Expression in Tobacco of a Functional Monoclonal Antibody Specific to Stylet Secretions of the Root-Knot Nematode. T. J Baum. Department of Plant Pathology, University of Georgia, Athens, GA 30602. A. Hiatt (4), W. A. Parrott (2), L. H. Pratt (3), and R. S. Hussey (1). (1) Department of Plant Pathology, (2) Department of Crops and Soil Sciences, and (3) Department of Botany, University of Georgia, Athens, GA 30602 U.S.A; (4) Plant Biotechnology, 8445 Camino Santa Fe, Suite 102, San Diego, CA 92121 U.S.A. MPMI 9:382-387. Accepted 20 February 1996. Copyright 1996 The American Phytopathological Society.

Genes for the heavy and light protein chains of a monoclonal antibody (6D₄) specific to stylet secretions of Meloi-dogyne incognita were cloned as cDNAs containing a native leader sequence. Heavy and light chain constructs under control of the cauliflower mosaic virus 35S promoter were transformed independently into Xanthi tobacco. Transgenic plants producing either heavy or light chain protein were crossed, yielding progeny that produced assembled and functional 6D₄ immunoglobulins (plantibodies). Specificity of plantibodies was identical to 6D₄ derived from the hybridoma cell line, i.e., both bound to the root-knot nematode esophageal glands and stylet secretions. Based on tissue print analysis, plantibodies were expressed in leaves, stems, roots, and galls. However, plantibody expression had no influence on root-knot nematode parasitism of transgenic plants. Plantibodies possibly accumulate apoplastically whereas nematode stylet secretions might be injected into the cytoplasm of the parasitized cell, precluding plantibody interference with secretion function in parasitism