INTERGENERIC TRANSFER OF A PARTIAL GENOME AND DIRECT PRODUCTION OF MONOSOMIC ADDITION PLANTS BY MICROPROTOPLAST FUSION

Results are reported on the transfer of single, specific chromosomes c arrying kanamycin resistance (Kan(R)) and beta-glucuronidase (GUS) tra its from a transformed donor line of potato (Solanum tuberosum) to a r ecipient line of the tomato species Lycopersicon peruvianum through mi croprotoplast fusion. Polyethylene glycol-induced mass fusion between donor potato microprotoplasts containing one or a few chromosomes and normal recipient diploid L, peruvianum protoplasts gave several Kan(R) calli. A high frequency of plants regenerated from Kan(R) calli expre ssed both Kan(R) and GUS, and contained one or two copies of npt-II an d a single copy of gus. Genomic in situ hybridization showed that seve ral microprotoplast hybrid plants had one single potato donor chromoso me carrying npt-II and gus genes and the complete chromosome complemen t of the recipient L. peruvianum (monosomic additions). Several monoso mic-addition hybrid plants could be regenerated within the short time of 3 months and they were phenotypically normal, resembling the recipi ent line. These results suggest that the transfer of single chromosome s is tolerated better than is the transfer of the whole donor genome. The unique advantages of microprotoplast fusion are discussed: these i nclude the direct production of monosomic addition lines for the trans fer and introgression of economically important traits in sexually-inc ongruent species, the construction of chromosome-specific DNA libaries , high-resolution physical mapping and the identification of alien chr omosome domains related to gene expression.