Impact of erecta mutation on leaf serration differs between Arabidopsis accessions.

Serrations or teeth of plant leaves are a morphological trait regulated genetically and environmentally. Very recently, it has been reported that the receptor kinases encoded by three ERECTA (ER)-family genes, ER, ER-LIKE1 (ERL1) and ERL2, redundantly play a role in tooth growth in Arabidopsis thaliana. In the report, Columbia (Col) accession was used for analyses, where none of the signal mutant of the ER-family genes exhibited serration defects. The toothless, smooth leaf margin phenotype was evident only when two out of the three ER-family genes were lost. Interestingly, it has been widely recognized that the Arabidopsis accession Landsberg erecta (L.er), which carries a loss-of-function mutation in ER, develops round leaves with smaller leaf teeth. Here, we show that the functional ER transgene promotes the tooth growth in L.er to the level of Col, indicating that the er mutation in L.er is likely responsible for the reduced growth of leaf teeth. This suggests that er single mutation affects tooth growth in a different manner between Col and L.er backgrounds, though the molecular basis for this background-dependent effect remains to be addressed.