表型可塑性指同一基因型对不同环境条件应答产生不同表型的特性，是生物适应异质环境的一条重要途径；与此同时，可塑性本身也被看作是对环境变异性的一种适应策略，不同物种、种群乃至不同基因型对环境变化的敏感性、发生可塑性变异的能力不尽相同。哪些因素、通过什么途径影响“可塑性”的表达和进化是目前普遍关注、但缺乏实证研究的科学问题。喜旱莲子草（Alternanthera philoxeroides）与刺花莲子草（A. pungens）是同属近缘种，但表型可塑性变异水平差异显著。前期我们已对喜旱莲子草表型可塑性变异的特点及相关分子基础进行了系列研究，初步揭示了与可塑性变异相关联的基因及其作用机制。在本项目中，我们拟对两个近缘种在不同水陆环境中表型可塑性变异的式样、变异水平和基因表达动态进行比较，挖掘与种间可塑性反应水平分化相关联的基因，为研究“可塑性”进化的基础和动因提供依据。

Phenotypic plasticity, the ability of a genotype to express different phenotypes across environments, is considered one of the major means for organisms to cope with environmental variability. Meanwhile, phenotypic plasticity is itself an adaptive strategy expected to evolve in heterogeneous environments. Even closely related species and populations with different genotypes may exhibit differences in environmental sensitivity and the patterns and extents of plastic responses. The regulatory factors and mechanisms related to the differentiation of plasticity among species remain largely unknown. Alternanthera philoxeroides and A. pungens are congener species, showing distinct differences in the degree of phenotypic plasticity in response to water availability. A. philoxeroides exhibited a significantly higher degree of plasticity and tolerance to waterlogging than its congener. Previously, we have conducted a series of investigation on the molecular underpinnings underlying the environment-induced plastic phenotypes of A. philoxeroides, and revealed the genes and pathways involved in phenotypically plastic variation. In this study, we aimed to detect the genetic factors associated with the interspecific variation in plasticity between A. philoxeroides and A. pungens, by comparing phenotypic responses to contrasting hydrological conditions and monitoring the change in gene expression patterns between species. Making use of modern comparative techniques to identify molecular determinants potentially responsible for variation in plasticity can provide clues to the evolution of phenotypic plasticity within an explicitly phylogenetic context.