A complete set of maize individual chromosome additions to the oat genome

All 10 chromosomes of maize (Zea mays, 2n = 2x = 20) were recovered as sing le additions to the haploid complement of oat (Avena sativa 2n = 6x = 42) a mong F-1 plants generated from crosses involving three different- lines of maize to eight different lines of oat. In vitro rescue culture of more than 4,300 immature F, embryos resulted in a germination frequency of 11% with recovery of 378 F-1 plantlets (8.7%) of moderately vigorous growth. Some F- 1 plants were sectored with distinct chromosome constitutions among tillers of the same plant and also between root and shoot cells. Meiotic restituti on facilitated development of un-reduced gametes in the F-1. Self-pollinati on of these partially fertile F-1 plants resulted in disomic additions (2n = 6x + 2 = 44) for maize chromosomes 1, 2,, 4, 6, 7, and 9. Maize chromosom e 8 was recovered as a monosomic addition (2n = 6x + 1 = 43). Monosomic add itions for maize chromosomes 5 and 10 to a haploid complement of oat (n = 3 x + 1 = 22) were recovered several times among the F-2 plants. Although par tially fertile, these chromosome 5 and 10 addition plants have not yet tran smitted the added maize chromosome to F-2 offspring. We discuss the develop ment and general utility of this set of oat-maize addition lines as a novel tool for maize genomics and genetics.