Evolution of tandem repeats in chili pepper genomes (Capsicum, Solanaceae).

CARRIZO GARCÍA C.; KAPETANOVIC, VILDANA; SCHNEEWEISS H.

Dresden

Encuentro; GPZ Meeting of the Working Group Cytogenetics; 2019

Capsicumis a genus belonging to the nightshade family (Solanaceae) and fiveof 35 species of peppers are cultivated worldwide. The genus isexclusively diploid with two phylogenetically informative basechromosome numbers (x=12 and 13). Comparative analyses of repetitive DNA composition of 23species representing major phylogenetic clades conducted using NGSskimming data and RepeatExplorer revealed that gypsyretrotransposons dominated and were largely responsible for 8-foldgenome size variation in the genus (0.8 to 7.7 pg). Tandem repeatswere second most dynamic class of repeats with 15 abundant satelliteDNA families recovered across the genus. FISH analyses of thelocalization and dynamics of rDNAs and the subset of satellite DNAfamilies in the species representing all four major clades revealedthat each group possesses unique set and localization of tandemrepeats. One locus of 5S rDNA was consistently found in all but onespecies, C.tovarii,in which two subterminal signals were recovered in all chromosomes.One or two major 35S rDNA loci were recovered in all species, butsome taxa possessed up to 20 35SrDNA-FISH signals. The additional 35Sand 5S rDNAs signals likely represented satellite DNA(s) originatingfrom spacer regions of functional rDNAs. Mapping of satellite DNAfamilies in all species showed that putative rDNA-derived satellitesare likely of multiple independent origins in different phylogeneticclades. High dynamics but also clear phylogenetic signal of thepresence and localization of tandem repeats allows hypotheses ofgenome evolution in Capsicumto be formulated.