25S-18S ribosomal nature of the not NOR-associated highly GC-rich heterochromatin of chili peppers (Capsicum-Solanaceae)

GRABIELE MAURO; DEBAT H J; J. G. SEIJO; D. A. DUCASSE; SCALDAFERRO, M. A.; MOSCONE, E. A.; MARTÍ, D

Oro Verde, Entre Ríos

Congreso; 3er. Congreso Argentino de Bioinformática y Biología Computacional.; 2012

Facultad de Ingeniería ? Universidad Nacional de Entre Ríos

25S-18S ribosomal nature of the not NOR-associated highly GC-rich heterochromatin of chili peppers (Capsicum-Solanaceae) Mauro Grabiele1, Humberto Debat2, Marisel Scaldaferro3, Guillermo Seijo4, Daniel Ducasse2, Eduardo Moscone3, Dardo Martí1 1Instituto de Biología Subtropical (IBS-UNaM), Posadas, Misiones, 3300, Argentina 2Instituto de Fitopatología y Fisiología Vegetal (IFFIVE-INTA), Córdoba, 5119, Argentina 3Instituto Multidisciplinario de Biología Vegetal (IMBIV-UNC), Córdoba, 5000, Argentina 4Instituto de Botánica del Nordeste (IBONE-UNNE), Corrientes, 3400, Argentina Background Highly GC-rich heterochromatin (Het) is a universal component of the genome of chili peppers [1]. Fluorescent in situ hybridization (FISH) patterns using Arabidopsis and wheat derived ribosomal (rDNA) probes, embracing rRNA genes and intergenic spacer (IGS) with repetitive blocks segments, revealed a priori co-localization of rDNA and Het regions in Capsicum which promoted a further characterization of the 25S-18S rDNA unit in the genus [2] and the present work. Material and methods To reveal the unambiguous nature of the Het of chili peppers, combined bioinformatics (Database searching, sequence alignments, primary and secondary structures analysis) molecular cytogenetics (FISH) and molecular biology (PCR amplification, restriction enzymes assays, cloning and sequencing) approaches were carried out in 8 taxa representatives of the major lineages of Capsicum. Results A definite FISH co-localization pattern of Capsicum derived rDNA genes (18S, 25S, 5.8S) and spacers (ITS, IGS) probes and Het is exclusive for chili peppers based on x=12. FISH pattern of pCp200/33 probe, a mutated IGS element likely affecting rDNA transcripton, imitate that of rDNA/Het excluding the active NORs.