Abstract
Interspecific hybrids between Lactuca saligna and L. sativa cv. Bronze were obtained only when L. saligna was used as a seed parent. The seed set ratio of the Fj hybrid was very low (12.0%), however, their seed germination rate was 87.5%. In pollen mother cells of the Ft hybrids, univalent chromosomes were observed at metaphase I and the number of chiasma at diakinesis was fewer than their parental species. At pollen tetrad stage, the number of microspores of FI hybrids varied between 2 and 6. In some F2 hybrids, distorted staining intensities showed a 4:4:1 ratio in all or some of the 5 isozyme loci, suggesting that they were triploids or aneuploids, respectively. The triploids in F2 progeny were screened by flow cytometric analysis at the 2- week-old seedling stage. Microscopic observation of chromosome revealed that 14 of 103 F2 plants were found to be triploid, 2n=3x=27; no aneuploid plants were observed indicating that aneuploids do not survive until the 3- to 4-week-old seedling stage.
