MULTIPLE ANEUPLOIDS FROM INTERSPECIFIC CROSSES IN SOLANUM: FERTILITY AND CYTOLOGY

Abstract

Approximately 30% of the progeny from interspecific 3x-2x crosses were multiple aneuploids (2n = 26-29). Seven interspecific multiple aneuploids from the crosses Solanum magilia × S. berthaultii, S. maglia × S. microdontum, and (S. tuberosum × S. berthaultii) × S. berthaultii were studied to determine their chromosome complements and to assess their potential value for associating genes with particular chromosomes. These clones grew vigorously in the field but some were dwarf and compact in habit. Six of the seven clones were female fertile. At metaphase I, 0.54 to 0.72 trivalents were formed per extra chromosome. Chain and "Y" trivalents were found most frequently. The average number of chromosomes at prophase II and metaphase II was 13.31 for five triple trisomics. Pachytene analysis of six of the multiple aneuploids indicated that in five of the clones, one or two of the extra chromosomes were isochromosomes. Complete chromosomes II, III, IV, X, and XII and isochromosomes of I, III, and XI have been identified in these clones.