Expression of genes for cell-wall proteins in dividing and wounded tissues ofZea mays L.

Hydroxyproline-rich glycoproteins (HRGPs) fromZea mays have been immunolocalized in the cell wall of root tip cells using ultrathin sections and antibodies ellicited against the purified protein. The accumulation of mRNA corresponding to this protein was studied using the cDNA probe. Maximum accumulation of the mRNA was found in tissues with a high proportion of dividing cells such as those in the root tip of young maize seedlings and a close relationship with cellular division was also observed in in-vitro cultures. However, the level of the mRNA in elongating tissues was minimal, as shown by studies carried out on the elongation zones of root tips and coleoptiles. The mRNA was induced by stress conditions, particularly by wounding young leaves and coleoptiles. It is concluded that in maize this group of proline-rich cell-wall proteins accumulates during cell division and not during cell elongation or differentiation, and participates in the stress-response mechanisms of the plant.The authors are grateful to Drs. J.A. Martinez-Izquierdo and M. Pages (Dep. Genetica Molecular, CID-CSIC, Barcelona, Spain) for critical revision of the manuscript and Plan Nacional and the European Communities for continuous financial support. This work was partially supported by the Comissio Interdepartemental de Recerca i Innovacio Tecnologica. L.R.-A. and M.P.V. are recipients of the Plan de Formacidn de Personal Investigador (Biotechnology) fellowships.Peer reviewe