Journal Article

Physcomitrella patens mutants affected on heat dissipation clarify the evolution of photoprotection mechanisms upon land colonization

Giacometti, Giorgio M., Alboresi, Alessandro, Morosinotto, Tomas, von Wettstein, Diter, Bassi, Roberto, Gerotto, Caterina

2010

Overview

Light is the source of energy for photosynthetic organisms; when in excess, however, it also drives the formation of reactive oxygen species and, consequently, photoinhibition. Plants and algae have evolved mechanisms to regulate light harvesting efficiency in response to variable light intensity so as to avoid oxidative damage. Nonphotochemical quenching (NPQ) consists of the rapid dissipation of excess excitation energy as heat. Although widespread among oxygenic photosynthetic organisms, NPQ shows important differences in its machinery. In land plants, such as Arabidopsis thaliana, NPQ depends on the presence of PSBS, whereas in the green alga Chlamydomonas reinhardtii it requires a different protein called LHCSR. In this work, we show that both proteins are present in the moss Physcomitrella patens. By generating KO mutants lacking PSBS and/or LHCSR, we also demonstrate that both gene products are active in NPQ. Plants lacking both proteins are more susceptible to high light stress than WT, implying that they are active in photoprotection. These results suggest that NPQ is a fundamental mechanism for survival in excess light and that upon land colonization, photosynthetic organisms evolved a unique mechanism for excess energy dissipation before losing the ancestral one found in algae.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Algae / Antennas / Aquatic plants / Arabidopsis - genetics / Arabidopsis - metabolism / Arabidopsis thaliana / autotrophs / Base Sequence / Biological Evolution / Biological Sciences / Bryopsida - genetics / Bryopsida - metabolism / Chlamydomonas reinhardtii / Chlamydomonas reinhardtii - genetics / Chlamydomonas reinhardtii - metabolism / Colonization / DNA Primers - genetics / embryophytes / energy / Energy dissipation / Evolution & development / Fluorescence / Gene Knockout Techniques / genes / Genes, Plant / Genomes / heat / Hot Temperature / Light / Light intensity / Mosses / mosses and liverworts / mutants / Mutation / Phenotypes / photoinhibition / photostability / Photosynthesis / Photosynthesis - genetics / Photosynthesis - physiology / Photosynthetic Reaction Center Complex Proteins - genetics / Photosynthetic Reaction Center Complex Proteins - metabolism / Physcomitrella patens / Plant biology / Plant Proteins - genetics / Plant Proteins - metabolism / Plants / Proteins / reactive oxygen species / Species Specificity / Stress, Physiological / Thylakoids / Vascular plants / Western blotting