Karyotype analysis and physical mapping of 45S rDNA in eight species of Sophora, Robinia, and Amorpha

Abstract

The karyotype analysis and physical locations of 45S rDNA were carried out by means of fluorescence in situ hybridization in three species, and two forms of Sophora, two species of Robina, and one species of Amorpha. S. japonica L., S. japonica L. f. oligophylla Franch., S. japonica L. f. pendula Loud., and S. xanthantha C. Y. Ma. are all tetraploids with 2n = 28. There were four 45S rDNA sites in pericentromeric regions of two pairs of chromosomes in each of them. S. rubriflora Tsoong. is a triploid with 2n = 21, and three sites were located in each satellite of group 5 chromosomes. In R. pseudoacacia L. (2n = 2x = 22), we examined four intensive signals in telomeric regions of two pairs of satellite chromosomes. In R. hispida L. (2n = 2x = 30), there were four other signals in centromeric regions besides those like in R. pseudoacacia. Amorpha fruticosa L. has most chromosomes (2n = 40) among the eight materials, however, there were only six 45S rDNA loci and they laid in centromeric regions, and satellites of three pairs of chromosomes. 45S rDNA is a valuable chromosomal landmark in karyotype analysis. The distribution and genomic organization of rDNA in the three genera were also discussed.

Five Fabaceae Karyotype and Phylogenetic Relationship Analysis Based on Oligo-FISH for 5S rDNA and (AG3T3)3

“…As a relatively stable feature, chromosome data is an important means to study chromosome aberrations, cell functions and taxonomic relationships in plant species [5]. The chromosome numbers of R. pseudoacacia, R. pseudoacacia 'Idaho', R. pseudoacacia f. decaisneana, S. japonicum, A. fruticose in this study were consistent with those of previous studies [27][28][29][30][31]. However, the karyotype formula is different.…”

“…However, the karyotype formula is different. Liu et al [28] believed that S. japonicum 2n = 4x = 28 = 18m + 10sm cytotype 2B, R. pseudoacacia 2n = 2x = 22 = 4m + 8sm + 10st cytotype 3B and A. fruticose 2n = 2x = 40 = 32m + 8sm cytotype 1A, only R. pseudoacacia and A. fruticose have appendages, whereas the satellite chromosome of R. pseudoacacia considered by Chen [27] as short arms. Lv and Wang [30] used the traditional production method and obtained the karyotype formula 2n = 4x = 40= 30m + 8sm + 2st of A. fruticose, without satellite, and the cytotype was 2A.…”

“…Lv and Wang [30] and Shi et al [31] did not use FISH technique, but used traditional filmmaking techniques, resulting in unclear chromosome images. Liu et al [28] used FISH technology, but the method was different in the early stage of production, which may lead to insufficient shrinkage of chromosomes. Secondly, one possible reason for the length difference may be the use of different tools to calculate information about chromosome arms and shapes [5].…”

The intergenic spacer region of the rDNA in Haplopappus gracilis (Nutt.) Gray

“…4a, b). Also, in Quercus species, Zoldos et al (1999) evidenced after in situ hybridization with rDNA probes that the size and strength of the hybridization signals differed between homologous site of NOR-1 and Liu et al (2006), studying the physical location of 45S rDNA, founded differences between homologues sites in several species of Sophora, Robinia and Amorpha. The heteromorphism of homologuous NORs may suggest the presence of a variable number of ribosomal genes that can be related to the amplification, deletion or unequal crossing over of genes.…”

Multicolor FISH analysis of rDNA and telomere on spinach

“…45S rDNA is composed of 18S, 5.8S and 25S rDNA. So far, many studies have proved that, in many species, 45S rDNA is mainly located on the nuclear organization region (NOR), that is the SC region (Xu et al, 2007;Liu et al, 2005). 25S rDNA is a part of the 45S rDNA; it locates on the NOR too.…”