The epigenetic origin of life history transitions in plants and algae

Abstract

Plants and algae have a complex life history that transitions between distinct life forms called the sporophyte and the gametophyte. This phenomenon—called the alternation of generations—has fascinated botanists and phycologists for over 170 years. Despite the mesmerizing array of life histories described in plants and algae, we are only now beginning to learn about the molecular mechanisms controlling them and how they evolved. Epigenetic silencing plays an essential role in regulating gene expression during multicellular development in eukaryotes, raising questions about its impact on the life history strategy of plants and algae. Here, we trace the origin and function of epigenetic mechanisms across the plant kingdom, from unicellular green algae through to angiosperms, and attempt to reconstruct the evolutionary steps that influenced life history transitions during plant evolution. Central to this evolutionary scenario is the adaption of epigenetic silencing from a mechanism of genome defense to the repression and control of alternating generations. We extend our discussion beyond the green lineage and highlight the peculiar case of the brown algae. Unlike their unicellular diatom relatives, brown algae lack epigenetic silencing pathways common to animals and plants yet display complex life histories, hinting at the emergence of novel life history controls during stramenopile evolution.

Gametophyte phase of commercial kelps, the potential food supplements for essential fatty acids and n‐3 polyunsaturated fatty acids

“…From a morphological point of view, the morphology often presents amazing changes in brown algae, resulting in great differences in the level of complexity at the cell, tissue, and organ levels (Chapman, 1945). It has been speculated that the evolution regulated by genes and the environment causes great morphological differences in the life history of alternation generations, which requires further research, but it is certain that the morphological differences are inextricably linked to changes in metabolites (Vigneau & Borg, 2021). Different genders of C. costata have different physiological functions, and normally the female gametophyte presents a larger cell size than the males (Fu et al., 2010).…”

Phenotype stability and dynamics of transposable elements in a strain of the microalga Tisochrysis lutea with improved lipid traits

“…lutea and, more generally, for haptophytes. Nevertheless, knowledge about the epigenetic regulation of TE activity is still limited and appear to differs depending on the microalgal taxa [ 83 , 87 – 90 ]. To our knowledge, no previous studies investigated the effect of UV on the activity of TEs in microalgae.…”

Variation in Thermal Tolerance of the Giant Kelp’s Gametophytes: Suitability of Habitat, Population Quality or Local Adaptation?

“…recent studies suggest that, at least in plants, the epigenetic modifications that are environmentally induced showed a limited meiotic stability (Paszkowski and Grossniklaus, 2011;Wibowo et al, 2016), suggesting that meiotic spores may not be an adequate carrier of the maternal effect on the gametophytic stage; iv. brown algae seem to lack the capacity to methylate DNA (Vigneau and Borg, 2021). We therefore might expect an overall low incidence of parental effects.…”