Contribution of PsbS Function and Stomatal Conductance to Foliar Temperature in Higher Plants.
Natural capacity has evolved in higher plants to absorb and harness excessive light energy. In basic models, the majority of absorbed photon energy is radiated back as fluorescence and heat. For years the proton sensor protein PsbS was considered to play a critical role in non-photochemical quenching (NPQ) of light absorbed by PSII antennae and in its dissipation as heat. However, the significance of PsbS in regulating heat emission from a whole leaf has never been verified before by direct measurement of foliar temperature under changing light intensity. To test its validity, we here investigated the foliar temperature changes on increasing and decreasing light intensity conditions (foliar temperature dynamics) using a high resolution thermal camera and a powerful adjustable light-emitting diode (LED) light source. First, we showed that light-dependent foliar temperature dynamics is correlated with Chl content in leaves of various plant species. Secondly, we compared the foliar temperature dynamics in Arabidopsis thaliana wild type, the PsbS null mutant npq4-1 and a PsbS-overexpressing transgenic line under different transpiration conditions with or without a photosynthesis inhibitor. We found no direct correlations between the NPQ level and the foliar temperature dynamics. Rather, differences in foliar temperature dynamics are primarily affected by stomatal aperture, and rapid foliar temperature increase during irradiation depends on the water status of the leaf. We conclude that PsbS is not directly involved in regulation of foliar temperature dynamics during excessive light energy episodes.
Department of Plant Genetics; Breeding and Biotechnology, Faculty of Horticulture; Biotechnology and Landscape Architecture, Warsaw University of Life Sciences, Warszawa, Poland.|Plant Physiology and Biotechnology, Nicolaus Copernicus University, Lwowska Street 1, 87-100 Torun, Poland.|These authors contributed equally to this work.
Milena
M
Kulasek
Department of Plant Genetics; Breeding and Biotechnology, Faculty of Horticulture; Biotechnology and Landscape Architecture, Warsaw University of Life Sciences, Warszawa, Poland.|These authors contributed equally to this work.
Maciej Jerzy
MJ
Bernacki
Department of Plant Genetics; Breeding and Biotechnology, Faculty of Horticulture; Biotechnology and Landscape Architecture, Warsaw University of Life Sciences, Warszawa, Poland.|These authors contributed equally to this work.|Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Toruń, Poland.
Kamil
K
Ciszak
Department of Plant Genetics; Breeding and Biotechnology, Faculty of Horticulture; Biotechnology and Landscape Architecture, Warsaw University of Life Sciences, Warszawa, Poland.|These authors contributed equally to this work.
Damian
D
Witoń
Department of Plant Genetics; Breeding and Biotechnology, Faculty of Horticulture; Biotechnology and Landscape Architecture, Warsaw University of Life Sciences, Warszawa, Poland stanislaw_karpinski@sggw.pl.
Stanisław
S
Karpiński
D004237:Diuron / Q000494:pharmacology; D008027:Light; D016014:Linear Models; D008954:Models, Biological; D009928:Organ Specificity / Q000187:drug effects / Q000528:radiation effects; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects; D010940:Plant Proteins / Q000378:metabolism*; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D018526:Plant Transpiration / Q000187:drug effects / Q000528:radiation effects; D010944:Plants / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D013696:Temperature
D010940:Plant Proteins; D004237:Diuron
Excess excitation energy dissipation; Foliar temperature dynamics; Non-photochemical quenching; Photosystem II; PsbS; Thermal imaging