Molecular marker analysis of 24- and 25-chromosome plants obtained from Solanum tuberosum L. subsp. andigena (2n = 4x = 48) pollinated with a Solanum phureja haploid inducer.

Clones with 24 or 25 chromosomes were obtained by pollinating an Andean cultivated tetraploid potato (Solanum tuberosum subsp. andigena clone 94H94, 2n = 4x = 48) with the Solanum phureja haploid-inducer clone 1.22. Their genetic composition was analyzed in an RAPD assay using 135 decamer primers and in an RFLP assay using 45 single-copy DNA probes. In total, 22 RAPD and 20 RFLP markers were found to be specific to S. phureja. None of these markers were found in the 24- and 25-chromosome clones. RFLP genotypes for the 45 RFLP loci were further determined for each clone. Genotypes of the 24-chromosome clones were characterized using two alleles randomly selected from four alleles of the parental tetraploid clone for almost all RFLP loci. Five 25-chromosome clones had extra alleles for all of the RFLP loci of chromosomes 4, 8, 10, 11, and 12, respectively, suggesting primary trisomy for one of these chromosomes. Clones with genotypes showing double reduction were also identified. Therefore, the obtained clones likely originated from random samples of female gametes, and hence are euhaploids or aneuhaploids of S. tuberosum subsp. andigena, strongly supporting parthenogenesis to be a primary mechanism for haploid induction in potato.