RFC3 regulates cell proliferation and pathogen resistance in Arabidopsis.

Replication factor C subunit 3 (RFC3) is one of the small subunits of the RFC complex originally purified from the HeLa cells that is essential for the in vitro replication of Simian virus 40 (SV40). Although RFC has been reported to be involved in DNA replication, DNA repair and check-point control of cell cycle progression in yeast, little is known about the precise function of each subunit of the RFC in plants. We recently reported the identification of , which carries a point mutation leading to plants with enhanced expression of () genes and resistance against the virulent oomycete () Noco2. The mutant is hypersensitive to SA and has enhanced pathogen resistance independent of Nonexpressor of genes 1 (NPR1). The mutation caused a substitution from a nonpolar aliphatic amino acid (Gly-84) to a negatively charged amino acid (Asp) in functional domain III, which is one of eight conserved domains in the RFC. This may interfere with the interaction between RFC3 and other subunits, compromising the function of the protein complex, and leading to cell proliferation defects in the leaves and roots of Arabidopsis. Furthermore, enhanced expression of genes and induction of systemic acquired resistance in may be caused by a partial loss of RFC function through its involvement in replication-coupled chromatin assembling.