Vigorous growth of fusion products allows highly efficient selection of interspecific potato somatic hybrids: molecular proofs

Abstract

An early identification of fusion products was based on the presumed vigorous growth of hybrid calluses after fusion between Solanum brevidens and S. tuberosum leaf protoplasts. The S. brevidens protoplasts were unable to form multicellular colonies under the applied culture conditions. Three size groups of calluses were separated and analyzed at two different early phases of culture period. "Squash blot" hybridization with a S. brevidens specific repetitive DNA probe showed that the group of the largest calluses consisted of putative somatic hybrids with a frequency of 80-100% in three independent experiments. Furthermore, approximately 80-95% of the middle sized calluses and 33-90% of the smallest ones were shown to be hybrid. The unexpectedly high percentage of fusion products, even in the case of the smallest calluses, may result from the suppression of the development of parental potato colonies in cultures with mixed cell population. Till this time 120 independent colonies selected as putative hybrids have been regenerated into plants. All of them exhibited hybrid phenotype, and their hybrid origin was proved by cytological and restriction fragment length polymorphism analyses.

Identification of somatic hybrids of dihaploid Solanum tuberosum lines and S. brevidens by species specific RAPD patterns and assessment of disease resistance of the hybrids

“…The high vigour of somatic hybrids of S. brevidens and S. tuberosum was also observed by Polgar et al (1993). Final verification of nuclear hybridity was obtained through RAPD analysis, which proved to be a quick and reliable method for analyzing somatic hybrids, as previously shown by Baird et al (1992) and Xu et al (1993).…”

Cell lines and plants obtained after protoplast fusions of Rosa+Rosa, Rosa+Prunus and Rosa+Rubus

“…The onset of cell division in heterofused protoplasts was delayed by the pre-treatments with IOA and R6G. Their disturbed metabolism may have concealed an innate tendency for more rapid proliferation of cell lines with hybrid nuclear genomes, as in somatic hybrids of potato where rapid callus growth was attributed to hybrid vigour (Polgár et al, 1993). The possibility that selection could be based on hybrid vigour could be tested in fusion experiments with untreated protoplasts.…”

“…Hybrid vigour, leading to faster growth of callus from heterofused than homofused and unfused protoplasts, has been used to select somatic hybrids of potato (Polgár et al, 1993). However, strategies involving complementation between differently disabled parental protoplasts have been more widely used.…”

The integration of protoplast fusion-derived material into a potato breeding programme — a review of progress and problems

“…All these approaches rely on the use of relatively large amounts of plant material, however . The possibility of early selection of hybrids of certain combinations based on the more vigorous growth of hybrid colonies (Debnath & Wenzel, 1987) has been substantiated by molecular evidence (Polgar et al ., 1993) . Recently, the use of PCR-based methodologies such as RAPD markers, has enabled identification of fusion products at a much earlier stage (Baird et al ., 1992 ;Xu et al ., 1993) .…”