Ipomoea pes-caprae (Convolvulaceae), a pantropical plant with sea-drifted seeds, is found globally in the littoral areas of tropical and subtropical regions. Unusual long-distance seed dispersal has been believed to be responsible for its extraordinarily wide distribution; however, the actual level of inter-population migration has never been studied. To clarify the level of migration among populations of I. pes-caprae across its range, we investigated nucleotide sequence variations by using seven low-copy nuclear markers and 272 samples collected from 34 populations that cover the range of the species. We applied coalescent-based approaches using Bayesian and maximum likelihood methods to assess migration rates, direction of migration, and genetic diversity among five regional populations. Our results showed a high number of migrants among the regional populations of I. pes-caprae subsp. brasiliensis, which suggests that migration among distant populations was maintained by long-distance seed dispersal across its global range. These results also provide strong evidence for recent trans-oceanic seed dispersal by ocean currents in all three oceanic regions. We also found migration crossing the American continents. Although this is an apparent land barrier for sea-dispersal, migration between populations of the East Pacific and West Atlantic regions was high, perhaps because of trans-isthmus migration via pollen dispersal. Therefore, the migration and gene flow among populations across the vast range of I. pes-caprae is maintained not only by seed dispersal by sea-drifted seeds, but also by pollen flow over the American continents. On the other hand, populations of subsp. pes-caprae that are restricted to only the northern part of the Indian Ocean region were highly differentiated from subsp. brasiliensis. Cryptic barriers that prevented migration by sea dispersal between the ranges of the two subspecies and/or historical differentiation that caused local adaptation to different environmental factors in each region could explain the genetic differentiation between the subspecies.

Plants are sessile organisms that need to adapt to constantly changing environmental conditions. Unpredictable climate change places plants under a variety of abiotic stresses. Studying the regulation of stress-responsive genes can help to understand plants’ ability to adapt to fluctuating environmental conditions. Changes in epigenetic marks such as histone modifications and DNA methylation are known to regulate gene expression by their dynamic variation in response to stimuli. This can then affect their phenotypic plasticity, which helps with the adaptation of plants to adverse conditions. Epigenetic marks may also provide a mechanistic basis for stress memory, which enables plants to respond more effectively and efficiently to recurring stress and prepare offspring for potential future stresses. Studying epigenetic changes in addition to genetic factors is important to better understand the molecular mechanisms underlying plant stress responses. This review summarizes the epigenetic mechanisms behind plant responses to some main abiotic stresses.

Being sessile organisms, plants show a high degree of developmental plasticity to cope with a constantly changing environment. While plasticity in plants is largely controlled genetically, recent studies have demonstrated the importance of epigenetic mechanisms, especially DNA methylation, for gene regulation and phenotypic plasticity in response to internal and external stimuli. Induced epigenetic changes can be a source of phenotypic variations in natural plant populations that can be inherited by progeny for multiple generations. Whether epigenetic phenotypic changes are advantageous in a given environment, and whether they are subject to natural selection is of great interest, and their roles in adaptation and evolution are an area of active research in plant ecology. This review is focused on the role of heritable epigenetic variation induced by environmental changes, and its potential influence on adaptation and evolution in plants.

Summary: Mangroves are adapted to harsh environments, such as high ultraviolet (UV) light, low nutrition, and fluctuating salinity in coastal zones. However, little is known about the transcriptomic and epigenomic basis of the resilience of mangroves due to limited available genome resources. We performed a de novo genome assembly and in natura epigenome analyses of the mangrove Bruguiera gymnorhiza, one of the dominant mangrove species. We also performed the first genome‐guided transcriptome assembly for mangrove species. The 309 Mb of the genome is predicted to encode 34 403 genes and has a repeat content of 48%. Depending on its growing environment, the natural B. gymnorhiza population showed drastic morphological changes associated with expression changes in thousands of genes. Moreover, high‐salinity environments induced genome‐wide DNA hypermethylation of transposable elements (TEs) in the B. gymnorhiza. DNA hypermethylation was concurrent with the transcriptional regulation of chromatin modifier genes, suggesting robust epigenome regulation of TEs in the B. gymnorhiza genome under high‐salinity environments. The genome and epigenome data in this study provide novel insights into the epigenome regulation of mangroves and a better understanding of the adaptation of plants to fluctuating, harsh natural environments.

In long‐lived tree populations, when environmental change outpaces rates of evolutionary adaptation, plasticity in traits related to stress tolerance, dormancy, and dispersal may be vital for preventing extinction. While a population's genetic background partly determines its ability to adapt to a changing environment, so too do the many types of epigenetic modifications that occur within and among populations, which vary on timescales orders of magnitude faster than the emergence of new beneficial alleles. Consequently, phenotypic plasticity driven by epigenetic modification may be especially critical for sessile, long‐lived organisms such as trees that must rely on this plasticity to keep pace with rapid anthropogenic environmental change. While studies have reported large effects of DNA methylation, histone modification, and non‐coding RNAs on the expression of stress‐tolerance genes and resulting phenotypic responses, little is known about the role of these effects in non‐model plants and particularly in trees. Here, we review new findings in plant epigenetics with particular relevance to the ability of trees to adapt to or escape stressors associated with rapid climate change. Such findings include specific epigenetic influences over drought, heat, and salinity tolerance, as well as dormancy and dispersal traits. We also highlight promising findings concerning transgenerational inheritance of an epigenetic ‘stress memory’ in plants. As epigenetic information is becoming increasingly easy to obtain, we close by outlining ways in which ecologists can use epigenetic information better to inform population management and forecasting efforts. Understanding the molecular mechanisms behind phenotypic plasticity and stress memory in tree species offers a promising path towards a mechanistic understanding of trees' responses to climate change.

Epigenetic mechanisms, including DNA methylation, histone modifications, and Noncoding RNAs, play a critical role in enabling plants to adapt to environmental changes without altering their DNA sequence. These processes dynamically regulate gene expression in response to diverse stressors, making them essential for plant resilience under changing global conditions. This review synthesises research on tropical and subtropical plants—species naturally exposed to extreme temperatures, salinity, drought, and other stressors—while drawing parallels with similar mechanisms observed in arid and temperate ecosystems. By integrating molecular biology with plant ecology, this synthesis highlights how tropical plants provide valuable models for understanding resilience strategies applicable across broader plant taxa. This review underscores the potential of epigenetic mechanisms to inform conservation strategies and agricultural innovations aimed at bolstering plant resilience in the face of climate change.