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Whilst transgenerational effects (TGE) of abiotic conditions are becoming generally accepted in plants, those of biotic interactions remain largely unexplored. We therefore investigated the influence of TGE due to arbuscular mycorrhiza, the most widespread mutualistic interaction of plants with microorganisms, on clonal and sexual offspring of Fragaria vesca. We hypothesized that the ecological and evolutionary significance of TGE will vary between clonal and sexual offspring based on mycorrhizal status and phosphorus (P) availability experienced by the parent. In a two‐generation greenhouse experiment, parental plants were exposed to full‐factorial combinations of mycorrhizal status and high or low P availability. TGE on mycorrhiza establishment and plant performance were evaluated in their clonal and sexual offspring, which experienced the parental or all non‐parental environments. Consistently in both generations, mycorrhiza improved plant growth at low P availability, but had no or even negative effect at high P availability, concomitantly with decreased root colonization by the arbuscular mycorrhizal (AM) fungus. TGE due to mycorrhiza was generally stronger in sexually derived offspring, both on mycorrhiza formation and plant growth. In sexual offspring, parental mycorrhizal status was adaptive if the offspring's mycorrhizal status was of disadvantage: for mycorrhizal offspring growing in high P availability and for non‐mycorrhizal offspring at low P availability. Synthesis: Our results suggest that clonal and sexual reproduction are under different evolutionary pressures, leading to the development of stronger TGE mechanisms in response to mycorrhizal symbiosis in the latter. The complexity of the observed effects highlights the need for disentangling the mechanisms contributing to the TGE in clonal and sexual reproduction. Our study underlines the importance of considering reproductive strategies and the interplay between environmental factors and TGE in understanding the ecological and evolutionary dynamics of plant–symbiotic interactions. [ABSTRACT FROM AUTHOR]

Summary: Due to the accelerating climate change, it is crucial to understand how plants adapt to rapid environmental changes. Such adaptation may be mediated by epigenetic mechanisms like DNA methylation, which could heritably alter phenotypes without changing the DNA sequence, especially across clonal generations. However, we are still missing robust evidence of the adaptive potential of DNA methylation in wild clonal populations.Here, we studied genetic, epigenetic and transcriptomic variation of Fragaria vesca, a predominantly clonally reproducing herb. We examined samples from 21 natural populations across three climatically distinct geographic regions, as well as clones of the same individuals grown in a common garden.We found that epigenetic variation was partly associated with climate of origin, particularly in non‐CG contexts. Importantly, a large proportion of this variation was heritable across clonal generations. Additionally, a subset of these epigenetic changes affected the expression of genes mainly involved in plant growth and responses to pathogen and abiotic stress. These findings highlight the potential influence of epigenetic changes on phenotypic traits.Our findings indicate that variation in DNA methylation, which can be environmentally inducible and heritable, may enable clonal plant populations to adjust to their environmental conditions even in the absence of genetic adaptation. [ABSTRACT FROM AUTHOR]

The high rate of climate change may soon expose plants to conditions beyond their adaptation limits. Clonal plants might be particularly affected due to limited genotypic diversity of their populations, potentially decreasing their adaptability. We therefore tested the ability of a widely distributed predominantly clonally reproducing herb (Fragaria vesca) to cope with periods of drought and flooding in climatic conditions predicted to occur at the end of the twenty-first century, i.e. on average 4 °C warmer and with twice the concentration of CO2 in the air (800 ppm) than the current state. We found that F. vesca can phenotypically adjust to future climatic conditions, although its drought resistance may be reduced. Increased temperature and CO2 levels in the air had a far greater effect on growth, phenology, reproduction, and gene expression than the temperature increase itself, and promoted resistance of F. vesca to repeated flooding periods. Higher temperature promoted clonal over sexual reproduction, and increased temperature and CO2 concentration in the air triggered change in expression of genes controlling the level of self-pollination. We conclude that F. vesca can acclimatise to predicted climate change, but the increased ratio of clonal to sexual reproduction and the alteration of genes involved in the self-(in)compatibility system may be associated with reduced genotypic diversity of its populations, which may negatively impact its ability to genetically adapt to novel climate in the long-term. [ABSTRACT FROM AUTHOR]

The phenotypes of plants can be influenced by the environmental conditions experienced by their parents. However, there is still much uncertainty about how common and how predictable such parental environmental effects really are. We carried out a comprehensive experimental test for parental effects, subjecting plants of multiple Arabidopsis thaliana genotypes to 24 different biotic or abiotic stresses, or combinations thereof, and comparing their offspring phenotypes in a common environment. The majority of environmental stresses caused significant parental effects, with -35% to +38% changes in offspring fitness. The expression of parental effects was strongly genotype-dependent, and multiple environmental stresses often acted nonadditively when combined. The direction and magnitude of parental effects were unrelated to the direct effects on the parents: Some environmental stresses did not affect the parents but caused substantial effects on offspring, while for others, the situation was reversed. Our study demonstrates that parental environmental effects are common and often strong in A. thaliana, but they are genotype-dependent, act nonadditively, and are difficult to predict. We should thus be cautious with generalizing from simple studies with single plant genotypes and/or only few individual environmental stresses. A thorough and general understanding of parental effects requires large multifactorial experiments., (© 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.)