| Alternanthera philoxeroides is an invasive weed that exhibit extensive phenotypic plasticity and strong tolerance to habitat stress, but shows very little genetic variation within populations in China. A lot of evidences have proved that the reasons why plant response to stress quickly, generate phonotype variation and even pass the variation to the offspring are closely associated with epigenetic mechanisms. DNA methylation is an important epigenetic mechanism for plant stress response, which has a significant relationship with gene expression and transposon regulation. The existing research have showed that alligator weed will reprogramming the DNA methylation in the pond and upland common garden experiment, and show the DNA methylation specificity in development stages and organs of plant genome. However, we know little about the stability of stress-induced DNA methylation in alligator weed.Therefore, Kunming and N26genotype were chosen to for the common garden experiment. Generation1plants were under five experimental treatments:pond treatment, salt stress, salicylic acid (SA) application, jasmonic acid (JA) application, and control treatment. All generation2plants were raised in common unstressed environment. Leaf tissue and stem tissue were collected in generation1and generation2plants for the MSAP analysis. All of these were conducted for the research of Stress-induced DNA methylation changes and their heritability in asexual Alternanthera philoxeroides. The results were show as the following:1) Stress can trigger DNA methylation changes in alligator weed, and different treatment can trigger different DNA methylation pattern. Comparing different treatment group with the control group reveals that more methylation changes occurred in each of the, water, salt, JA and SA groups in generation1. Based on presence/absence scores of25polymorphic methylation-sensitive amplified fragment length polymorphism markers, different treatment show different DNA methylation pattern through analyze of variation (ANOVA). 2) The methylation modifications were faithfully transmitted to offspring, and the DNA methylation pattern in generation1have different inheritance through different modes of reproduction. About50%DNA methylation observed in Kunming genotype generation1were transmitted to offspring. The research found that no matter the leaf tissue or stem tissue, the DNA methylation pattern still exists in the generation2reproduce from stem fragment, but disappear in the generation2reproduce from root fragment.3) DNA methylation response to same stress varied significantly among genotypes. There is no DNA methylation divergence between treatment and controls for the N26genotype generation1. And all of the changed happened in G1were reverted to consensus. Which differ significantly from the Kunming genotype.These results show the following. Stress-induced methylation changes are common and are heritable. Stress can trigger DNA methylation patterns between treatment and controls, and the patterns can be transmitted to the offspring. This highlights the potential of epigenetic inheritance to play an independent role in evolutionary processes. |
