Ribosomal DNA localization on Lathyrus species chromosomes by FISH

Hoda B.M Ali,Samira A Osman

doi:10.1186/s43141-020-00075-1

Abstract

BackgroundFluorescence In Situ Hybridization (FISH) played an essential role to locate the ribosomal RNA genes on the chromosomes that offered a new tool to study the chromosome structure and evolution in plant. The 45S and 5S rRNA genes are independent and localized at one or more loci per the chromosome complement, their positions along chromosomes offer useful markers for chromosome discriminations. In the current study FISH has been performed to locate 45S and 5S rRNA genes on the chromosomes of nine Lathyrus species belong to five different sections, all have chromosome number 2n=14, Lathyrus gorgoni Parl, Lathyrus hirsutus L., Lathyrus amphicarpos L., Lathyrus odoratus L., Lathyrus sphaericus Retz, Lathyrus incospicuus L, Lathyrus paranensis Burkart, Lathyrus nissolia L., and Lathyrus articulates L. ResultsThe revealed loci of 45S and 5S rDNA by FISH on metaphase chromosomes of the examined species were as follow: all of the studied species have one 45S rDNA locus and one 5S rDNA locus except L. odoratus L., L. amphicarpos L. and L. sphaericus Retz L. have two loci of 5S rDNA. Three out of the nine examined species have the loci of 45S and 5S rRNA genes on the opposite arms of the same chromosome (L. nissolia L., L. amphicarpos L., and L. incospicuus L.), while L. hirsutus L. has both loci on the same chromosome arm. The other five species showed the loci of the two types of rDNA on different chromosomes. ConclusionThe detected 5S and 45S rDNA loci in Lathyrus could be used as chromosomal markers to discriminate the chromosome pairs of the examined species. FISH could discriminate only one chromosome pair out of the seven pairs in three species, in L. hirsutus L., L. nissolia L. and L. incospicuus L., and two chromosome pairs in five species, in L. paranensis Burkart, L. odoratus L., L. amphicarpos L., L. gorgoni Parl. and L. articulatus L., while it could discriminate three chromosome pairs in L. sphaericus Retz. these results could contribute into the physical genome mapping of Lathyrus species and the evolution of rDNA patterns by FISH in the coming studies in future.

Highlights

Fluorescence In Situ Hybridization (FISH) played an essential role to locate the ribosomal RNA genes on the chromosomes that offered a new tool to study the chromosome structure and evolution in plant
The loci of 45S and 5S ribosomal DNAs (rDNA) probes as revealed by double-target FISH on metaphase chromosomes preparations of the nine examined species have been shown in Fig. 1, and their karyotypes are shown in Fig. 2, and Table 1
L. odoratus L. belong to section Lathyrus, has one stretched interstitial 45S Ribosomal RNA (rRNA) gene site on chromosome no. 4, which is distinguished with a big satellite, while two 5Sr RNA gene loci were observed in this species, one interstitial and one distal 5S rDNA on the short arm of chromosome pair no. 3 (Fig.1c)

Summary

Introduction

Fluorescence In Situ Hybridization (FISH) played an essential role to locate the ribosomal RNA genes on the chromosomes that offered a new tool to study the chromosome structure and evolution in plant. FISH has been used to localize a single copy gene on its position on a specific chromosome [29,30,31], by using bacterial artificial chromosome clones (BACs) clones was useful to paint specific chromosome [32,33,34,35], to reveal chromosomal inversion [36], or a translocation between the chromosomes of the different genomes in the allopolyploid hybrids [37], it was useful in designing species-specific DNA sequences (probes) to be tested on the related species, arising in comparative cytogenetic mapping among these species [38,39,40,41]

Results

Discussion

Conclusion