Somatic hybridization can transfer:
Somatic hybridization can transfer extensive genetic material ranging from blocks of linked genes to entire chromosomes or whole genomes, contrasting with single gene transformation using plasmid vectors. When two protoplasts fuse, initial heterokaryon contains cytoplasm of both parents and nuclei that may fuse producing allotetraploid somatic hybrid carrying full complement of chromosomes from both species, allowing introgression of polygenic quantitative trait loci QTL controlled by multiple genes interacting for disease resistance, abiotic stress tolerance, quality attributes that cannot be transferred via single gene approach. Through asymmetric fusion where donor protoplasts irradiated with gamma rays fragment chromosomes before fusion, partial genome transfer achieved moving chromosome segments or single added chromosomes into recipient background, verifiable by genomic in situ hybridization GISH. This permits wide hybridization circumventing sexual incompatibility barriers pre zygotic and post zygotic including endosperm abortion. Iconic examples include transfer of late blight resistance gene cluster from wild Solanum brevidens to cultivated potato conferring durable resistance dependent on multiple R genes clustered in genomic block, demonstrating somatic hybridization power for moving complex agronomic traits impossible by conventional crossing.
Ref: Helgeson 1979 potato somatic hybrid; Bhat & Bhat 2011 gene blocks transfer.