Abstract
Chloroplast relocations are induced in response to light conditions. Chloroplasts move toward weak light (accumulation response) and avoid from strong light (avoidance response). The responses have been reported to be essential for plant survival. To date, we have screened Arabidopsis mutants and have identified several genes involved in chloroplast relocations. In this study, we isolated 2 novel mutants, web1 and web2, defective of avoidance response. Velocity of chloroplast avoidance movement in web1 and web2 were slower than that in wild-type. Both corresponding genes encode coiled-coil proteins, and their expression patterns were closely similar. Interaction between WEB1 and WEB2 were found by the yeast two-hybrid analysis. GFP-fused WEB1 localized to cell periphery and slightly in cytosol. GFP-fused WEB2 localized only in cytosol. Bimolecular fluorescence complementation analysis revealed their interaction in cytosol. These results suggest that cytosolic WEB1-WEB2 complex modulates velocity of chloroplast avoidance movement in Arabidopsis.