Identification of primary trisomics and other aneuploids in foxtail millet

A complete set of nine primary trisomics(2n + 1)for cv. 'Yugu No. 1' of fox tail millet, Setaria italica (L,) Beauv. (2n = 2x = 18), was identified cyt ologically from progenies derived from crosses between autotriploids (tn = 3x = 27) and their diploid counterparts. Five autotriploid plants were iden tified from 2100 seedlings derived from 4x-2x crosses; the reciprocal cross es (2x-4x) failed to produce autotriploids. Autotriploids grew vigorously a nd were morphologically very similar to diploids. The primary trisomics (2n = 2x = 19) constituted approximate to 32.5% of the total progeny from the 3x-2x crosses, whereas 59.8% of the descendants a ere aneuploids with chrom osome numbers ranging from 20 (double trisomics and tetrasomics) to 37 (2n = 4x + 1; or autotetraploid with one additional chromosome). The nine prima ry trisomics identified were self-fertile; seven had characteristic morphol ogy, whereas trisomics VIII and IX resembled the disomics. The seed set for trisomic V was the lowest (20%), and trisomic Vm the highest (74%). Other aneuploids with 20 or more somatic chromosomes were either self-sterile or partially fertile with various, but low, levels of seed set. Each of the pr imary trisomics showed its unique transmission rate when self-pollinated: t risomic IX had the highest (45.8%), whereas trisomic V had the: lowest (19. 6%) transmission rate.