Comparative analysis of structure and variability of the ribosomal genes of the Peanut and their wild diploids parentals for evolutionary studies

CHALUP L.; ROBLEDO G.; SAMOLUK SS.; SEIJO G.; AGOSTINI F.

Mendoza

Congreso; A2B2C 10th Congress; 2019

A2B2C

Comparative analysis of structure and variability of the ribosomal genes of thePeanut and their wild diploids parentals for evolutionary studiesChalup L, Samoluk SS, Agostini F, Robledo G, Seijo G*.Northeast Botanical Institute (IBONE), UNNE?CONICET; FACENA, National Universityof Northeast, Corrientes, Argentina. laurachalup@gmail.comThe ribosomal DNA repeats are an important fraction of the repetitive DNA of thegenomes, which have a direct role in gene expression. 45S rDNA repeat unit containsthe sequence for the 26S, 5.8S and 18S rRNA genes, as well as two transcribedspacers (ITS1 and ITS2) and a large intergenic spacer (IGS). Likewise, the 5S rDNA isorganized in a transcribable region and a non-transcribable (NTS) region. Both rDNArepeats are organized into arrays and contains hundreds to thousands of repeats.Here, we analysed the structure of the ribosomal genes present in A. hypogaea(AABB), A. monticola (AABB) and their diploid parental species, A. duranensis (AA)and A. ipaënsis (BB) for future studies on amphiplasty and other effects ofpolyploidization. The characterization of the structures of the rDNA units of the 5S lociwas highly conserved. However, the structure of the 45S sequence showed somespecies-specific differences between diploids. A small fraction of 79 bp towards the 5´and another 300 bp fraction towards the 3´ of the promoter were exclusive of A.ipaënsis. Differences in the composition and structure of another repetitive region werealso observed in the ETS. Both 45S rDNA versions were recovered from theallopolyploids. Ongoing research is centered in quantifying the copy number of both45S versions in the allotetraploids to provide additional information for the analysis ofgenome specific NOR activation.