A novel seven-transmembrane protein may be a receptor involved in high-light stress signalling and response in Arabidopsis

Stress response signalling pathways are understood only partially in plants. This investigation provides information on a putative membrane-localized receptor that can be added to the collection of high-light (HL) stress–response-mediating proteins. Differences in the expression of a range of antioxidant genes in wild-type Arabidopsis thaliana and a null mutant in At4g21570.1 gene were evaluated using quantitative real-time polymerase chain reaction. It has been found that At4g21570.1 has an effect on the expression of a number of HL-responsive genes encoding ascorbate peroxidase 2, early light-induced protein 1 (ELIP1), type II peroxiredoxin F and two types of glutathione-S-transferases. Due to the fact that some of these genes were reported to be influenced by abscisic acid (ABA), presented results suggest that the investigated putative seven-transmembrane protein (7TMP) may be the missing link between ABA and G-protein a-subunit in plants. However, further study is needed in order to exclude the involvement of other factors, such as hydrogen peroxide, the accumulation of which in a mutant could also contribute to these changes.