STABLE TRANSFORMATION OF TOMATO CELL-CULTURES AFTER BOMBARDMENT WITH PLASMID AND YAC DNA

Stable transformants were obtained after microprojectile particle bombardment of tomato cell suspensions (Lycopersicon esculentum cv VFNT Cherry and L. pennellii). The suspensions were bombarded with tungsten particles coated with either plasmid (similar to 6.3 kb) or yeast artificial chromosome (YAC) (80 kb) DNA containing the beta-glucuronidase (GUS) and neomycin phosphotransferase II (nptII) genes. The YAC DNA contained an insert of approximately 50 kb of DNA from VFNT Cherry. L. pennellii suspensions were more amenable to transformation than VFNT Cherry; more kanamycin-resistant calli were recovered from L. pennelli after bombardment with plasmid DNA, and only L. pennellii cells produced transformants after bombardment with YAC DNA. DNA gel blot analysis confirmed the presence of the nptII and GUS genes. This analysis also confirmed the integration of YAC DNA into the genome of the kanamycin-resistant calli and suggested that the level of intactness of the integrated YAC DNA was fairly high in four of the five transformants examined. Microprojectile bombardment of regenerable cultures with YACs may ultimately aid in map-based cloning of agriculturally-important genes.