seurat dotplot lengend text ptsize

FeaturePlot(object = obj, "gene", split.by = "orig.ident") &
  scale_colour_gradientn(colours =rev(brewer.pal(n = 10, name = "RdBu"))) & 
  theme(text = element_text(face = "bold"),
        axis.text.x=element_text(angle=45, hjust=1, size=30),
        axis.title = element_text(size=30,face="bold"),
        axis.title.y.right = element_text(size = SIZE HERE),
        legend.text=element_text(size=50),
        legend.title=element_text(size=50),
        axis.line = element_line(size=2))