Do Naturally Variegated Leaves have a High Photosynthetic Cost? The Case of Actinidia kolomikta (Rupr. & Maxim.) Maxim

The photosynthetic performance of variegated leaves can be very important in the cultivation and management of variegated plants. Actinidia kolomikta (Rupr. & Maxim.) Maxim. leaves have striking color variation. To clarify the variegated leaf type and photosynthetic cost, we measured leaf structure and ultrastructure, spectral properties, chlorophyll fluorescence and net photosynthetic rate (Pn). The study was conducted in Jilin during spring, summer, and fall in 2013. Leaf anatomy and ultrastructure were observed with light and electron microscopy. Leaf reflectance and pigment content were measured with a Unispec spectrometer and high performance liquid chromatography. Photosynthetic characterization was performed with a photosynthesis system and plant efficiency analyzer. In the palisade tissue of variegated areas, intercellular spaces were found, and cells contained fewer and abnormally developed chloroplasts. Normal chloroplasts were distributed mostly in spongy tissue. The reflectance of the adaxial surface was higher in variegated leaves than in green leaves. The Pn of variegated leaves was 80 to 94% of green leaves, the maximum photosystem II efficiency of the adaxial and abaxial surfaces in variegated leaves was similar to green leaves, and the quantum use efficiency of the abaxial surface was higher than the adaxial surface in variegated leaves. These results show that the photosynthetic performance of variegated leaves was retained well. Thus, variegated leaves are not a limiting factor for cultivation and application in A. kolomikta, and do not need to be removed as parasitic leaves during cultivation and management.