铁皮石斛叶色突变体的叶绿体超微结构、光合色素和叶绿素荧光特性的研究

以铁皮石斛(Dendrobium officinale Kimura et Migo)(‘TP35’)经自然突变的白绿杂色突变体(‘TP-MA’)和太空诱变的绿黄杂色突变体(‘TP-MG’)为材料,研究不同光照强度(0、50、100μmol·m^-2·s^-1)处理后,植株叶片的叶绿体超微结构、光合色素含量以及叶绿素荧光动力学参数的变化规律,并阐明叶色突变体与正常植株光合特性的差异。结果显示,‘TP-MA’和‘TP-MG’的叶绿体形态均发生了一定程度的缺失,且叶绿体分布不均匀、无规则,基粒片层结构不完整且排列疏松,基本与其表型性状相一致。‘TP-MA’光合色素的含量和叶绿素荧光参数F v/F m、ΦPSⅡ及F v′/F m′等显著低于‘TP35’,但非光化学淬灭系数(NPQ和q P)则相对较高;‘TP-MG’的光合色素含量及叶绿素荧光参数均低于‘TP35’,但差异不显著,且对较强的光照(100μmol·m^-2·s^-1)条件具有一定的适应性。研究结果表明不同光强处理后,铁皮石斛叶色突变体的叶绿体结构和光合生理指标均发生了不同程度的变化,且对植株的叶绿素含量及荧光参数产生一定影响,过低和过高的光照强度均不利于植株的正常生长。

Study on chloroplast ultrastructure,photosynthetic pigments,and chlorophyll fluorescence characteristics of leaf color mutants in Dendrobium officinale Kimura et Migo

The naturally mutated white-green chimera mutant (‘TP-MA’) and space-mutated green-yellow chimera mutant ('TP-MG’) of Dendrobium officinale (‘TP35’) were used as research materials. We investigated changes in chloroplast ultrastructure, photosynthetic pigment content, and chlorophyll fluorescence kinetic parameters of leaves after treatment with different light intensities (0, 50, 100 μmol·m^-2·s^-1), and clarified the differences in photo-synthetic characteristics between leaf color mutants and normal plants. Results showed that the chloroplast morphology of ‘TP-MA’ and ‘TP-MG’ both had a certain degree of deletion. The chloroplasts were unevenly distributed and irregular, and the basal layer structure was incomplete and loosely arranged, which was basically consistent with phenotypic traits. The photosynthetic pigment content and chlorophyll fluorescence parameters F_v/F_m， Φ_PSⅡ and F_v'/F_m' of ‘TP-MA’ were significantly lower than those of ‘TP35’, but the chlorophyll quenching coefficients (NPQ and q_P) were relatively higher. The photosynthetic pigment content and chlorophyll fluorescence parameters of ‘TP-MG’ were lower than those of ‘TP35’, but the differences were not significant, and it exhibited a certain adaptability to strong illumination (100 μmol·m^-2·s^-1). Thus, results showed that under different light intensities, the chloroplast structure and photosynthetic physiological indices of the D. officinale mutants changed to varying degrees and had certain effects on the chlorophyll content and fluorescence parameters of the plants. Too low or too high light intensity was not conducive to the normal growth of the plants.