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Aggravation of photoinhibition during variegated leaf development in Actinidia kolomikta (Rupr. & Maxim.) Maxim.

Wang, Zhen-Xing, Sun, Dan, Zhao, Ying, Yang, Yi-Ming, Ai, Jun, Qin, Hong-Yan, Jiang, Chuang-Dao
Environmental and experimental botany 2018 v.148 pp. 176-183
Actinidia kolomikta, absorption, anthocyanins, chlorophyll, gas exchange, hydrogen peroxide, leaf development, leaves, malondialdehyde, photochemistry, photoinhibition, photosystem II, spectral analysis
Variegated leaves of Actinidia kolomikta (Rupr. & Maxim.) Maxim. are white, pink and pale green according to the order of leaf development, respectively. However, the pale-green leaves are the most sensitive to high-light stress. To clarify the photoinhibitory mechanism in pale-green leaves, we investigated leaf pigment, spectral properties, gas exchange and chlorophyll fluorescence. During variegated leaf development, the chlorophyll content and light absorption increased rapidly, but only pink leaves contained higher anthocyanin contents. With increasing light absorption, the photosynthetic capacity and the actual quantum yield of photosystem II (PSII) in variegated leaves increased slightly, while the non-photochemical quenching (NPQ) significantly decreased. Under high-light conditions, the maximum quantum yield of PSII photochemistry in white and pink leaves decreased less, while in pale-green leaves it decreased significantly together with a substantial increase in malonaldehyde (MDA) and hydrogen peroxide (H2O2) levels. Therefore, during variegated leaf development, although the light absorption increased significantly in pale-green leaves, the photosynthetic capacity and thermal dissipation were not significantly enhanced, which may result in serious photoinhibition under high-light conditions.