UV radiation increases flavonoid protection but decreased reproduction inSilene littorea

Abstract

15Plants respond to changes in ultraviolet (UV) radiation via morphological and 16 physiological changes. Among the variety of plant UV-responses, the synthesis of UV-17 absorbing flavonoids constitutes an effective non-enzymatic mechanism to mitigate 18 photoinhibitory and photooxidative damage caused by UV stress, either reducing the 19 penetration of incident UV radiation or acting as quenchers of reactive oxygen species (ROS).20 In this study, we designed a UV-exclusion experiment to investigate the effects of UV 21 radiation in Silene littorea. We spectrophotometrically quantified concentrations of both 22 anthocyanins and non-anthocyanin flavonoids (flavones) in petals, calyces, leaves and stems.23 Furthermore, we analyzed the UV effect on the photosynthetic activity in hours of maximum24 solar radiation and we tested the impact of UV radiation on male and female reproductive 25 performance. We found that anthocyanin concentrations showed a significant decrease of 26 about 20% with UV-exclusion in petals and stems, and 30% in calyces. Flavone 27 concentrations showed a significant reduction of approximately 25% in calyces and stems, 28 and 12% in leaves. Photochemical efficiency of plants grown under UV stress decreased 29 sharply at maximum light stress, but their ability for recovery after light-stress was not 30 affected. In addition, exposure to UV radiation does not seem to affect ovule production or 31 seed set, but decreases the total seed production per plant and pollen production by 69% 32 and 31%, respectively. Our results demonstrate that UV radiation produced opposite effects 33 on flavonoid accumulation and reproduction in S. littorea. UV stress increased flavonoid 34 concentrations, suggesting a photoprotective role of flavonoids against UV radiation, but 3 35 had negative consequences for reproduction. We propose that this trade-off helps this 36 species to occupy exposed habitats with high UV radiation. 37 38 Keywords: abiotic stress, anthocyanins, Caryophyllaceae, flavones, male and female 39 reproductive performance, photoprotection, photosynthesis, secondary metabolites, UV 40 radiation. 4 41 Introduction 42 Ultraviolet (UV) radiation can both help and harm plants. Many flowering plants rely 43 on UV nectar guides for pollination services [1]. Simultaneously, the high energy of UV 44 radiation can be damaging to cells and presents a unique abiotic challenge to most land 45 plants [2]. Furthermore, the "invisible" nature of UV radiation makes it particularly enigmatic 46 at the ecological and physiological scales. UV-A (315 -400 nm) and UV-B (280 -315 nm)47 radiation has numerous positive and negative effects at the cellular and organismal scales 48 [3-6], inducing a variety of morphological responses in plants [4,7]. In addition, UV-B49 radiation exerts damaging effects on DNA and chloroplasts, particularly photosystem II (PSII), 50 and indirectly generate reactive oxygen species (ROS) that can further damage the 51 photosynthetic apparatus [8,9]. 52Plants have developed a variety of mech...

Maternal flower color, ultraviolet protection, and germination in Ipomopsis aggregata (Polemoniaceae)

“…More commonly, studies are experimental tests of UV exposure on maternal fitness and seed quality. In a study in the Mediterranean plant, Silene litorrea, UV exposure promoted the accumulation of phenolics at the expense of reproduction (Del Valle et al, 2020). These authors noted a reduction in seed number and seed set but did not examine germination or post-germination effects.…”

Integrated metabolomic and transcriptomic analyses reveal different metabolite biosynthesis profiles of Juglans mandshurica in shade

“…Secondary metabolites play a key role in the plant response to environmental changes; however, there are few reports on biosynthesis plasticity of secondary metabolites (Del Valle et al, 2018). In particular, among many secondary metabolites of plants, flavonoids are very important.…”