夏季南亚热带森林演替中后期优势种幼叶花色素苷的光保护作用

Photoprotection of Anthocyanins in Young Leaves of Dominant Tree Species at Mid- and Late-successional Stages of Low Subtropical Forest in Summer

摘要:

为探讨夏季南亚热带森林演替过程中优势树种幼叶的光保护机制，以演替中期优势树种木荷（Schima superba）、黧蒴（Castanopsis fissa）、锥栗（C. chinensis）和演替后期优势种华润楠（Machilus chinensis）、厚壳桂（Cryptocarya chinensis）、黄果厚壳桂（C. concinna）为材料，分析了2种生长光强（全光照和30%全光照）下6种优势种幼叶和成熟叶的叶片表型、光合色素含量、花色素苷含量、抗氧化能力、类黄酮含量、总酚含量和最大量子产量（Fv/Fm）恢复效率间的差异。结果表明，两个演替阶段幼叶的叶绿素含量（Chl a+b）、Chl a/b比成熟叶低，但光保护物质比成熟叶多；演替中期幼叶的花色素苷含量和总抗氧化能力比演替后期的高，而类黄酮和总酚含量比演替后期的低；全光照下幼叶的总酚、类黄酮、总抗氧化能力及Fv/Fm恢复效率都要比30%全光照的高，并且含有花色素苷的幼叶恢复得更快。因此，植物的光合能力与自身的光保护潜力成反比关系，演替中期优势种幼叶的光保护在很大程度上是因为花色素苷的积累而演替后期优势种是因为自身抗氧化物质（类黄酮、总酚）的共同作用。

Abstract:

In order to investigate the photoprotection mechanism in young leaves of dominant tree species of subtropical forest in summer, three mid-successional species, i.e. Schima superba, Castanopsis fissa and C. chinensis, and three late-successional species, i.e. Machilus chinensis, Cryptocarya chinensis and C. concinna, grown on 100% (FL) and 30% (LL) of full sunlight, respectively, the leaf phenotype, anthocyanins content, photosynthetic pigment content, antioxidant capacity, flavonoids content, phenols content and restoration efficiency of the maximum photochemical efficiency (Fv/Fm) of young or mature leaves of six dominant trees were analyzed. The results showed that young leaves of dominant tree species at two successional stages had lower chlorophyll content (Chl a+b) and Chl a/b than mature leaves, but light protects substances were more than mature leaves. Young leaves of mid-successional species exhibited higher anthocyanins content and total antioxidant capacity (TCA) but lower contents of flavonoids and total phenols than those in late-successional species. Young leaves of both successional species grown in FL demonstrated higher contents of anthocyanins, phenols, flavonoids, TCA and restoration capability of Fv/Fm than those grown in LL. In addition, Fv/Fm of young leaves with anthocyanins restored faster after exposed to weak light. Therefore, it was suggested that photosynthetic capacity is negative correlated with photoprotection potential. Anthocyanins play an important role in photoprotection of young leaves in mid-successional species, whereas young leaves of late-successional species are mainly photoprotected by antioxidant compounds (flavonoids, total phenols).