Respostas moleculares, histológicas e histoquímicas de cultivares de bananeira desafiadas com isolados de Fusarium oxysporum F. Sp. cubense com diferentes níveis de virulência

Abstract

Banana is one of the most consumed foods in the world and one of the main commodities for export in several countries. In recent years, one of the biggest limitations for fruit production is Fusarium wilt caused by the soil-dwelling fungus Fusarium oxysporum f. sp. cubense (Foc), mainly due to the highly aggressive strain of the pathogen, called tropical race 4 (TR4) whose epidemic is in pandemic proportions. Due to its saprophytic habits and because it presents many evolutionary mechanisms, resulting in high genetic diversity, the management of Foc in infested areas is difficult. Genetic improvement to obtain resistant cultivars is the most viable and efficient strategy. Thus, this work initially proposes a systematic review of the literature generated in the last ten years on the genetic improvement of Musa spp. for resistance to Fusarium wilt. To this end, a protocol was generated and followed in order to comply with the standards described in the preferred report items for systematic reviews and meta-analyses (PRISMA). After searching for articles in different academic databases, using a standardized search string and predefined inclusion and exclusion criteria, 95 articles were included in the systemic analysis of the review. With this, it was verified that the information obtained after the genome sequencing of Musa spp. is a source for obtaining resistant cultivars, mainly by evaluating the transcriptome data of banana after infection with Foc. The review also highlights the sources of resistance to Foc race 1 (R1) and Foc TR4 in germplasm of Musa spp. and transgenesis technique as the most frequent approach to crop improvement. This work also aims to analyze the interaction of the pathogen Foc with its host Musa spp. at molecular, histological and histochemical levels, where three isolates of Foc representative of race 1 (R1), subtropical race 4 (ST4) and the isolate 229A, putative ST4, were inoculated in two cultivars of the Prata type (Prata-Anã and BRS Platina) and in a cultivar of the Cavendish type (Grand Naine). The results showed seven genes induced in 'BRS Platina', as well as increased presence of cellulose, phenolic compounds and calcium oxalate crystals, suggesting their important roles in the incompatible interactions between resistant banana and Foc ST4 and R1. But, these defense responses were suppressed or reduced mainly by an isolate with higher virulence in 'Prata-Anã' and 'Grand Naine'. Thus, the cultivar BRS Platina will be the target of further research to verify its interaction with Foc TR4. In conclusion, this work offers a compilation of data and new perspectives on the genetic improvement of Musa spp. for resistance to Fusarium wilt.