Genome uncoupled (gun) phenotype is associated with root growth repression in Arabidopsis seedlings grown on lincomycin

«Genome uncoupled» (gun) is a molecular phenotype manifesting in a high expression of a number of nuclear photosynthesis associated genes in plants with arrested chloroplast biogenesis. The chloroplast biogenesis arrest could be achieved by growing of plants in presence of lincomycin (plastid translation inhibitor) or norflurazon (carotenoid biosynthesis inhibitor). We have found that Arabidopsis thaliana gun1-1gun5-1 double mutant seedlings with gun phenotype associated with both lincomycin and norflurazon demonstrate a repressed root growth when germinated on lincomycin but not norflurazon-containing media. Statistical analysis has demonstrated a high negative correlation between root length and gun phenotype evaluated on both LHCB1.2 and HEMA1 genes expression in three gun mutants of Arabidopsis: gun1-1, cch1-1 and the double mutant gun1-1gun5-1. Our results demonstrate that regulatory signals of plastid origin might participate in root development.