Abstract
We study leaf-variegated mutants var1 and var2 in Arabidopsis, to understand the molecular mechanism leading to leaf variegation. VAR1 and VAR2 encode the ATP-dependent metalloproteases FtsH, termed FtsH5 and FtsH2, respectively. These FtsHs form a complex in thylakoid membranes of chloroplasts and play a predominant role in the repair cycle of photodamaged Photosystem II. The Arabidopsis genome contains 12 FtsH homologous and 9 of these are targeted to chloroplasts. Loss of either FtsH2 or FtsH5 leads to leaf variegation, whereas inactivation of other chloroplastic FtsH homologous genes do not. Such gene redundancy may explain why the mutations do not cause lethality, but the precise reason of forming variegation remained unknown. To identify the positive factor that control leaf variegation, we attempted to isolate suppressor mutations in which the variegated phenotype of var2-6 was suppressed. Initial characterization of one of suppressor lines will be reported.
