Localization of the 5S and 45S rDNA Sites and cpDNA Sequence Analysis in Species of the Quadrifaria Group of Paspalum (Poaceae, Paniceae)

Takada

J. Japan. Soc. Hort. Sci.

et al. 2012

Fluorescent banding patterns of pear chromosomes were determined from samples taken from root tips of openpollinated seedlings of Pyrus pyrifolia (Burm. F) Nakai (Japanese pear), P. calleryana Decne. (Callery pear), P. pyrifolia × P. ussuriensis var. aromatica (a hybrid of Japanese pear and Iwateyamanashi), and P. mikawana Koidz. (Toyotomi Nashi). All accessions used in this study had 2n = 34 chromosomes. Chromomycin A 3 (CMA)-positive (+) bands were observed in telomeric positions of four chromosomes in all accessions. 4'-6-diamidino-2-phenylindole (DAPI)-negative bands (−) corresponded with CMA+ bands. Fluorescence in situ hybridization (FISH) was conducted using open-pollinated seedlings of 'Osa Gold' (Pyrus pyrifolia) and Toyotomi Nashi (P. mikawana) as materials. Four out of six 18S-5.8S-25S ribosomal RNA gene (rDNA) sites corresponded with CMA+/DAPI− bands. The 5S rDNA sites were detected in centromeric positions of two chromosomes. Two centromeric 5S rDNA and six telomeric 18S-5.8S-25S rDNA sites were located on different chromosomes as determined from the results of multi-color FISH.

Section: Resultsmentioning

confidence: 99%

Fluorescent Staining and Fluorescence in situ Hybridization of rDNA of Chromosomes in Pear (Pyrus spp.)

Takada

J. Japan. Soc. Hort. Sci.

et al. 2012

“…FISH signals with p Ta 71 do not exhibit variation in size among the different species studied. The presence of these sites in terminal regions of both chromosome arms is frequent in Angiosperms (e.g., Zhang and Sang, 1998;Benko-Iseppon and Morawetz, 2000;Vaio et al, 2005;Urdampilleta et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Karyotypes, heterochromatin, and physical mapping of 18S-26S rDNA in Cactaceae

Peñas

Urdampilleta

Bernardello

et al. 2009

Cytogenet Genome Res

Karyotype analyses in members of the four Cactaceae subfamilies were performed. Numbers and karyotype formula obtained were: Pereskioideae = Pereskiaaculeata(2n = 22; 10 m + 1 sm), Maihuenioideae = Maihuenia patagonica (2n = 22, 9 m + 2 sm; 2n = 44, 18 m + 4 sm), Opuntioideae = Cumulopuntia recurvata(2n = 44; 20 m + 2 sm), Cactoideae = Acanthocalycium spiniflorum (2n = 22; 10 m + 1 sm),Echinopsis tubiflora (2n = 22; 10 m + 1 sm), Trichocereus candicans (2n = 22, 22 m). Chromosomes were small, the average chromosome length was 2.3 μm. Diploid species and the tetraploid C. recurvata had one terminal satellite, whereas the remaining tetraploid species showed four satellited chromosomes. Karyotypes were symmetrical. No CMA^–/DAPI⁺ bands were detected, but CMA⁺/DAPI^– bands associated with NOR were always found. Pericentromeric heterochromatin was found in C. recurvata, A. spiniflorum, and the tetraploid cytotype of M. patagonica. The locations of the 18S-26S rDNA sites in all species coincided with CMA⁺/DAPI^– bands; the same occurred with the sizes and numbers of signals for each species. This technique was applied for the first time in metaphase chromosomes in cacti. NOR-bearing pair no.1 may be homeologous in all species examined. In Cactaceae, the 18S-26S loci seem to be highly conserved.

“…The only general rule to the direction of events is that tetraploids or higher ploidy levels are always derived from diploids or low ploidy levels. Among neopolyploids this assumption has been widely supported by FISH (Linares et al, 1998;Vaio et al, 2005) and GISH (Bennett, 1995), although in some other cases the diploid ancestors are unknown, are extinct or they have diverged since the hybridization/polyploidization event, as in the case of the B genome of common wheat (Petersen et al, 2006) or the D genome of oat (Linares et al, 1998).…”

Section: Chromosome Numbers and The Direction Of Evolutionmentioning

confidence: 98%

Chromosome numbers in plant cytotaxonomy: concepts and implications

Guerra¹

2008

Cytogenet Genome Res

260

171

Chromosome number is the karyotype feature most commonly used in cytotaxonomical analyses. The chromosome number can be a plesiomorphic characteristic of a large clade or a recurrent trait which arose independently in two or more clades. Some concepts regarding chromosome number variation, such as base number, aneuploidy, paleopolyploidy, and neopolyploidy have been used by different authors in quite different ways. Therefore, its use in cytotaxonomy and karyotype evolution deserves much attention. In this paper, these terms are reappraised and their meaning and implication for plant cytotaxonomy are discussed.