毛竹茎秆叶绿体超微结构及其发射荧光光谱特征

为了探讨毛竹（Phyllostachys pubescens）茎秆的光合特性，以1龄和3龄毛竹为材料，观察了茎秆和叶中叶绿体的超微结构，测定了光合色素含量以及发射荧光光谱。结果表明：茎秆中叶绿体发育完整，其类囊体垛叠程度高于叶，并含有淀粉粒。茎秆中叶绿素总含量、类胡萝卜素及Chla／b含量显著低于叶（FI〈O．05）。茎秆发射荧光光谱在735nm处没有明显的主峰，1龄和3龄毛竹茎秆光系统lI与光系统I的半峰宽比值分别比叶降低了7．0％和11．3％（P〈0．05），峰高比值比叶分别增加了6．5％和18．3％（P〈0．05）。四阶导数光谱在650—800nm波长范围内出现了6个极大值，代表LHCII、CP43、CP47、RCI和ILHCI的发射荧光峰以及PSI和PSII的发射荧光副振峰：其中，茎秆中RCI和LHCI特征发射荧光峰与叶相比有不同程度的红移。表明毛竹茎秆叶绿体通过提高Chlb的相对含量和增加类囊体垛叠以及降低LHCI含量，来适应毛竹茎秆以红光为主的光环境。进而协调激发能在2个光系统间的分配。

Chloroplast Ultrastructure and Emission Fluorescence Spectrum Characteristics for Stems of Phyllostachys pubescens

To reveal the photosynthetic characteristics of stems of Phyllostachys pubescens, we used scanning electron microscopy to observe the chloroplast ultrastructure of stems and leaves and detected the changes in pigment content and emission fluorescence spectra in 1- and 3-year-old plants. The emission fluorescence spectra underwent fourth- derivative analysis with Origin Pro 9.0. Chloroplasts of stems showed numerous lamella and abundant starch grains. The chlorophyll, carotenoid and chlorophyll a/b content was significantly lower in stems than leaves （P〈0.05）. The main peak of emission fluorescence spectrum at 735 nm in stems was absent. The semi-width ratios of PSII and PSI in 1- and 3-year-old stems were significantly reduced by 7.0% and 11.3% （P〈0.05）, respectively, as compared with leaves, whereas the height ratio increased by 6.5% and 18.3% （P〈0.05）, respectively. Fourth-derivative spectra showed 6 fluo- rescence peaks between 650 and 800 nm, representing LHCII, CP43, CP47, RCI, LHCI and PSII-PSI shoulder peaks, respectively. RCI and LHCI in stems showed obvious Stokes shifts as compared with the peaks in leaves. Thus, chloro- plasts in stems of P. pubescens may adapt to far-red light and coordinate the allocation of excitation energy between PSII and PSI by increasing the chlorophyll b relative content and the number of lamella as well as reducing the content of LHCI.