Improper excess light energy dissipation in Arabidopsis results in a metabolic reprogramming.
BACKGROUND
Plant performance is affected by the level of expression of PsbS, a key photoprotective protein involved in the process of feedback de-excitation (FDE), or the qE component of non-photochemical quenching, NPQ.


RESULTS
In studies presented here, under constant laboratory conditions the metabolite profiles of leaves of wild-type Arabidopsis thaliana and plants lacking or overexpressing PsbS were very similar, but under natural conditions their differences in levels of PsbS expression were associated with major changes in metabolite profiles. Some carbohydrates and amino acids differed ten-fold in abundance between PsbS-lacking mutants and over-expressers, with wild-type plants having intermediate amounts, showing that a metabolic shift had occurred. The transcriptomes of the genotypes also varied under field conditions, and the genes induced in plants lacking PsbS were similar to those reportedly induced in plants exposed to ozone stress or treated with methyl jasmonate (MeJA). Genes involved in the biosynthesis of JA were up-regulated, and enzymes involved in this pathway accumulated. JA levels in the undamaged leaves of field-grown plants did not differ between wild-type and PsbS-lacking mutants, but they were higher in the mutants when they were exposed to herbivory.


CONCLUSIONS
These findings suggest that lack of FDE results in increased photooxidative stress in the chloroplasts of Arabidopsis plants grown in the field, which elicits a response at the transcriptome level, causing a redirection of metabolism from growth towards defence that resembles a MeJA/JA response.
Frenkel
Martin
M
Department of Plant Physiology, Umeå University, Umeå Plant Science Centre, Umeå, Sweden. martin.frenkel@emg.umu.se
Külheim
Carsten
C
Jänkänpää
Hanna Johansson
HJ
Skogström
Oskar
O
Dall'Osto
Luca
L
Agren
Jon
J
Bassi
Roberto
R
Moritz
Thomas
T
Moen
Jon
J
Jansson
Stefan
S
D000085:Acetates / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002736:Chloroplasts / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D008027:Light; D045342:Light-Harvesting Protein Complexes; D020411:Oligonucleotide Array Sequence Analysis; D054883:Oxylipins / Q000378:metabolism / Q000494:pharmacology; D010126:Ozone / Q000494:pharmacology; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological
D000085:Acetates; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D045342:Light-Harvesting Protein Complexes; C489731:NPQ4 protein, Arabidopsis; D054883:Oxylipins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010126:Ozone; C011006:jasmonic acid; C072239:methyl jasmonate