title: Gene Expression Reaction Norms Unravel the Molecular and Cellular Processes Underpinning the Plastic Phenotypes of Alternanthera Philoxeroides in Contrasting Hydrological Conditions.
abstract: Alternanthera philoxeroides is an amphibious invasive weed that can colonize both aquatic and terrestrial habitats. Individuals growing in different habitats exhibit extensive phenotypic variation but little genetic differentiation. Little is known about the molecular basis underlying environment-induced phenotypic changes. Variation in transcript abundance in A. philoxeroides was characterized throughout the time-courses of pond and upland treatments using RNA-Sequencing. Seven thousand eight hundred and five genes demonstrated variable expression in response to different treatments, forming 11 transcriptionally coordinated gene groups. Functional enrichment analysis of plastically expressed genes revealed pathway changes in hormone-mediated signaling, osmotic adjustment, cell wall remodeling, and programmed cell death, providing a mechanistic understanding of the biological processes underlying the phenotypic changes in A. philoxeroides. Both transcriptional modulation of environmentally sensitive loci and environmentally dependent control of regulatory loci influenced the plastic responses to the environment. Phenotypic responses and gene expression patterns to contrasting hydrological conditions were compared between A. philoxeroides and its alien congener Alternanthera pungens. The terricolous A. pungens displayed limited phenotypic plasticity to different treatments. It was postulated based on gene expression comparison that the interspecific variation in plasticity between A. philoxeroides and A. pungens was not due to environmentally-mediated changes in hormone levels but to variations in the type and relative abundance of different signal transducers and receptors expressed in the target tissue.
authors.affiliation: Center for Evolutionary Biology and Institute of Biodiversity Science, Fudan University Shanghai, China ; Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai Chenshan Botanical Garden Shanghai, China.
authors.forename: Lexuan
authors.initials: L
authors.lastname: Gao
authors.affiliation: School of Ecology and Environmental Sciences, Institute of Ecology and Geobotany, Yunnan University Kunming, China.
authors.forename: Yupeng
authors.initials: Y
authors.lastname: Geng
authors.affiliation: Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai Chenshan Botanical Garden Shanghai, China.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Yang
authors.affiliation: Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai Chenshan Botanical Garden Shanghai, China.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Center for Evolutionary Biology and Institute of Biodiversity Science, Fudan University Shanghai, China.
authors.forename: Ji
authors.initials: J
authors.lastname: Yang
keywords: Alternanthera philoxeroides; genomic reaction norm; molecular processes; phenotypic plasticity; transcriptional plasticity