Climatic origins predict variation in photoprotective leaf pigments in response to drought and low temperatures in live oaks (Quercus series Virentes).
Climate is a major selective force in nature. Exploring patterns of inter- and intraspecific genetic variation in functional traits may explain how species have evolved and may continue evolving under future climate change. Photoprotective pigments play an important role in short-term responses to climate stress in plants but knowledge of their long-term role in adaptive processes is lacking. In this study, our goal was to determine how photoprotective mechanisms, morphological traits and their plasticity have evolved in live oaks (Quercus series Virentes) in response to different climatic conditions. For this purpose, seedlings originating from 11 populations from four live oak species (Quercus virginiana, Q. geminata, Q. fusiformis and Q. oleoides) were grown under contrasting common environmental conditions of temperature (tropical vs temperate) and water availability (droughted vs well-watered). Xanthophyll cycle pigments, anthocyanin accumulation, chlorophyll fluorescence parameters and leaf anatomical traits were measured. Seedlings originating from more mesic source populations of Q. oleoides and Q. fusiformis increased the xanthophyll de-epoxidation state under water-limiting conditions and showed higher phenotypic plasticity for this trait, suggesting adaptation to local climate. Likewise, seedlings originating from warmer climates had higher anthocyanin concentration in leaves under cold winter conditions but not higher de-epoxidation state. Overall, our findings suggest that (i) climate has been a key factor in shaping species and population differences in stress tolerance for live oaks, (ii) anthocyanins are used under cold stress in species with limited freezing tolerance and (iii) xanthophyll cycle pigments are used when photoprotection under drought conditions is needed.
Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, MN 55108, USA josealberto.ramirezvaliente@gmail.com cavender@umn.edu.
Jose A
JA
Ramírez-Valiente
Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, MN 55108, USA Present address: Two Twelve Medical Center-Ridgeview Laboratory 111 Hundertmark Road, Chaska, MN 55318, USA.
Kari
K
Koehler
Department of Ecology, Evolution and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, MN 55108, USA josealberto.ramirezvaliente@gmail.com cavender@umn.edu.
Jeannine
J
Cavender-Bares
D000222:Adaptation, Physiological; D000872:Anthocyanins / Q000378:metabolism; D002489:Central America; D002734:Chlorophyll / Q000378:metabolism; D057231:Climate Change; D003080:Cold Temperature; D055864:Droughts; D014644:Genetic Variation; D009656:North America; D010860:Pigments, Biological / Q000378:metabolism*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology*; D029963:Quercus / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D013045:Species Specificity; D024341:Xanthophylls / Q000378:metabolism
D000872:Anthocyanins; D010860:Pigments, Biological; D024341:Xanthophylls; D002734:Chlorophyll
anthocyanins; climatic gradient; clinal variation; cold response; drought response; physiological adaptation; red leaves; xanthophyll cycle