Eucalyptus grandis THIOREDOXINS, DIVERSITY AND GENE EXPRESSION

Abstract

Tree genomes have been sequenced in recent years providing a source of basic information on multigenic family characterization. Comparative genomics based on those complete genome sequences available in public database is an important tool providing useful information to progress on functional gene characterization. In this work, we focus on gene encoding for Thioredoxins (Trxs) in Eucalyptus grandis genome, which are oxidoreductase enzymes, involved in significant biochemical processes, above all the maintenance of cellular homeostasis. Here we investigate the diversity, structure and expression of these genes in eucalyptus. For this purpose, bioinformatics tools were employed, using public platforms data, to identify coding sequences and validate gene expression. Specific softwares were employed to characterize gene structure and expression. RT-PCR assays were carried out to specifically verify the expression of 4 cytoplasmic thioredoxin genes, observed in silico from leaf, phloem, xylem and apical meristem tissues. Twenty-two Trxs with characteristic and canonic active sites were identified, confirming the presence of all types of the three main groups already defined as plastidial (m, f, x, y, z) cytoplasmatic (h) and mitochondrial (o). However, differences in the number of genes per group were observed when compared with other tree genomes. The expression of these thioredoxin genes compared to some homologous genes presented divergent expression patterns compared to Arabidopis thaliana suggesting a functional specificity in eucalyptus, such as in the case of Eucgr.F01604 gene encoding an h1 cytoplasmic Trx, which presents a strong expression in conductor tissues.

Keywords: Thioredoxin; Comparative genomics; RNA-seq