It is well known that haploids extracted from Solanum tuberosum ssp. tuberosum provide unique opportunities for germplasm transfer and genetic manipulation.
Haploid extraction in potato has become a routine method since Hougas & Peloquin (1957) showed that haploids are relatively easy to obtain from 4x x 2x crosses.
Haploids can be easily hybridized with most 24-chromosome tuber bearing species. The hybrids obtained are vigorous, fertile and have an improved tuberization under long-day conditions. Hermundstad (1984) found that many of the haploid tuberosum-species hybrids outyielded their haploid parents as well as some 4x cultivars.
Results on the extraction of haploids from varieties adapted to Italian conditions are reported in this paper.
MATERIALS AND METHODS
Four varieties widely grown in Italy (Desiree, Jaerla, Primura and Sirtema) were crossed with pollinator S. phureja, clone PI 1.22. All crosses were done using the technique described by Peloquin & Hougas (1958). Seedlings from the crosses were grown in the glasshouse and root-tip chromosomes were counted.
RESULTS AND DISCUSSION
The results of the pollination, in terms of fruit set, seeds, seedlings, haploid frequency and haploids per 100 fruits are presented in Table 1.
A total of 863 pollinations were made which resulted in 286 fruits, 329 seeds and 250 seedlings. More than 14% of the seedlings were found to be haploids with an average of 12.1 haploids per 100 fruit.
The ability of the clone PI 1.22 to induce haploids with the four parents used was confirmed.