There is no better use of sexual reproduction in regard to breeding and genetic research than the ploidy level manipulations possible in the potato and its relatives. Unique reproductive characteristics of tuber-bearing Solanum species make possible: the production of gametes with unreduced chromosome number; the presence of an endosperm dosage system that regulates success of interploidy/interspecific crosses; the possibility to easily extract maternal haploids following crosses with S. phureja. This paper reviews results obtained in scaling genomic multiples up and down in potato, and relates these manipulations to breeding strategies for the genetic improvement of the cultivated potato. Several ploidy series have been developed, ranging from the monoploid to the hexaploid level. Cultivated tetraploids were scaled down to the diploid and monoploid level by haploidy. Scaling upward was achieved by sexual polyploidisation via 2n gametes that resulted in triploid, tetraploid, pentaploid, and hexaploid genotypes with a broad genetic base. Altogether, the success of ploidy level manipulations constitutes further proof that sexual polyploidisation played an important role in the polyploid evolution of Solanum species, and supports the idea that gene flow can be relatively easily accomplished through interploid and bridge crosses.
ReferencesAdiwilaga K D, Brown C R. 1991. Use of 2n pollen-producing triploid hybrids to introduce tetraploid Mexican wild species germ plasm to cultivated tetraploid potato gene pool. Theoretical and Applied Genetics 81:645-652. Andrivon D, Corbière R, Lucas J M, Pasco C, Gravoueille J-M, Pellé R, Dantec J-P, Ellissèche D. 2003. Resistance to late blight and soft rot in six potato progenies and glycoalkaloid contents in the tubers. American Journal of Potato Research 80:125-134. Bamberg J B, Hanneman Jr R E, Palta J P, Harbage J F. 1994. Using disomic 4x (2EBN) potato species germplasm via bridge Solanum commersonii. Genome 37:866-870. Barone A, Sebastiano A, Carputo D, della Rocca F, Frusciante L. 2001. Molecular marker-assisted introgression of the wild Solanum commersonii genome into the cultivated S. tuberosum gene pool. Theoretical and Applied Genetics 102:900-907. Breukelen E W M van, Ramanna M S, Hermsen Th J G. 1975. Monohaploids (2n=x=12) from autotetraploid Solanum tuberosum (2n=4x=48) through two successive cycles of female parthenogenesis. Euphytica 24:567-574. Breukelen E W M van, Ramanna M S, Hermsen J G Th. 1977. Parthenogenetic monohaploids (2n=x=12) from Solanum tuberosum L. and S. verrucosum Sclechtd and the production of homozygous potato diploids. Euphytica 26:263-271. Brown C R. 1988. Characteristics of 2n pollen producing triploid hybrids between Solanum stoloniferum and cultivated diploid potatoes. American Potato Journal 65:75-84. Brown C R, Adiwilaga K. 1990. Introgression of Solanum acaule germ plasm from the endosperm balance number 2 gene pool into the cultivated endosperm balance number 4 potato gene pool via triplandroids. Genome 33:273-278. Buso J A, Reifschne...