Mayra Acosta-Suárez

Bio: Mayra Acosta-Suárez is an academic researcher. The author has contributed to research in topics: Black sigatoka & Mycosphaerella. The author has an hindex of 6, co-authored 68 publications receiving 197 citations.

Analysis of expressed sequence tags derived from a compatible Mycosphaerella fijiensis–banana interaction

Abstract: Mycosphaerella fijiensis, a hemibiotrophic fungus, is the causal agent of black leaf streak disease, the most serious foliar disease of bananas and plantains. To analyze the compatible interaction of M. fijiensis with Musa spp., a suppression subtractive hybridization (SSH) cDNA library was constructed to identify transcripts induced at late stages of infection in the host and the pathogen. In addition, a full-length cDNA library was created from the same mRNA starting material as the SSH library. The SSH procedure was effective in identifying specific genes predicted to be involved in plant–fungal interactions and new information was obtained mainly about genes and pathways activated in the plant. Several plant genes predicted to be involved in the synthesis of phenylpropanoids and detoxification compounds were identified, as well as pathogenesis-related proteins that could be involved in the plant response against M. fijiensis infection. At late stages of infection, jasmonic acid and ethylene signaling transduction pathways appear to be active, which corresponds with the necrotrophic life style of M. fijiensis. Quantitative PCR experiments revealed that antifungal genes encoding PR proteins and GDSL-like lipase are only transiently induced 30 days post inoculation (dpi), indicating that the fungus is probably actively repressing plant defense. The only fungal gene found was induced 37 dpi and encodes UDP-glucose pyrophosphorylase, an enzyme involved in the biosynthesis of trehalose. Trehalose biosynthesis was probably induced in response to prior activation of plant antifungal genes and may act as an osmoprotectant against membrane damage.

Protocolo para la inoculación artificial de plantas de Musa spp. con Mycosphaerella fijiensis y evaluación de su respuesta mediante variables epifitiológicas y componentes de la resistencia

Abstract: The use of assessment methods of Musa response to natural infection with M. fijiensis in field has allowed differentiation of susceptible, partially resistant and resistant genotypes to black Sigatoka. However, artificial inoculation methods are not reproducible. Neither, characterization of the infective cycle of M. fijiensis combined with the use of epidemiological variables and components of resistance to differentiate genotypes of Musa spp has been achieved. A protocol to solve this problem is presented in this paper. It describes aspects related to cultural characteristics, morphological, molecular and aggressiveness of isolates of M. fijiensis , and the use of descriptive evaluation scale. It also allows the use of epidemiological variables and components of resistance to characterize the infective cycle of M. fijiensis in greenhouse and differentiate the response of susceptible and resistant genotypes. This protocol is able to reduce the time required to evaluate the resistance of Musa spp against M. fijiensis and therefore to make a greater number of evaluations. It also provides a tool for supporting related studies on Musa-M. fijiensis interaction, facilitates the validation of bioinformatic predictions, opens a path in search of new candidates of fungicides and biological control of black Sigatoka. Key words: ascomycetes, genetic improvement, infective cycle

Micobiota epifítica y contaminantes fungosos del establecimiento in vitro de la guayaba (Psidium guajava L)

Abstract: The studying of contaminats micobiote on guajaba ( Psidium guajava L.) could help for creating schedule treatment of donator plants and its explants to eliminate or prevent the fungi contamination during guajaba micropropagation. The present work were focused on: qualitative evaluation of epiphytic micobiote from explants of Enana Roja cubana EEA 18-40 plants (treated and not treated with fungicide), to isolate, characterize and identify the filamentous fungi from in vitro establishment of nodal segments. For the filamentous identification was used the wet chamber method and preparations were observed in optic microscopic. PDA Petri dishes were used to cultivate the filamentous fungi at 28oC and dark during 7 to 14 days. The cultural and morphological characteristics were used to identifying each isolate. Nine filamentous fungi genera were identify on donator plants without any fungicide application, the principal genera’s were: Alternaria , Aspergillus , Cladosporium , Colletotrichum , Curvularia , Fusarium , Nigrospora , Penicillium and Trichoderma . The application of Mancozeb 80 PH (7.5g.l -1 ) and Benomyl 50 PH (4g.l -1 ) was not effective on epiphytic contaminants micobiote elimination. All these genera’s with the exception of Nigrospora were detected during the establishment of nodal segments. However the disinfection with hypochlorite at 3% for 10 minutes and HgCl 2 solution at 0.05% and 0.1% could reduced the 50% of al contaminates genera’s. Key words: micropropagation, microbiote contamination, filamentous fungi, surface dessinfectants.

Plantain (Musa spp. cv. 'Navolean' AAB) transgenic plants from Agrobacterium tumefaciens-mediated transformation of embryogenic cell suspensions

Abstract: El presente trabajo fue realizado con el objetivo de obtener plantas transgenicas de platano cultivar ‘Navolean’ (Musa AAB) y evaluar estas bajo condiciones de campo durante el primer ciclo de cultivo para la enfermedad Sigatoka negra Suspensiones celulares embriogenicas obtenidas desde domos meristematicos fueron usadas para la transformacion por Agrobacterium tumefaciens La cepa de bacteria EHA-105 fue utilizada con el plasmido binario pHGA-91, el cual contenia combinaciones de los genes que codifican para las antifungicas enzimas glucanasa y la osmotina ap24 Veinticuatro putativas lineas transformadas fueron obtenidas despues de dos meses de seleccion en medio de cultivo Lo eventos transgenicos fueron verificados por la via de PCR e hibridacion Southern y estos confirmaron la integracion estable y expresion del transgen en las plantas transgenicas que fueron seleccionadas en el campo y que mostraron diferencias con las plantas no transgenicas usadas como control

A green fluorescent protein-transformed Mycosphaerella fijiensis strain shows increased aggressiveness on banana

Abstract: The fungal pathogen Mycosphaerella fijiensis, causal agent of black leaf streak disease of bananas and plantains, was transformed with a green fluorescent protein-carrying construct by using a restriction enzyme-mediated integration methodology. A quantitative polymerase chain reaction was adapted to estimate transgene copy number and pathogenicity assays with three banana genotypes with dissimilar reactions to M. fijiensis infection were performed to characterize the transformants. Transgene insertion varied from one to five copies per genome among four random selected transformants. All M. fijiensis strains produced typical symptoms of the black leaf streak disease on the three banana genotypes assayed. Interestingly, the GFP-18 transformant showed increased aggressiveness on susceptible ‘Grande naine’ and resistant ‘Yangambi km5’ plants demonstrating that mutation events in M. fijiensis can increase virulence.

Biotechnological advances in guava ( Psidium guajava L.): recent developments and prospects for further research

Abstract: Guava (Psidium guajava L.), an important fruit crop of several tropical and sub-tropical countries, is facing several agronomic and horticultural problems such as susceptibility to many pathogens, particularly guava wilting caused by Fusarium oxysporium psidii, low fruit growth, short shelf life of fruits, high seed content, and stress sensitivity. Conventional breeding techniques have limited scope in improvement of guava owing to long juvenile period, self incompatibility, and heterozygous nature. Conventional propagation methods, i.e., cutting, grafting or stool layering, for improvement of guava already exist, but the long juvenile period has made them time consuming and cumbersome. Several biotechnological approaches such as genetic transformation may be effective practical solutions for such problems and improvement of guava. The improvement of fruit trees through genetic transformation requires an efficient regeneration system. During the past 2–3 decades, different approaches have been made for in vitro propagation of guava. An overview on the in vitro regeneration of guava via organogenesis, somatic embryogenesis, and synthetic seeds is presented. Organogenesis in several different genotypes through various explant selection from mature tree and seedling plants has been achieved. Factors affecting somatic embryogenesis in guava have been reviewed. Production of synthetic seeds using embryogenic propagules, i.e., somatic embryos and non-embryogenic vegetative propagules, i.e., shoot tips and nodal segments have also been achieved. Development of synthetic seed in guava may be applicable for propagation, short-term storage, and germplasm exchange, and distribution. An initial attempt for genetic transformation has also been reported. The purpose of this review is to focus upon the current information on in vitro propagation and biotechnological advances made in guava.

Hydrogen Peroxide in Plants:a Versatile Molecule of the Reactive Oxygen Species Network

Abstract: Plants often face the challenge of severe environmental conditions,which include various biotic and abiotic stresses that exert adverse effects on plant growth and development. During evolution,plants have evolved complex regulatory mechanisms to adapt to various environmental stressors. One of the consequences of stress is an increase in the cellular concentration of reactive oxygen species(ROS),which are subsequently converted to hydrogen peroxide(H2O2). Even under normal conditions,higher plants produce ROS during metabolic processes. Excess concentrations of ROS result in oxidative damage to or the apoptotic death of cells. Development of an antioxidant defense system in plants protects them against oxidative stress damage. These ROS and,more particularly,H2O2,play versatile roles in normal plant physiological processes and in resistance to stresses. Recently,H2O2 has been regarded as a signaling molecule and regulator of the expression of some genes in cells. This review describes various aspects of H2O2 function,generation and scavenging,gene regulation and cross-links with other physiological molecules during plant growth,development and resistance responses.

De Novo characterization of the banana root transcriptome and analysis of gene expression under Fusarium oxysporum f. sp. Cubense tropical race 4 infection

Abstract: Bananas and plantains (Musa spp.) are among the most important crops in the world due to their nutritional and export value. However, banana production has been devastated by fungal infestations caused by Fusarium oxysporum f. sp. cubense (Foc), which cannot be effectively prevented or controlled. Since there is very little known about the molecular mechanism of Foc infections; therefore, we aimed to investigate the transcriptional changes induced by Foc in banana roots. We generated a cDNA library from total RNA isolated from banana roots infected with Foc Tropical Race 4 (Foc TR 4) at days 0, 2, 4, and 6. We generated over 26 million high-quality reads from the cDNA library using deep sequencing and assembled 25,158 distinct gene sequences by de novo assembly and gap-filling. The average distinct gene sequence length was 1,439 base pairs. A total of 21,622 (85.94%) unique sequences were annotated and 11,611 were assigned to specific metabolic pathways using the Kyoto Encyclopedia of Genes and Genomes database. We used digital gene expression (DGE) profiling to investigate the transcriptional changes in the banana root upon Foc TR4 infection. The expression of genes in the Phenylalanine metabolism, phenylpropanoid biosynthesis and alpha-linolenic acid metabolism pathways was affected by Foc TR4 infection. The combination of RNA-Seq and DGE analysis provides a powerful method for analyzing the banana root transcriptome and investigating the transcriptional changes during the response of banana genes to Foc TR4 infection. The assembled banana transcriptome provides an important resource for future investigations about the banana crop as well as the diseases that plague this valuable staple food.