RCD1 and SRO1 are necessary to maintain meristematic fate in Arabidopsis thaliana

The RADICAL-INDUCED CELL DEATH1 and SIMILAR TO RCD ONE1 genes of Arabidopsis thaliana encode members of the poly(ADP-ribose) polymerase (PARP) superfamily and have pleiotropic functions in development and abiotic stress response. In order to begin to understand the developmental and molecular bases of the defects seen in rcd1-3; sro1-1 plants, this study used the root as a model. Double mutant roots are short and display abnormally organized root apical meristems. However, acquisition of most cell fates within the root is not significantly disrupted. The identity of the quiescent centre is compromised, the zone of cell division is smaller than in wild-type roots and abnormal divisions are common, suggesting that RCD1 and SRO1 are necessary to maintain cells in a division-competent state and to regulate division plane placement. In addition, differentiation of several cell types is disrupted in rcd1-3; sro1-1 roots and shoots, demonstrating that RCD1 and SRO1 are also necessary for proper cell differentiation. Based on the data shown in this article and previous work, we hypothesize that RCD1 and SRO1 are involved in redox control and, in their absence, an altered redox balance leads to abnormal development.