GENETIC CODE CHANGE IN AT-RICH PLASTID GENOMES OF TWO HOLOPARASITIC PLANTS (BALANOPHORACEAE)

CERIOTTI LUIS FEDERICO; ROULET MARIA EMILIA; GARCIA LAURA EVANGELINA; SANCHEZ PUERTA MARIA VIRGINIA

Mendoza

Congreso; XVII CONGRESO LATINOAMERICANO DE GENÉTICA; 2019

The family Balanophoraceae (order Santalales)encompasses 14 genera of obligate root holoparasites(i.e. completely nonphotosyntheticand hostdependent plants). As in other nonphotosyntheticangiosperms, plastid genomes (ptDNA) inBalanophora spp. are characterized by a high degreeof reduction in size and gene content and low levelsof GC content. In addition, a novel type of geneticcode change was discovered, in which the TAG codoncodes for tryptophan instead of being a stop-codon.In this study, we sequenced and analyzed ptDNAregions of Lophophytum mirabile and Ombrophytumsubterraneum (Balanophoraceae). Total DNAfrom both species was sequenced with Illuminatechnology. Also, RNAseq was performed for L.mirabile. The ptDNA assembly was carried out basedon genomic and transcriptomic paired-end reads.Plastid contigs of L. mirabile and O. subterraneumhadan average AT content of 79.55% and 81.75%,respectively. Ribosomal and protein coding genesshowed high substitution rates, as in other membersof the family. We identified a different change inthe genetic code of both ptDNAs; in this case TGA(typically a stop codon) codes for tryptophan. Itrepresents the second case of a genetic-code changein land-plant ptDNAs. RNA editing was not found inthe sequenced plastid genes.