Sensitivity of Chloroplast Movements Along an Elevational Gradient Among Three Alpine Plant Species With Different...

Chloroplast movements are an important photoprotective mechanism in land plants. The magnitude of chloroplast responses depends on light conditions. We investigated variation in chloroplast movements and leaf physiological traits in three species: a deciduous dwarf shrub, Vaccinium myrtillus, and two wintergreen herbaceous perennials, Homogyne alpina and Soldanella carpatica, growing along gradients of elevation and light in the Tatra Mountains. In leaves of V. myrtillus, the highest amplitude of chloroplast avoidance was found at the highest-elevation alpine site. The maximum photosynthetic yield of photosystem II (F_v/F_m) in this species was robust to changes in elevation but varied with the local light environment alongside chloroplast movements. In the herbaceous species, both the magnitude of chloroplast avoidance and F_v/F_m decreased with elevation. In all three species, plants growing in the forest understorey exhibited three to four times higher changes in leaf transmittance due to chloroplast movements than plants from nearby unshaded sites, indicating acclimation to low light. In all three species studied, the magnitude of transmittance changes accompanying chloroplast avoidance was positively correlated with the specific leaf area. The differences among species in the effects of elevation on chloroplast movements suggest that the sensitivity of this response may differ across plant life forms and leaf lifespan.