Expression patterns of four key genes involved in strawberry eugenol synthesis under abiotic stresses

Eugenol is an important phenylpropanoid in strawberry and the accumulation is affected by various abiotic stresses. In this study, the expression patterns of two transcription factors (TFs) (FaMYB10 and FaEOBII) and two synthetic genes (FaEGS1 and FaEGS2) involved in eugenol synthesis were characterized in Fragaria × ananassa cv. ‘Xiaobai’. Sequence analysis showed the four genes contained several cis-acting elements that were related to phytohormones and environmental stress signal responsiveness. FaEGS1 and FaEGS2 were clustered in the same group clade. The four genes were expressed in all analysed tissues and, in particular, expressed to higher relative expression levels in leaves. The expression of FaEGS1, FaEGS2, and FaEOBII was the highest in large green fruits, and FaMYB10 had the highest expression in red-ripening fruits. The amount of eugenol showed a stage-specific profile. The expression of these four genes was up-regulated by ethephon (ETH), dark, drought, heat, and salt treatments accompanied by the increase of eugenol production. Concentration and timing of cadmium treatment affected gene expression. Cadmium inhibited the expression of FaEGS1 and FaEOBII, but significantly promoted the expression of FaEGS2 and FaMYB10 and eugenol content. The results provide a basis for elucidating the role of these genes in response to abiotic stresses, and regulating the accumulation of eugenol, an important constituent of volatile compounds in many economically important and aromatic plants.