Drought affects the heat-hardening capacity of alpine plants as indicated by changes in xanthophyll cycle pigments, singlet oxygen scavenging, α-tocopherol and plant hormones

• DOI: 10.1016/j.envexpbot.2016.10.010
• Publication Date: 2016-10-18T15:45:09Z
• Authors: Othmar Buchner; Thomas Roach; Joy Gertzen; Stephanie Schenk; Matthias Karadar; Wolfgang Stöggl; Ramona Miller; Clara Bertel; Gilbert Neuner; Ilse Kranner
• Keywords: Hardening (computing); Plant Physiology

Alpine environments in Europe are increasingly affected by more erratic precipitation patterns, and frequent drought heat waves. Heat-hardening capacity is a key feature for survival of these abiotic stress factors, but it poorly understood how affect plant performance when combined. The main objectives this study were (1) to determine maximum hardening 14 selected species (2) alpine plants respond combined compared alone. (3) For risk assessment leaf temperatures measured the field (4) important methodological aspects testing tolerance evaluated. Heat was assessed Tc, threshold photosystem II (PS II), tests based on visual inspection tissue damage or potential quantum efficiency PS (Fv/Fm). A purpose-built Tolerance Testing System (HTTS) used, which allows controlled exposure whole under nearly natural conditions. Additionally, two from contrasting habitats, Senecio incanus Primula minima, dynamics studied during after 8 days (H), combination severe (H+D) within light-transmissive chamber at site. In both species, H treatment significantly increased (LT50), determined HTTS, 58.0 °C 54.9 °C, respectively, accompanied elevated production abscisic acid (ABA) salicylic (SA), whereas jasmonic (JA) levels decreased. Under H+D LT50 only 56.5 51.6 ABA higher S. SA lower comparison H. Changes xanthophyll cycle pigments, α-tocopherol carotenoids:chlorophyll ratio pronounced P. minima than incanus. singlet oxygen (1O2) scavenging capacity, electron paramagnetic resonance spectroscopy (EPR). field, half-hourly mean (HHM) temperature (32.2 °C) (46.5 potentially harmful temperature). We conclude that investigated well adapted prevailing conditions field. They also possess an outstanding can be curtailed with drought. As further increases temperatures, suffering lethal some may increase future, particularly south exposed, ruderal sites uncertain water supply.