Format: ORAL

Jos Carlos del Valle1, Justen B. Whittall2, M. Luisa Buide3, Eduardo Narbona3

1 Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain 2 Department of Biology, Santa Clara University, Santa Clara, California, United States of America 3 Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Seville, Spain

Besides the predominant role of pollinators in floral evolution, it has been suggested that the selective pressures exerted by abiotic agents may also contribute to variability in flower color. In the past ten years, we used the shore campion (Silene littorea) as a model species to develop studies aimed at gaining a better understanding of modifications of flower color driven by these selection agents, mainly focusing on the effect of solar, and more specifically in the UV light. We used different approaches to unveil color variation in this species, such as common garden experiments, transcriptomic and biochemical studies. Our results have highlighted that flower color in S. littorea is influenced to some extent by sunlight and UV radiation. However, the specific regulation of anthocyanin production in petals, the main pigments responsible for the flower color in this species, may reduce drastic changes on that trait, presumably due to its importance for pollinators. This is manifested in the lower plasticity observed in anthocyanin biosynthesis in petals compared to vegetative tissues. Additionally, transcriptomic and biochemical analyses have evidenced that petal pigmentation is tissue-specific regulated, resulting even in the occurrence of individuals with white flowers lacking anthocyanins without hindering anthocyanin accumulation in other tissues. Pollinator attraction seems to be at least partially favored by the presence of petal anthocyanins, although white-flowered plants can overcome this limitation by utilizing their mixed mating system and reproducing through autonomous selfing. Finally, the rarity of plants lacking anthocyanins in both vegetative and reproductive tissues suggest that anthocyanins in photosynthetic tissues are the targets of non-pollinator mediated selection. In conclusion, we suggest that environmental stressors may drive anthocyanin accumulation in the whole plant, although it may be limited in petals, at least in S. littorea. Future research will incorporate further transcriptomic and biochemical analyses.