title: Distribution of 45S rDNA in Modern Rose Cultivars (Rosa hybrida), Rosa rugosa, and Their Interspecific Hybrids Revealed by Fluorescence in situ Hybridization.
abstract: To elucidate the evolutionary dynamics of the location and number of rDNA loci in the process of polyploidization in the genus Rosa, we examined 45S rDNA sites in the chromosomes of 6 modern rose cultivars (R. hybrida), 5 R. rugosa cultivars, and 20 hybrid progenies by fluorescence in situ hybridization. Variation in the number of rDNA sites in parents and their interspecific hybrids was detected. As expected, 4 rDNA sites were observed in the genomes of 4 modern rose cultivars, while 3 hybridization sites were observed in the 2 others. Two expected rDNA sites were found in 2 R. rugosa cultivars, while in the other 3 R. rugosa cultivars 4 sites were present. Among the 20 R. hybrida × R. rugosa offspring, 13 carried the expected number of rDNA sites, and 1 had 6 hybridization sites, which exceeded the expected number by far. The other 6 offspring had either 2 or 3 hybridization sites, which was less than expected. Differences in the number of rDNA loci were observed in interspecific offspring, indicating that rDNA loci exhibit instability after distant hybridization events. Abnormal chromosome pairing may be the main factor explaining the variation in rDNA sites during polyploidization.
authors: Beijing Key Laboratory of Ornamental Plants Germplasm Innovation &amp; Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment and College of Landscape Architecture, Beijing Forestry University, Beijing, PR China.
authors: Xiao-Liu
authors: XL
authors: Ding
authors: Ting-Liang
authors: TL
authors: Xu
authors: Jing
authors: J
authors: Wang
authors: Le
authors: L
authors: Luo
authors: Chao
authors: C
authors: Yu
authors: Gui-Min
authors: GM
authors: Dong
authors: Hui-Tang
authors: HT
authors: Pan
authors: Qi-Xiang
authors: QX
authors: Zhang
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D019143:Evolution, Molecular; D005638:Fruit; D018525:Germination; D006824:Hybridization, Genetic; D017404:In Situ Hybridization, Fluorescence; D008677:Metaphase; D011123:Polyploidy; D012335:RNA, Ribosomal / Q000235:genetics*; D027826:Rosa / Q000145:classification* / Q000235:genetics*
chemical_list: D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; C088179:RNA, ribosomal, 45S