Photoprotective response to chilling differs among high and low latitude Larrea divaricata grown in a common garden

Abstract

Cold temperatures can cause imbalances between light absorption and photosynthetic light utilization, with potential negative consequences for leaf function. Consequently, in response to chilling evergreens typically exhibit increased total pools of photoprotective xanthophyll cycle pigments and greater nocturnal retention of energy dissipating forms. This may preclude opportunistic responses to transient warmer temperatures, however, and become less beneficial as cold spells become rare and/or short-lived, for example, at the low latitude edges of warm deserts. Thus, we hypothesized intrinsic differences in the photoprotective response to chilling between low and high latitude populations of the widespread warm desert evergreen shrub Larrea divaricata. We determined leaf pigment compositions for high and low latitude plants grown in a common garden before and after 7 days of chilling (12/1 °C day/night). High and low latitude plants differed in pigment composition before chilling, and plants from both populations adjusted pigment compositions in response to chilling. Chilling, however, induced significantly greater nocturnal retention of xanthophyll cycle pigments as zeaxanthin and antheraxanthin in high latitude plants compared to those from low latitude. These data provide strong evidence for intrinsic differences between high and low latitude populations in their photoprotective responses to both the greenhouse growth environment and to chilling.