Epigenetic Mechanism Of Clonal Plant Habitat Selection In Heterogeneous Pb-Contaminated Environment

In heterogeneous environments,clonal plants can enhance their competitiveness through habitat selection behavior,but there are few researches on the mechanism of clonal plant habitat selection.Environmental stimuli can induce epigenetic changes in plants,resulting in epigenetic memory.The clonal plant can transmit the phenotypic plasticity variation regulated by epigenetic memory to the offspring ramets by transgenerational effects,so that it can better cope with environmental changes.Therefore,epigenetic memory is likely to play an important regulatory role in the process of clonal plant's habitat selection.In this study,the clonal plant Duchesnea indica was placed in six different environments,that was: two kinds of mother ramets' condition(Pb-contaminated and un-contaminated),and three offspring ramets' condition(un-contaminated,heterogeneous Pb-un-contaminated,and Pb-un-contaminated).By measuring the growth parameter(ramet number,stolon length,aboveground and underground biomass)of clonal genet in different treatments to determine the habitat selection strategy for clonal plants in a heterogeneous Pb-contaminated environment.And based on this,treatment of the mother ramet with methylation reagents that maintain or weaken memory,DNA methylation changes of mother and offspring ramets in different habitats was detected with MSAP molecular marker technology,to determine the roles of epigenetic memory formed by the mother ramet in the Pb contaminated environment and its transgenerational effectson the process of clonal plant's habitat selection.The results are as follows:(1)The epigenetic memory could be induced by Pb-stressed experience of mother ramet by the decrease of DNA methylation level.(2)Clonal integration could affect the epigenetic changes of the mother ramet.The methylation level of the mother ramets with clonal integration was higher than that of the mother ramets without integration.In addition,the habitats of the offspring ramets also affected the epigenetic changes of the mother ramet and the habitats with low Pb contaminated levels(homogeneity without Pb contaminated and heterogeneous Pb contaminated)was higher than that of the highly Pb contaminated habitat(homogeneous Pb contaminated);(3)The epigenetic memory of Pb contamination formed by the mother ramet did not cross-generation transfer successfully at least between the offspring ramets generations we monitored;(4)Epigenetic memory affected the habitat selection behavior of clonal plants.In the habitats where both mother and offspring ramets are contaminated,after the epigenetic memory of the mother ramet is weakened,the biomass,total ramets number,and the length of the longest branch were increased significantly.It can be seen that the epigenetic memory of Pb contaminated environment in mother ramet influenced the habitat selection strategy of clonal plant by shortened stolons,reduced biomass,and ramets number.In brief,Pb-contaminated environment can induce epigenetic memory of mother ramet by the change of DNA methylation level in clonal plant,and this epigenetic modification can regulate the phenotypic plasticity of clonal ramet,thus enabling clonal plants to better cope with environmental changes.The results of this study will help us to fully understand the ecological adaptation strategies and mechanisms of clonal plants.