| Tetraploid (2n=4x=48), 2EBN, Mexican wild species in the series Longipedicellata which consists of Solanum fendleri, S. hjertingii, S. papita, S. polytrichon, and S. stoloniferum were crossed with two 2EBN cultivated diploid (2n=2x=24) clones. The resulting triploid hybrids (2n=3x=36) produced 2n pollen (triplandroids) by the mechanism of parallel orientation of Anaphase II spindles. Percentage of stainable pollen in 520 triploids ranged between 0 to 23.5% with a mean of 2.7%. Triploids producing 13.0%, 15.7%, and 23.5%, 2n pollen were crossed as staminate parents to the tetraploid cultivars resulting in pentaploid (2n=5x=60) and near-pentaploid hybrids. Crosses of triploids with lower percentage of 2n pollen as pollen parent to the tetraploid cultivars did not yield fruit, unless rescue pollen from a tetraploid cultivar was added 2 days later. Pentaploid hybrids were selected among selfed tetraploid progenies using morphological and isozyme markers transmitted from their cultivated diploid parents. These pentaploid hybrids were vigorous and had uniformly sterile pollen. However, they were female fertile and were crossed with tetraploid cultivars yielding an average of 19 seeds per fruit. Triplandroids provide the opportunity of transferring 2EBN tetraploid Mexican wild species in the series Longipedicellata germplasm into the 4EBN cultivated potatoes.; The wild species were analyzed for isozyme banding patterns which differed from the cultivated tetraploid potato. Solanum fendleri, S. hjertingii, S. papita, and S. polytrichon had unique bands for enzymes phosphoglucoseisomerase (PGI), malate dehydrogenase (MDH), and triosephosphateisomerase (TPI). Solanum stoloniferum had unique bands for PGI, MDH, TPI and aspartate amino transferase (AAT). Isozyme bands unique to the wild species were passed to the triploid (2n=3x=36) as well as pentaploid (2n=5x=60) hybrids. Transmission of TPI, PGI and MDH markers from the wild species S. fendleri, S. papita, and S. stoloniferum to backcross 2 progeny was 44% (of 138 plants), 40% (of 119 plants), and 38% (of 132 plants) respectively. Transmission of AAT marker from S. stoloniferum to 43 BC{dollar}{bsol}sb2{dollar} plants was 63%. These results reflect differential gene introgression from the wild species genomes. |
