Restitution gametes in sugar beet primary trisomics

3 Pags.Restitution gametes were observed at the end of the meiotic cycle in five primary trisomic types of sugar beet (Beta vulgaris L., 2n = 18). Nuclear restitution as measured by the percentage of pollen mother cells showing triads or dyads at the sporad stage was less than 2% for four trisomic types. Dosage effects of chromosome 5 seemed to enhance 2n pollen formation. Rants trisomic for chromosome 5 showed triads and dyads at the sporad stage with a frequency ranging from 6 to 48% among plants. Conclusive evidence of sexual polyploidization was shown by the presence of 28 chromosome progeny obtained from 2x × (2x + 1) and (2x + 1) × (2x + 1) crosses. The average frequency of triploids on the offspring of Triplo 5 was 4% in plants of a homozygous trisomic series and 8% among plants of the other available series.Peer reviewe