不同水陆生境下入侵种喜旱莲子草表型可塑性变异的发生与植物激素信号的关系

Abstract

喜旱莲子草(Alternanthera philoxeroides (Mart.) Griseb.)是一种恶性入侵植物，依赖极强的表型可塑性成功入侵不同水陆生境。为揭示喜旱莲子草响应生境条件变异发生表型可塑性反应的相关信号通路，作者在模拟不同水陆生境的同质园环境下，利用多种植物激素及其抑制剂设计了一系列“正反”处理实验，比较喜旱莲子草形态特征可塑性变异式样在不同处理下的异同。结果表明：从陆地到水生环境后，喜旱莲子草响应环境变异发生快速的节间伸长、髓腔扩大的适应性可塑性反应；节间伸长和髓腔扩大的形态可塑性反应都需要乙烯的参与，而赤霉素仅参与节间伸长的形态可塑性反应，生长素仅参与髓腔扩大的形态可塑性反应。这些结果说明，环境因子主要通过乙烯、赤霉素和生长素信号通路介导了水陆生境变异下喜旱莲子草表型可塑性变异的发生。 Alternanthera philoxeroides (Mart.) Griseb. is a malignant invasive weed in China. It has successfully invaded both aquatic and terrestrial habitats through phenotypic plasticity. To understand the signaling pathways potentially responsible for the development of phenotypically plastic variation in response to changing environment, A. philoxeroides were treated by a variety of phytohormones and their inhibitors under two common gardens, which respectively simulated the typical aquatic and terrestrial habitats colonized by A. philoxeroides in natural environments, then morphological variations among plants under different treatments were compared. The results showed that pond habitat promoted rapid elongation of internodes and further expansion of stem pith cavity in A. philoxeroides, contributing to their adaptation to submergence; ethylene was involved in both internode elongation and stem pith cavity expansion process, gibberellin was only involved in the internode elongation process, and auxin was only involved in the stem pith cavity expansion process. These results suggest that the ethylene, gibberellin and auxin signaling pathways are potentially responsible for the development of phenotypically plastic variation of A. philoxeroides in responding to changing water habitat.