Comparing mitotic and meiotic tetraploid red clover plants for seed yield

New tetraploids can be created by chromosome doubling (mitotic tetraploids), or through unreduced gametes (meiotic tetraploids). In this study, meiotic tetraploids were generated in interploidy crosses, their seed yield was compared against mitotic tetraploids with similar genetic background, and the relation between genetic diversity and seed yield was explored. A total of 15 meiotic tetraploids were obtained in 16 interploidy crosses between diploid Lemmon or Merian genotypes and tetraploid Elanus genotypes. Mitotic tetraploids were created by crossing plants from tetraploidized Lemmon or Merian populations with Elanus genotypes. Tetraploid progeny from cross-pollinations were identified with flow cytometry and SSR marker analysis. The efficiency of interploidy crosses to generate meiotic tetraploids was low (0.5% in diploid and 0.7% tetraploid mother plants) and the degree of self-pollination was high (95.0% in diploid and 94.1% in tetraploid mother plants). Using seeds from the diploid parent was more time and cost efficient because most undesired progeny was identified by flow cytometry, leaving fewer plants to be screened with SSR markers. Meiotic tetraploids yielded significantly more seeds than mitotic tetraploids with similar genetic background (15.9g vs. 10.4 g), but their genetic diversity was not higher (2.6 vs. 2.9 alleles per SSR locus). Seed yield and the average allele number per locus were not correlated among all progeny plants.