Abstract
We have isolated and analyzed mutants with altered GFP fluorescence compared to parental transgenic Arabidopsis thaliana line expressing GFP reporter gene under control of a sulfur deficiency-responsive chimeric promoter. Here we report three mutants with repressed sulfur responses and reduced chlorophyll synthesis. Transcript accumulation levels of sulfur-responsive sulfur assimilatory genes such as APS reductase (APR1), sulfate transporter (Sultr4;2) and serine acetyltransferase (Serat3;2) were lower in these mutants than those of the wild-type under sulfur deficiency. Mutations causing the phenotypes were identified using a genetic map-based strategy, which were in ferredoxin-dependent glutamate synthase (GLU1), plastid RNA polymerase sigma factor (SIG2) and Mg-chelatase I subunit (CHLI1). Although these genes were known to be important for chlorophyll synthesis, we suggest that these genes may also have important roles in sulfur assimilation or sulfur-responsive gene expressions.
