PLOIDY LEVELS OF PROGENY FROM DIPLOID-TETRAPLOID CROSSES IN POTATO

The discovery of an efficient means for obtaining haploids of the potato is slowly revolutionizing, reorienting, and stimulating potato research and breeding. This report is part of a study concerned with their use. as hybrids with species, in gene transfer through diploid-tetraploid hybridization. Such hybridization has been shown to be quite easily accomplished. In this paper, the ploidy level of the progeny of 4x × 2x and 2x × 4x crosses are given. The 4x × 2x cross gave 91.9% (4x), 7.6% (3x). and 0.6% (2x) based on an examination of 344 individuals, while 676 individuals of the 2x × 4x cross were found to be 94.8% (4x), 1.9% (3x), and 3.3 %(2x). The high seed set pollinators gave 98.4% (4x) and 1.6% (3x) progeny based on 551 individuals. The fact that they produced a higher frequency of tetraploids and a lower frequency of triploids than did the other 2x pollinators suggests that the triploid frequency is not dependent on seed set and also that in crosses where seed set is above average the additional seeds are likely to be tetraploid. The high frequency of tetraploids. plus the relative ease of crossing between diploids and tetraploids makes this method of gene transfer both highly effective and quite efficient. © 1968 Springer.