25S-18S rDNA IGS of Capsicum: molecular structure and comparison

GRABIELE, M.; DEBAT, H. J.; MOSCONE, E. A.; DUCASSE, D. A.

PLANT SYSTEMATICS AND EVOLUTION

SPRINGER WIEN

Lugar: Viena; Año: 2010

0378-2697

The primary and secondary structures of the intergenic spacer (IGS) between the 3´-end of 25S rRNA gene and the 5´-end of 18S rRNA gene are described for the cultivated chili pepper Capsicum pubescens. The recognized functional IGS is 2078 bp in length and according to nucleotide base composition, regulatory elements and conserved and repeated sequences can be divided into seven structural regions (SRI-VII). SRI possess three copies of GAGGTTTTT-like motif, probable transcription termination site in Solanaceae; at 3´-end, there are 21 bp identical to 18S rRNA. SRII is formed by fourty-seven repeats of CACCATGG-like motives, the shortest ones found in plants rDNA yet. SRIII is highly AT-rich, preceding SRIV, a highly conserved region in Solanaceae containing the transcription initiation site (TIS) TATATAAGGGGGG. The external transcribed spacer (ETS) is 966 bp in length. SRV-VII, dowstream the TIS, possess eight inverted repeats and three predicted stem-loops are pri-miRNA-like. Intragenomic variation is presented and data is compared with already characterized Solanaceae 25S-18S rDNA IGS.