Phenotypic characterization and nuclear microsatellite analysis reveal genomic changes and rearrangements underlying androgenesis in tetraploid potatoes ( Solanum tuberosum L.)

Two (di)haploids (2n = 2x = 24) and nine tetraploids (2n = 4x = 48) obtained from Solanum tuberosum through anther culture were characterized for nDNA variation, phenotypic variation and nuclear microsatellite polymorphism. Androgenic (di)haploids were also characterized for late blight resistance. The (di)haploid C-13 was derived from Indian tetraploid potato cv. Kufri Chipsona-2, while D4 from TPS (true potato seed) parental line JTH/C-107, which is an interspecific hybrid between Indian tetraploid cv. Kufri Jyoti and diploid (2n = 2x = 24) cultivated species S. phureja Juz. & Buk. IVP-35. C-13 and D4 (both male-fertile) could be distinguished from their corresponding tetraploid anther donors based on plant height, shoot number, terminal leaflet length and width, leaf ratio, anther length, pollen diameter and corolla width and radius. A complete reversal of flower color occurred in D4, and C-13 was highly resistant to late blight. Most interestingly, about 3–7% increase in nDNA content occurred in most of the anther-derived tetraploids. Both the androgenic (di)haploids and their anther donors had unique genotypes at the microsatellite loci POTM1-2, STM0015 and STM0019b. However, the nine anther-derived tetraploids shared the same allelic profiles with their anther donor JTH/C-107 at all the microsatellite loci, except at STM0019a where they were characterized by the absence of a standard donor allele (186-bp). A typical (di)haploid-specific allele was detected for the locus STWAX-2 where the standard donor alleles were replaced by a 230-bp allele in both C-13 and D4. The over-expression of microsatellite variation in D4 that also shows triallelic profiles at the microsatellite loci POTM1-2 and STM0015 can perhaps be attributed to its chimeric structure, which might have been formed through incomplete fusion of two different pro-embryos during the first steps of microspore division.