Leaf morphological and photosynthetic differences among four chemotypes of Cinnamomum camphora in different seasons

Abstract Linalool chemotype (LnL), eucalyptol chemotype (EuL), camphor chemotype (CmR) and borneol chemotype (BeL) are 4 main chemotypes of Cinnamomum camphora, an evergreen tree species with great economic and applied value. To facilitate their distinction, cultivation, and utilization, the differences of leaf morphology, photosynthetic abilities and related gene expression between the 4 chemotypes of C. camphora were investigated during spring (April and May), summer (July), and autumn (November). The 4 chemotypes of C. camphora exhibited different leaf morphology. Large leaves were detected in LnL and EuL, which might result from the high expression of the genes related to biosynthesis of brassinosteroids and cytokinins, as well as signal transduction and responses of brassinosteroids and auxins. Thick leaves were detected in EuL and BeL, as the genes related to biosynthesis of cutin, suberin and waxes were highly expressed. Among the 4 chemotypes, EuL and CmR showed strong photosynthetic abilities, which resulted from their high photosynthetic pigment content, photosystem II efficiency and photosynthetic rate, due to the high expression of the genes involving in photosynthetic pigment biosynthesis, photosynthetic electron transport, ATPase biogenesis, and CO2 fixation.