Non-stressful temperature changes affect transgenerational phenotypic plasticity across the life cycle of Arabidopsis thaliana plants.

BACKGROUND AND AIMS: Plants respond in a plastic manner to seasonal changes, often resulting in adaptation to environmental variation. Although much is known about how seasonality regulates developmental transitions within generations, transgenerational effects of non-stressful environmental changes are only beginning to be unveiled. This study aimed to evaluate the effects of ambient temperature changes on the expression of transgenerational plasticity in key developmental traits of Arabidopsis thaliana plants. METHODS: We grew Columbia-0 plants in two contrasting temperature environments (18 and 24 °C) during their whole life cycles, or the combination of those temperatures before and after bolting (18-24 and 24-18 °C) across two generations. We recorded seed germination, flowering time and reproductive biomass production for the second generation, and seed size of the third generation. KEY RESULTS: The environment during the whole life cycle of the first generation of plants, even that experienced before flowering, influenced the germination response and flowering time of the second generation. These effects showed opposing directions in a pattern dependent on the life stage experiencing the cue in the first generation. In contrast, the production of reproductive biomass depended on the immediate environment of the progeny generation. Finally, the seed area of the third generation was influenced positively by correlated environments across generations. CONCLUSIONS: Our results suggest that non-stressful environmental changes affect the expression of key developmental traits across generations, although those changes can have contrasting effects depending on the parental and grandparental life stage that perceives the cue. Thus, transgenerational effects in response to non-stressful cues might influence the expression of life-history traits and potential adaptation of future generations.

Role of the RNA-directed DNA Methylation pathway in the regulation of maternal effects in Arabidopsis thaliana seed germination.

The RNA-directed DNA Methylation pathway (RdDM) influences progeny seed responses to different maternal environments. However, its role in the regulation of early traits in response to non-stressful environmental cues across generations, which can potentially affect life cycle adjustment to seasonal changes, has not been explored in detail. Here we show that the RdDM pathway regulates overall germination but, in some instances, it does so depending on the early life maternal environment. Altogether, our results support that epigenetic memory (mediated by RdDM) is regulating intergenerational transmission of environmental information to affect the phenotypic expression of early traits.