墨兰‘达摩’叶艺品系光合色素含量、叶绿素荧光特性和叶绿体超微结构的比较

Comparison of Photosynthetic Pigments Content, Chlorophyll Fluorescence Kinetics Parameters and Chloroplast Ultrastructure of Leaf Mutant Cultivars of Cymbidium sinense 'Damo'

墨兰叶色变异品系具有较高的观赏和经济价值,但其叶色变异机理尚不清楚。对墨兰栽培品系‘达摩’正常绿叶及其4个叶色变异(叶艺)品系的叶片光合色素含量和叶绿素荧光动力学参数进行比较,发现叶艺品系叶片黄色区域的总叶绿素和类胡萝卜素含量均小于绿色区域,且叶绿素含量降低更为显著,造成Caro/Chl升高,叶色黄化。叶绿素荧光参数显示叶艺品系叶片黄色区域的F_v/F_m、NPQ值也有相应降低,而qp、Y(Ⅱ)值比绿色区域高,可能与其高比例的叶绿素a和类胡萝卜素含量相关。进一步对叶绿体超微结构进行分析,发现叶艺品系叶片绿色区域叶绿体存在不同程度发育缺陷,而黄色区域的叶绿体退化更为严重,没有完整的叶绿体结构。此外,研究结果显示,叶艺品系叶片绿色区域F_v/F_m值的变化趋势与其叶绿体发育完整程度具有一致性,qp、Y(Ⅱ)值与总叶绿素和类胡萝卜素含量变化趋势一致,但黄色区域并不呈现出这种相关性,可能与叶绿体发育严重受损有关。

Though leaf mutant cultivars of Cymbidium sinense ‘ Damo＇ have a high ornamental and economic value, the mechanism of mutant is still unknown. The photosynthetic pigments content, chlorophyll fluorescence kinetics parameters of ‘Green Damo＇ and four leaf mutants of ‘Damo＇ were compared and analyzed. The content of carotenoid and chlorophyll on the yellow part of the mutant leaves were significantly less than that of the green part respectively. The content of chlorophyll was much lower, leading to the increase of Caro/Chl ratio and leaf yellowing. The determination of chlorophyll fluorescence kinetics parameters showed F_v/F_mand NPQ values on the yellow parts were lower accordingly, while qp and Y（Ⅱ） values were higher, indicating that the result was related to the high ratio of the chlorophyll a and carotenoid. The further observation of chloroplast ultrastructure observation found that the integrity degrees of chloroplast development on the green part of different mutants varied and chloroplast structures were damaged more severely on the yellow part. The result showed F_v/F_mvalues of green parts went with the integrity degrees of chloroplast development. qp and Y（Ⅱ） values were consistent with content of chlorophyll and carotinoid. However, F_v/F_m, qp and Y（Ⅱ） values on the yellow part did not show such a consistency, indicating that the result may arise from the severely damaged chloroplast structure on the yellow part of the mutant leaves.