Recombination of Solanum brevidens chromosomes in the second backcross generation from a somatic hybrid with S. tuberosum

Abstract

Solanum brevidens synteny groups were examined with 47 widely-distributed RFLP markers in 17 BC2 progeny from six fertile BC1 plants. The BC1 plants were derived from a single S. brevidens + S. tuberosum somatic hybrid backcrossed with S. tuberosum (potato). Probes which were linked in potato and tomato were also found to be syntenic along each of the 12 S. brevidens chromosomes. More than half of the S. brevidens synteny groups had lost one or more S. brevidens-specific RFLPs in the BC2, suggesting that recombination had occurred. For 8 of the 12 S. brevidens RFLP synteny groups, the frequency of recombinant chromosomes exceeded that of intact parental chromosomes. Using the RFLP data, 161 RAPD markers were tentatively located throughout the S. brevidens genome. Further analyses with 39 of these 161 RAPD markers generally showed that RAPD and RFLP results were comparable, but some inconsistencies were noted with 14 of the 39 RAPD markers. The extent of marker loss and the high frequency of synteny groups which were marked by a single S. brevidens-specific RFLP marker suggest that the S. brevidens chromosomes have some pairing affinity with potato chromosomes. This interaction should facilitate the transfer of novel disease-resistance traits into potato breeding lines. One plant was recovered with the chromosome number of S. tuberosum (2n=48) that carried a single S. brevidens RFLP marker, suggesting transfer of this S. brevidens marker into the genome of S. tuberosum.

Analysis of the introgression of Solanum bulbocastanum DNA into potato breeding lines

“…For RAPD analysis, DNA was extracted from single leaves of material grown in vitro, using the microprep method described by McGrath et al (1994). A miniprep DNA extraction protocol was used when larger quantities of DNA were required for RFLP analysis (Fulton et al 1995).…”

“…Somatic hybrids between S. brevidens and S. tuberosum have provided a new source of resistance to Potato Leaf Roll Virus and Erwinia soft rots (Helgeson et al 1986;Austin et al 1988). Resistance to Potato Virus Y (PVY) can be obtained from somatic hybrids of potato and S. etuberosum (Novy and Helgeson 1994). S. commersonii and potato have been hybridized to give a new resistance to bacterial wilt disease caused by Ralstonia solanacearum (Laferriere et al 1999).…”

“…These analyses have been aided by the fact that synteny of tomato and potato RFLP markers appears to be largely conserved in S. brevidens. Thus it was possible to examine segregation of chromosomes in progeny of hybrids between S. brevidens and potato (Williams et al 1993) and to develop RAPD maps that were useful for examining recombination in backcross populations in this series (McGrath et al 1994(McGrath et al , 1996. With S. brevidens + potato, and materials derived from these hybridizations, there was a strong tendency for homologous pairing of chromosomes in meiosis.…”

Transfer of tuber soft rot and early blight resistances from Solanum brevidens into cultivated potato

“…This result suggests that another potato chromosome, in addition to chromosome 8, is in aneuploidic state (five copies). Previous RFLP marker analysis indicated that C75-5 may contain parts of chromosomes 2, 4 and 5 from S. brevidens (McGrath et al 1994(McGrath et al , 1996. However, our GISH analysis only revealed the chromosome 8 from S. brevidens.…”

“…Molecular marker analysis indicated that the BC 2 clone C75-5 may retain a complete chromosome 8 and part of chromosomes 2, 4 and 5 from S. brevidens (McGrath et al 1994(McGrath et al , 1996. We used RFLP analysis to test if chromosome 8 of S. brevidens in C75-5 has been transmitted into C75-5+297.…”