Epigenetic variation within Phragmites australis among lineages, genotypes, and ramets

Abstract

Epigenetics is likely an important factor in morphological and physiological acclimation, phenotypic plasticity, and potentially ecological dynamics such as invasiveness. We propose that Phragmites australis is an ideal model species for studies of epigenetics as a factor in plant invasions and ecology due to natural clonal replication (controlling for genetic variation) and the co-occurrence of subspecies with distinct life history strategies such as differences in invasiveness. In earlier work, genotypes and constituent clonal ramets were identified using microsatellite markers. In this pilot study, we screened the same ramets for epigenetic variation with Methylation-Sensitive AFLPs (MS-AFLPs), a modified type of AFLP dependent on differentially methylation-sensitive restriction enzymes. We found a significant difference in epigenetic signatures between introduced and native subspecies, and found that introduced P. australis demonstrated more epigenetic variation than their native counterparts. In both subspecies we observed moderate variation between genotypes relative to the higher degree of epigenetic variation found within genotypes (among ramets), suggesting that epigenotype may be more closely aligned with microhabitat than within-subspecies genotype. Finally, we observed potential epigenetic variation by site. This is the first study to investigate natural variation in DNA methylation patterns of P. australis and establishes the baseline in our understanding of the ecological relevance of epigenetics in this species.