Karyotypic Evolution and Molecular Cytogenetic Analysis of Solanum pinnatisectum, a New Source of Resistance to Late Blight and Colorado Potato Beetle in Potato

Abstract

SummaryTo efficiently transfer important disease and insect resistance traits from diploid Mexican wild species Solanum pinnatisectum to tetraploid cultivated Solanum tuberosum, molecular cytogenetic and karyotypic analyses were carried out to examine the degree of chromosomal and genomic variation between these 2 species. The results demonstrated that the chromosome complement in S. pinnatisectum was predominantly metacentric and submetacentric, while S. tuberosum showed prominent subtelocentric and telocentric chromosomes. It appears that karyotype evolution from diploid to tetraploid originates through chromosome rearrangements, involving mainly deletions or multiplication at the same ploidy level. Fluorescence in situ hybridization (FISH) using 18S-5.8S-26S ribosomal RNA (rDNA) as a probe demonstrated that both diploid and tetraploid potato species had a single nucleolus organizer region (NOR) locus. However, the localization of the rDNA sites in one of the 2 accessions of S. pinnatisectum was characterized by a pair of morphologically distinct chromosomes, in which one was a submetacentric chromosome, while its homologous partner was a subtelocentric chromosome, which was very similar to that observed in tetraploid potato. This indicated that chromosome variation in structural alterations and nuclear DNA content, as well as loss or addition of highly repetitive sequences could play a role in potato evolution and development of new cultivars. This study offers a useful molecular cytogenetic marker for species identification, chromosome inheritance and potential introgression in future intergenetic hybridization experiments with Mexican wild potato species.

Heterochromatin and rDNA patterns in Solanum species of the Morelloid and Dulcamaroid clades (Solanaceae)

“…Solanum chenopodioides, S. palitans, and S. pilcomayense showed exclusive bands associated with NORs; the same pattern was found by Melo et al (2011) in a population of S. nigrum. On the other hand, we found telomeric bands not associated with NORs in S. aloysiifolium, S. americanum, S. hastatilobum, S. triflorum, and S. salicifolium as previously reported in different in Solanum (Li et al 2006;Brasileiro-Vidal et al 2009;Rego et al 2009;Melo et al 2011;Chiarini et al 2014). In the Morelloid clade, this was previously detected in four species Jiang et al 2011;Melo et al 2011) including S. americanum studied here.…”

Identifying Resistance to the Colorado Potato Beetle (Leptinotarsa decemlineata Say) in Potato Germplasm: Review Update

“…The structure and abundance of glandular trichomes are another biological characteristic that contributes to insect resistance in Solanum spp. (Gibson, 1971;Gibson and Turner, 1977;Tingey and Gibson, 1978;Tingey and Sinden, 1982; Pelletier et al, 1999;Chen et al, 2003;Li et al, 2006…”