IN PLANTA MONITORING OF THE ACTIVITY OF 2 CONSTITUTIVE PROMOTERS, CAMV 35S AND TR2', IN DEVELOPING FEEDING CELLS INDUCED BY GLOBODERA-ROSTOCHIENSIS USING GREEN FLUORESCENT PROTEIN IN COMBINATION WITH CONFOCAL LASER-SCANNING MICROSCOPY

Under the control of either the constitutive CaMV 35S or the mannopine synthase TR2' promoter, the green fluorescent protein (GFP) from the jellyfish Aeguorea victoria was expressed in transgenic potato (Solanu m tuberosum) plants. Confocal laser scanning microscopy (CLSM) was app lied to observe GFP in plants and, subsequently, to investigate promot er activity in developing feeding cells developed during potato cyst n ematode (Globodera rostochiensis) infection. Both the CaMV 35S and the TR2' promoter were strongly upregulated in young feeding cells in les s than 4 days upon infection by G. rostochiensis, whereas the GFP leve l in the surrounding tissues remained low. Optical sectioning revealed intense green fluorescence in the dense cytoplasm of the entire syncy tial cell, including the most distal cell. Furthermore, GFP was observ ed within the digestive system of the feeding nematode, showing that p roteins with an apparent molecular weight of 32 kDa can be taken up by parasitic juveniles of G. rostochiensis. Provided CLSM is used, GFP w as shown to be a powerful tool that allows in vivo monitoring of gene expression inside young developing feeding cells. Finally, the transcr iptional regulation of the CaMV 35S and TR2' promoter in plant-nematod e interactions is discussed. (C) 1998 Academic Press.