Three genes belonging to the CYP98 family: CYP98A3, CYP98A8 and CYP98A9, have been reported in Arabidopsis thaliana. Analysis of mutants and expression analysis demonstrated the involvement of CYP98A3 in the synthesis of lignin monomers. As expected the CYP98A3 down-regulated lines showed altered lignin content and composition (H lignin instead of G/S lignin). These plants also exhibited a strikingly reduced size. The reasons for the changes in plant size and inhibition of development are analysed. This analysis indicated a direct impact of meta-hydroxylated phenolic precursors on cell...