Abstract
Lateral root (LR) formation is important for the establishment of root architecture in higher plants. To understand the molecular mechanism of LR formation, we isolated the novel recessive mutant rlr50 (reduced lateral root formation 50) in Arabidopsis thaliana. This mutant shows the decreased LR primordium density (about 60% of the wild-type density). Exogenous auxins promoted LR formation and inhibited primary root growth in rlr50, suggesting the mutation does not directly affect the auxin responsibility in roots. Map-based cloning revealed that RLR50 gene encodes a novel unknown protein. Expression analysis indicated that RLR50 is expressed in almost all organs of the plant. In addition, functional GFP-tagged RLR50 proteins are localized in the cytosol both in cultured cells and in planta, suggesting that RLR50 functions in the cytosol. Taken together, we conclude that RLR50 is a novel factor that controls LR primordium formation.
