Gong Wei-Chang, Liu Yan-Hong, Wang Chuan-Ming, Chen Ya-Qing, Martin Konrad, Meng Ling-Zeng
College of Life Science & Technology, Honghe University, Mengzi, China.
Institute of Agricultural Sciences in the Tropics, Hans-Ruthenberg-Institute, University of Hohenheim, Stuttgart, Germany.
Front Plant Sci. 2020 Feb 18;11:83. doi: 10.3389/fpls.2020.00083. eCollection 2020.
Delayed greening of young leaves is a ubiquitous and visually striking phenomenon in the tropics. Here, we investigated the potential ecological functions of red coloration patterns in young leaves. To detect any protective function of the red coloration on the young leaves, leaf damage by insect herbivores was recorded in the field. To determine capacity for chemical defense, the concentrations of tannins and anthocyanins were measured in both young and mature leaves. To test the hypothesis that anthocyanins function as photo-protective molecules, chlorophyll content, maximum photochemical efficiency of ( / ), non-photochemical quenching (), and effective quantum yield of ( ) were measured in the field. Phylogenetic relationships were analyzed to test the relationary significance of the occurrence of redness in young leaves. Compared to the coloration in non-red leaves, young red leaves had significant higher anthocyanins and tannins content and lower herbivore damages. Young, red leaves had the lowest / values, which were significantly lower than those of non-red leaves. values in young red leaves were comparable to those of other groups. Although young red leaves had high , these values were significantly lower than those of the other three groups. The results suggest that the red coloration of young leaves protects them from insect herbivory primary by chemical defense through high concentrations of tannins and anthocyanins. Additionally, low / values in young red leaves indicate that anthocyanins might not be functioning as light attenuators to compensate for insufficient photo-protection mediated by . And finally, red coloration in young leaves is predominantly a result of adaptation to heavy herbivory stress but without significant intrinsic phylogenetic relationship of plant species.
幼叶延迟返绿是热带地区普遍存在且视觉上引人注目的现象。在此，我们研究了幼叶红色着色模式的潜在生态功能。为检测红色着色对幼叶的任何保护作用，在田间记录了昆虫食草动物对叶片的损害情况。为确定化学防御能力，测量了幼叶和成熟叶中单宁和花青素的浓度。为检验花青素作为光保护分子发挥作用的假设，在田间测量了叶绿素含量、最大光化学效率（Fv/Fm）、非光化学猝灭（NPQ）和有效量子产量（Y(II)）。分析了系统发育关系以检验幼叶发红现象的关联意义。与非红叶的着色相比，幼红叶中的花青素和单宁含量显著更高，食草动物造成的损害更低。幼红叶的Fv/Fm值最低，显著低于非红叶。幼红叶的NPQ值与其他组相当。尽管幼红叶的Y(II)值较高，但这些值显著低于其他三组。结果表明，幼叶的红色着色主要通过高浓度的单宁和花青素进行化学防御，从而保护它们免受昆虫食草动物的侵害。此外，幼红叶中较低的Fv/Fm值表明花青素可能并非作为光衰减剂来补偿由叶绿素介导的光保护不足。最后一点，幼叶发红主要是对重度食草动物压力适应的结果，而与植物物种没有显著的内在系统发育关系。
