INOCULATION OF PEPPERS WITH INFECTIOUS CLONES OF A NEW GEMINIVIRUS BY A BIOLISTIC PROCEDURE

Several new viral diseases have appeared in almost all horticultural areas in Mexico. Transmission of their causal agents by whiteflies and host-range data suggest the involvement of geminiviruses in most cases. One example of a severe case is the ''rizado amarillo'' disease affecting peppers in northern Mexico (Tamaulipas State). The relationship of this disease to the tigre disease previously reported by Brown et al (7) is as yet unclear. Here we report the cloning and partial molecular characterization of the genome of a bipartite geminivirus associated with pepper rizado amarillo disease. The virus is tentatively named pepper huasteco virus (PHV). The cloned viral DNAs were infectious when inoculated by bombardment into pepper plants. The bombardment was accomplished using tungsten particles coated with DNA from both genomic components. The particles were delivered using a helium pressure-based apparatus (biolistic procedure). Replication of the viral DNA in plants was confirmed by Southern analysis and polymerase chain reaction (PCR) amplification of the coat-protein gene. Plants inoculated with either the A (plasmid pIGV22) or B (plasmid pIGV21) component alone did not develop any visible symptoms, and viral DNA was not detected by molecular hybridization. The advantages of this new inoculation procedure are discussed.