Prospecção de genes PR – 5 em fruteiras nativas ou adaptadas ao semiárido paraibano.

Abstract

PR-5 genes are important for biotechnological applications to present relevant antifungal/antioomycetal and drought resistance activities. Genomic studies from Semiarid plants are rare, including economically interesting fruit species, although these plants have genes that are evolutionarily adapted to the region. In this context, the objective was to prospect PR-5 genes in fruit plants present in the Paraiba Semiarid. The prospecting was carried out on two levels, in silico and in plant, by using public genomic databank and initial steps of the isolation of PR-5 genes from Paraiba Semiarid fruit plant genomes, respectively. Prospecting in silico led to the discovery that there are no sequence deposited in GenBank/NCBI named "PR-5", “thaumatin", “osmotin" and "pathogenesis-related" versus names for 06 plant families or plant scientific names for 08 Semiarid fruit plant, while in plantGDB there is only one of the surveyed family Caricacea, referring to the functional genome of transgenic papaya fruit tree (Carica papaya) cultivar “SunUP” resistant to virus. The PR-5 sequences found in that genome were found by keywords "thaumatin" or "osmotin" and, in most cases, are incomplete or inferior quality, being unable to identify complete genes, an exception for a gene that was named CpTLP. This gene encodes a potentially acidic protein thaumatin-like protein, sharing characteristics and high amino acid sequence similarities with other PR-5 proteins from GenBank database. A model built for mature CpTLP was significantly satisfactory and apparently functional, presenting 8 disulfide bonds formed by 16 conserved cysteines in the PR-5 family, and visibly characteristic active site. Prospecting in planta lead to obtaining of DNAs from 4 fruit species presenting sufficient quality and quantity for PCR amplification of specific gene fragments expected to PR-5 genes.