ANEUPLOIDS FROM NATURAL AND COLCHICINE-INDUCED AUTOTETRAPLOIDS OF SOLANUM

Abstract

Haploids grown from unfertilized egg cells of autotetraploid Solanum (4x = 48) were found to be either euploid (2x = 24) or hyperploid (25 through 28 chromosomes), the proportion of hyperploids being 7.6% for S. tuberosum Group Tuberosum, 1.5% for S. tuberosum Group Andigena and 9.4% for the colchicine-induced autotetraploid S. chacoense. Female transmission of the extra chromosome in eight single trisomics varied from 10.0 to 47.1%. Pachytene analysis was carried out in one clone with 27 chromosomes and in two single trisomic clones from S. chacoense. The three extra chromosomes in the first clone were identified as chromosome 2 (nucleolar chromosome), chromosome 5 and chromosome 9 following the numbering system of Yeh and Peloquin (1965). One single trisomic appeared trisomic for chromosome 5, the other probably for chromosome 7. Association of the chromosomes at MI, AI and AII was studied in eight single, two double and one triple trisomic plants. Two plants showed desynapsis. From the meiotic studies of the synaptic trisomics it was apparent that all arc primary trisomics.