content of major fatty acids in Linum usitatissimum Linn seeds, whereas the HrFAD2-3 gene appeared to be primarily involved in the regulation of plant growth and development. In conclusion, a preliminary investigation into the functions of the HrFAD2-1 and HrFAD2-3 genes in fatty acid synthesis was conducted. This revealed that HrFAD2-1 is closely associated with oleic acid synthesis and acts as a negative regulator. Furthermore, our findings will provide a foundation for subsequent investigations into the fatty acid synthesis pathway in Hippophae rhamnoides oil, offering a theoretical basis for subsequent studies at the molecular level.