Chromosome doubling in monohaploid and dihaploid potatoes by regeneration from cultured leaf explants (original) (raw)

In vitro shoot regeneration and chromosome doubling in 2X and 3X potato clones

American potato journal, 1992

The possibility of scaling ploidy levels up and down offers several advantages for genetic studies and breeding work in potato. Shoot regeneration and chromosome doubling in plants regenerated from in vitro cultures were investigated in 4 diploid (2n= 2x= 24) and 2 triploid (2n= 3x= 36) clones. Internode and leaf explants were taken from plants propagated either in vitro as shoot cultures, or in vivo in a greenhouse. Two regeneration procedures were compared. Regeneration frequencies were significantly higher using a two-step regeneration protocol and from leaf explants, while doubling was more efficient starting from in vivo grown plants. No doubling was observed in triploid clones. Considering altogether the percentage of regeneration and doubling, and the number of shoots regenerated per explant, the most efficient conditions were considered leaf explants taken from in vivo grown plants, and cultured according to a two-step regeneration protocol.

Improvements in regeneration from protoplasts of potato and studies on chromosome stability

TAG Theoretical and Applied Genetics, 1986

Regeneration of plants from protoplasts of potato (Solanum tuberosum) cv. 'Maris Bard' has been achieved from four different initial culture media (ET2, ET3, CLG, VkCLG). These media differed in their hormone, salt and sugar content. Plating efficiencies were highest in the VkCLG medium, but no correlation was found between plating efficiency and regeneration frequency (i.e. the percentage of calli producing shoots). Regeneration frequencies were high on all four media; up to 95% on ET3. Chromosome counts of up to 50 regenerants selected at random from the four treatments showed no significant differences between any of the treatments, in the proportions of plants which were euploid (48), aneuploid at the tetraploid level (48+), and aneuploid with high chromosome numbers (48 + +). Highly significant differences were present, however, between shoots which rooted quickly (predominantly euploid) and those which rooted only after transfer to a rooting medium (predominantly 48+ +). Overall more than 60% of the regenerants were normal (2n=4x=48) and this is a considerable improvement on our earlier work in this cultivar (4% normal). These findings are discussed in relation to factors affecting chromosome stability. Chromosome structural rearrangements are also described.

Cytological investigations in diploid potato (Solanum spp.)

Chromosome Botany, 2016

Meiotic behaviour of plant chromosomes is influenced by both genetic and environmental factors. The present paper shows the affect of abnormal meiosis on pollen fertility. Meiotic restitution is considered to be a common mechanism of polyploidization in plants and hence is one of the most important processes in plant speciation. Pollen mother cells (PMCs) of diploid potato from anthers at different stages of meiotic process were analyzed for their chromosomal behaviour and irregularities. Pollen morphology was also studied through SEM as it is significantly helpful at the generic and specific level. Various meiotic irregularities were observed: univalent and multivalent formation, chromosome bridges, fragments, lagging chromosomes etc. B-chromosome was first time reported in wild diploid potato, though the frequency of the same was less. Specie was identified as Solanum chacoense.

Analysis of tetraploid-diploid hybrids in cultivated potatoes

Potato Research, 1977

Progeny families of 4x -2x hybrids between Group Tuberosum and Group Phureja-haploid Group Tuberosum hybrids were evaluated under simulated commercial agricultural practices in 1974 and 1975. The range of the observed values for the 4x-2x hybrids exceeded the range of the 4x parents for nearly all measured traits. The mean for total yield of the 4x-2x hybrids was equal to ( 1974 experiment) or significantly higher (1975 experiment) than the mean of the 4x parents. In the 1975 experirnent 17.8"o of the 4x-2x hybrids produced a higher total yield than the highest yielding 4x parents. The 4x 2x hybrids exhibited a significantly lower mean than the 4x parents for marketable yield and tuber weight but transgressive segregants were found for these traits in both experiments. The heterosis and variability of the hybrids indicates that this breeding method is a potentially powerful tool in potato improvement.

Genomic Outcomes of Haploid Induction Crosses in Potato (Solanum tuberosum L.)

The challenges of breeding autotetraploid potato (Solanum tuberosum) have motivated the development of alternative breeding strategies. A common approach is to obtain uniparental dihaploids from a tetraploid of interest through pollination with S. tuberosum Andigenum Group (formerly S. phureja) cultivars. The mechanism underlying haploid formation of these crosses is unclear, and questions regarding the frequency of paternal DNA transmission remain. Previous reports described aneuploid and euploid progeny, which, in some cases, displayed genetic markers from the haploid inducer. Here, we surveyed a population of 167 presumed dihaploids for large-scale structural variation that would underlie chromosomal addition from the haploid inducer, and for small-scale introgression of genetic markers. In 19 progeny, we detected ten of the twelve possible trisomies and, in all cases, demonstrated the non-inducer parent origin of the additional chromosome. Deep sequencing indicated that occasion...

Genetics and Cytogenetics of the Potato

The Potato Crop, 2020

Tetraploid potato (Solanum tuberosum L.) is a genetically complex, polysomic tetraploid (2n = 4x = 48), highly heterozygous crop, which makes genetic research and utilization of potato wild relatives in breeding difficult. Notwithstanding, the potato reference genome, transcriptome, resequencing, and single nucleotide polymorphism (SNP) genotyping analysis provide new means for increasing the understanding of potato genetics and cytogenetics. An alternative approach based on the use of haploids (2n = 2x = 24) produced from tetraploid S. tuberosum along with available genomic tools have also provided means to get insights into natural mechanisms that take place within the genetic load and chromosomal architecture of tetraploid potatoes. This chapter gives an overview of potato genetic and cytogenetic research relevant to germplasm enhancement and breeding. The reader will encounter findings that open new doors to explore inbred line breeding in potato and strategic roads to access the diversity across the polyploid series of this crop's genetic resources. The text includes classical concepts and explains the foundations of potato genetics and mechanisms underlying natural cytogenetics phenomena as well as their breeding applications. Hopefully, this chapter will encourage further research that will lead to successfully develop broad-based potato breeding populations and derive highly heterozygous cultivars that meet the demands of having a resilient crop addressing the threats brought by climate change.

Ploidy level manipulations in potato through sexual hybridisation

Annals of Applied Biology, 2005

There is no better use of sexual reproduction in regard to breeding and genetic research than the ploidy level manipulations possible in the potato and its relatives. Unique reproductive characteristics of tuber-bearing Solanum species make possible: the production of gametes with unreduced chromosome number; the presence of an endosperm dosage system that regulates success of interploidy/interspecific crosses; the possibility to easily extract maternal haploids following crosses with S. phureja. This paper reviews results obtained in scaling genomic multiples up and down in potato, and relates these manipulations to breeding strategies for the genetic improvement of the cultivated potato. Several ploidy series have been developed, ranging from the monoploid to the hexaploid level. Cultivated tetraploids were scaled down to the diploid and monoploid level by haploidy. Scaling upward was achieved by sexual polyploidisation via 2n gametes that resulted in triploid, tetraploid, pentaploid, and hexaploid genotypes with a broad genetic base. Altogether, the success of ploidy level manipulations constitutes further proof that sexual polyploidisation played an important role in the polyploid evolution of Solanum species, and supports the idea that gene flow can be relatively easily accomplished through interploid and bridge crosses.

Postmeiotic restitution in 2n-egg formation of diploid potato

Heredity, 1998

Four diploid (2n = 2x = 24) interspecific F 1 hybrids of tuberous Solanum species were tested for the modes of origin of 2n-eggs. The four hybrids were heterozygous for the genetic marker amylose-free starch (Amf/amf) on chromosome 8. By crossing these hybrids with tetraploid S. tuberosum parents (2n = 4x = 48) that were nulliplex for this marker, i.e. Amf/amf amf/ amf/amf/amf crosses, tetraploid progenies were generated and classified for starch phenotypes of microspores. Based on the segregation of the amf marker gene, the tetraploid progenies were classified into nulliplex, simplex and duplex genotypes. In the progenies of three F 1 hybrids, the simplex genotypes predominated and the origin of 2n-eggs could be explained as the result of second division restitution (SDR). But in the progeny of one F 1 hybrid (a S. microdontum S. tuberosum hybrid), there were only nulliplex and duplex genotypes, indicating complete homozygosity of the 2n-eggs (Amf/Amf or amf/amf) for this locus. In order to genotype the 2n-eggs also for other loci on the same chromosome, a tetraploid progeny was generated from a cross between this hybrid and a tetraploid S. tuberosum parent (Tetra 4) and analysed for four RFLP loci on chromosome 8. This analysis showed that all 2n-eggs of the S. microdontum S. tuberosum hybrid were homozygous for all four loci, as was observed for the amf locus. From the same analysis it was evident that crossovers had occurred between the two genomes of this F 1 hybrid. These homozygous and recombinant genotypes indicated that the 2n-eggs had originated from the doubling of the chromosome number in the normal haploid products of meiosis. Following the terminology of first and second division restitution (FDR and SDR), this new mode of origin of 2n-eggs in diploid potato is called post-meiotic restitution (PMR).