Cloning, in silico structural characterization and expression analysis of MfAtr4, an ABC transporter from the banana pathogen Mycosphaerella fijiensis

ABC transporters are membrane proteins that use the energy released from the hydrolysis of ATP to drive the transport of compounds across biological membranes. In some plants, pathogenic fungi ABC transporters play a role as virulence factors by mediating the export of plant defense compounds or fungal virulence factors. Mycosphaerella fijiensis, the causal agent of black Sigatoka disease in banana, is the main constraint for the banana industry worldwide. So far, little is known about molecular mechanism that it uses to infect the host. In this study, degenerated primers designed from fungal ABC transporters known to be involved in virulence were used to isolate homologs from M. fijiensis. Here, we reported the full cloning of MfAtr4 a putative ortholog of MgAtr4, an ABC transporter of the related Mycosphaerella graminicola with a function in virulence. Similarities and differences with its presumed ortholog MgAtr4 are described, and the putative function of MfAtr4 are discussed. Analysis of MfAtr4 gene expression in field banana samples exhibiting visible symptoms of black Sigatoka disease indicated a higher expression of MfAtr4 during the first symptomatic stages in comparison to the late necrotrophic phases, suggesting a role for MfAtr4 in the early stages of pathogenic development of M. fijiensis.Key words: ABC transporters, virulence factors, MgAtr4 ortholog, Mycosphaerella fijiensis, black Sigatoka, Musa sp

Embryonic dormancy in seeds of Bactris gasipaes Kunth (peach-palm)

Bactris gasipaes is a domesticated palm whose fruits are of great importance for the Amazonian people and whose heart of palm is also receiving economic interest in other brazilian and Latin America regions. The aim of this study was verify embryonic dormancy and its correlation with first cataphyll emergence in B. gasipaes seeds collected from four plants at Manaus city and four others at Coari city, both in the Amazonas state, Brazil. After extraction and cleaning, some of the seeds (4 replications of 25 per plant) were sown in a seedbed with a sawdust and sand mixture as substrate, and embryos (4 replications of 10 per plant), after extraction, were inoculated into half strength Murashige and Skoog cultures. Were used 100 seeds and 40 embryo per treatment. Whole seed and embryo germination varied between the different source plants and locations, with the greatest difference observed for the emergence of first cataphyll from seeds in the seedbed. For the most part of variables, results of seed and embryo were positively associated, namely, as one went up the other also, and vice versa. These results suggesting that, at least in part, seed dormancy in Bactris gasipaes is associated with embryonic dormancy. © 2017, Associacao Brasileira de Tecnologia de Sementes. All rights reserved

Saccharification with Phanerochaete chrysosporium and Pleurotus ostreatus enzymatic extracts of pretreated banana waste

Lignocellulosic biomass has a great potential as raw material for second and third generation biofuels since it is the most abundant carbohydrate on earth and the main component of agricultural waste; however, saccharification of lignocellulosic biomass is crucial for the establishment of a carbohydratebased economy. The use of fungal enzymes is the preferred procedure for lignocellulosic saccharification. Fungi such as basidiomycetes (e.g Phanerochaete chrysosporium) produce cellulolytic/hemicellulolytic and ligninolytic enzymes, which are responsible for lignocellulose degradation. In this study the saccharification of banana flour prepared from pseudostem and green non commercial-grade fruit (1:1), two of the main agro-waste of banana industry was investigated. The material was pretreated by physical and chemical processes including drying and grinding, followed by 3% HCl or 3% NaOH hydrolysis, or a sequential pretreatment with 3% HCl first and then 3% NaOH and heated at 121°C, at 15 Lb/in2 for 15 min. The highest concentration of reducing sugars (RS) was obtained with acid hydrolysis (42.41 gL-1). Crude cellulolytic-ligninolytic enzymatic extracts from Pleurotus ostreatus and P. chrysosporium cultured on banana waste as the only carbon source were prepared and used for the saccharification. Surprisingly, P. chrysosporium crude extract produced a decrease in RS (2.27 gL-1). Although P. ostreatus cellulose activity (17,777.78 UL-1) was almost half compared to P. chrysosporium’s (31,296.30 UL-1), the former produced an increment in the release of RS (63.65 gL-1). In Mexico, banana is one of the main crops and generates large agricultural waste after harvest. According to the results obtained with acid-heat pretreatment followed by saccharification with P. ostreatus enzymatic crude extract, banana agro-waste can be considered as a potential feedstock for RS-based bioproducts like bioethanol.Key words: Banana waste, lignocellulosic, pretreatments, saccharification, reducing sugars