关键词: 光合色素, 气体交换参数, 光响应曲线, 叶绿素荧光, 叶绿体超微结构, 白化转绿, 花叶矢竹

Abstract: [Objective] The green-revertible pattern of leaves of albino Pseudosasa japonica f. akebonosuji are complex.The white parts of the whole white leaf or stripe leaf gradually turn green, and the degree of chloroplast development and the rate of return-green are different in the various leaves. The chlorophyll relative content (SPAD) of the leaves with different green degrees was measured with the non-invasive measurement method, by which we investigated the relationship among chloroplast ultrastructure, photosynthetic pigment content and photosynthetic characteristic of P.japonica f.akebonosuji. This study aimed to shed light to the further study of the green-revertible mechanism and the breeding of ornamental bamboo.[Method] The leaves of P.japonica f. akebonosuji with different green degrees were used in this study, and the mature green leaves served as the control (CK). The leaf samples were divided in to 6 stages according to the green degree, 0, 10%, 30%, 50%, 70% and 90%.The photosynthetic pigment content, photosynthetic characteristics and chlorophyll fluorescence parameters and chloroplast ultrastructure of leaves in each stage were investigated to explore the changes of physiological and biochemical levels in the green-revertible period.[Result]The results showed that albino leaves of Pseudosasa japonica f.akebonosuji had low chlorophylla and chlorophyllb content.Photosynthetic pigment content increased when the white leaves return to green. The chlorophylla, chlorophyllb, total chlorophyll and carotenoid content of the completely returned to green leaves were 87.02%, 98.20%, 89.37%, 85.02% of the natural green leaves,respectively. The Chlorophyllb content of the completely returned to green leaves reached the level of green leaves, but the other pigments didn't. The albino leaves had no photosynthesis. The net photosynthetic rate of the return-green leaves increased significantly, the stomatal conductance became steady in the later stage of regaining green, and the intercellular CO₂ concentration decreased significantly, indicating that the change of photosynthetic rate was affected by non-stomatal factors. The light saturation point of green-revertible leaves increased, the light compensation point decreased and the dark respiration rate was not significantly different from those of the natural green leaf. The rate of apparent quantum yield in 90% green-regaining leaves was 78.66% of the normal leaves. The F_o and NPQ increased firstly and then decreased, but F_v/F_m, Y(Ⅱ) and ETR were significantly raised, indicating when the content of photosynthetic pigment increased, the light-harvesting ability and photochemical conversion efficiency in PSⅡ reaction center were gradually restored. The change of q_P in the early stage of green-regaining progress was slow, and the change of chlorophylla/b reaction center was not affected by the green-regaining process. The chloroplast ultrastructural changed significantly. The chloroplast inner membrane structure of the regaining green leaves was gradually returned to normal, while the lamellar structure of chloroplast in green leaves was clear and uniform.[Conclusion]The accumulation of photosynthetic pigments and reconstruction of thylakoid membrane are the two important non-stomatal factors leading to the recovery of photosynthetic capacity in the green revertible leaves.

Key words: photosynthetic pigments, gas exchange parameters, light response curve, chlorophyll fluorescence, chloroplast ultrastructure, green-revertible, Pseudosasa japonica f.akebonosuji