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Protecting plants against fundamentally radical pathogens is one of arbuscular mycorrhizal fungi's benefits. This work was aimed at comparing the effect of one such fungus (Glomus mosseae) on inducing a defensive response in two rice (Oryza sativa) varieties (LP-7 and J-104). Peroxidise, polyphenoloxidase, chitinase, (3-1,3 glucanase and phenylalanine ammonium lyase enzymatic activity and peroxidase and polyphenoloxidase isoenzymatic expression were determined in both radical and foliar tissues. Mycorrhizal colonisation and visual density percentage were also evaluated. The results revealed that the G. mosseae fungus caused variations in enzymatic activity. Differences were observed in the two varieties behaviour patterns according to evaluation time and plant área studied. The differences detected in peroxidase and polyphenoloxidase electrophoretic patterns were due to the varieties and not to mycorrhisation effect. Rice variety LP-7 generally presented a successful response to inoculation with the G. mosseae arbuscular mycorrhizal fungus, manifesting higher defence mechanism induction. The best results for protecting crops could thus be obtained by using this combination. Key words: peroxidase, polyphenoloxidase, chitinase, (3-1,3 glucanase and phenylalanine ammonium lyase.Entre los beneficios que los hongos micorrízicos arbusculares proporcionan a las plantas se encuentra la protección contra patógenos, fundamentalmente radicales. Por lo que fue objetivo de este trabajo comparar el efecto de uno de estos hongos, Glomus mosseae, en la inducción de respuestas de defensa en dos variedades de arroz (Oryza sativa), LP-7 y J-104. Para lo cual se determinaron, tanto en tejido radical como foliar, las activida­des enzimáticas de peroxidasa, polifenoloxidasa, quitinasa, (3-1,3 glucanasa y fenilalanina amonio liasa; así como la expresión isoenzimática de peroxidasas y polifenoloxidasas. También se evaluaron los porcentajes de colonización micorrízica y densidad visual. Los resultados revelaron que el hongo G. mosseae provocó varia­ciones en las actividades enzimáticas evaluadas, donde se observaron diferencias en el comportamiento entre las variedades según el tiempo de evaluación y el área de la planta estudiada. Las diferencias detectadas en los patrones electroforéticos de peroxidasas y polifenoloxidasas se deben a las variedades y no al efecto de la micorrización. En general, la variedad de arroz LP-7 mostró una respuesta satisfactoria a la inoculación con el hongo micorrízico arbuscular G. mosseae, manifestando una mayor inducción de mecanismos defensivos, por lo que pudieran alcanzarse los mejores resultados aplicando esta combinación en cuanto a protección del cultivo. Palabras clave: peroxidasa, polifenoloxidasa, quitinasa, (3-1,3 glucanasa y fenilalanina amonio liasa.

The aim of this study was to determine the molecular variability in a collection of Venezuelan isolates of entomopathogenic nematodes and their symbiont bacteria through the application of RAPD markers. The DNA of nematodes and bacteria were extracted by a modification of the method described by Salazar et al. RAPD assay was developed with the primers from the kits OPA and OPB. Genetic fingerprinting of isolates of the nematode and symbiotic bacteria were determined. The total amplified bands for nematode was 493 and 496 for bacteria, with 99,18 and 100% polymorphism, respectively. The clustering obtained for the nematodes was related to the altitude above the sea level at which they were collected, while for the bacteria, the clustering was in general related to the type of soil from which they came. [ABSTRACT FROM AUTHOR]

Food production worldwide is among the priorities of governments and institutions. The overall strategy for improving crop yields with less environmental impact, reduction of chemical application and preservation of biodiversity is geared towards sustainable agriculture. Resistant varieties are a tactic widely used in integrated pest management; thus breeding programs are a priority for achieving this goal. Understanding of the pathogens and the physiological bases, and the molecular and genetic interactions governing the plants may contribute to achieve durable resistance. In this complex scenario, a group of research works studying the interactions between hybrid Saccharum spp., Solanum lycopersicum L., Oryza sativa L., and different pathogens was developed at the National Center for Agricultural Health (CENSA), for over 25 years. The results are reported in this paper. [ABSTRACT FROM AUTHOR]

Beauveria bassiana (Balsamo) Vuillemin is a promisoring biological control agent for invertebrate pests. In the development of a product based on a biological control agent, the study of the mode of action and the metabolites involved and their expression by the promissory strains is needed for selection, mass rearing, formulation and strain identity. The aim of this work was the biochemical characterization of six B. bassiana isolates by a time course experiment in different culture media. Mycelia disk of six B bassiana isolates were grown in a basal medium as the control, basal medium supplemented with chitin and basal medium supplemented with gelatine. Total proteins, chitinase and glucanase activities were assayed at 3, 5 and 7 days post inoculation. In general, isolates 33 and 9 showed the highest levels for all the parameters studied. The medium supplemented with chitin was the best for total protein and chitinase activity expression, while the media supplemented with gelatine was the best for glucanase production. [ABSTRACT FROM AUTHOR]

The leaf mold caused by Cladosporium fulvum Cooke, is a very common and destructive disease in the tomato crop. Although there are cultivars with one or more resistance genes, the fact that the fungus has a very high mutation level, results in a limited use of such materials. For that reason, the knowledge of the pathogen populations contributes to the breeding program efforts to develop strategies to extent the useful life of the materials obtained. The objective of this work was the molecular characterization of the variability in a group of C. fulvum isolates from tomato plants. The molecular characterization was carried out for 37 isolates, including identification by the 28S region encoding for RNAr amplification, PCR with specific primers directed to different genes related to pathogenicity (Avr2, Avr4, Avr4E, Avr9, Ecp1, Ecp2, Ecp4 y Ecp5) and RAPDs. All the isolates were classified as C. fulvum. Any of them amplified for the Avr9 gene, although there were high amplification percentages for the Avr2, Avr4 and Avr4E genes. The virulence of the races 2, 4, and 2.4 were more related to the presence of the Ecp2 protein (100%) than to Ecp1. All the markers used confirmed a high level of molecular variability, although no relation the geographical origin was found. [ABSTRACT FROM AUTHOR]

The introduction of varieties resistant to phytopatogens is one of the most used alternatives at present. The availability of a broad genetic variability is very important for the success of an improvement program. The molecular markers are powerful tools to study the genetic diversity characterization. The aim of this work was to know the genetic variability among six promissory tomato genotypes obtained in breeding programs for TYLCV resistance by means of RAPDs. Scarce genetic variability among studied genotypes was observed in the results. [ABSTRACT FROM AUTHOR]

The article presents a study which discussed real-time polymerase chain reaction (PCR) to monitor and assess the effectiveness of the inoculum of the nematophagous fungus Pochonia chlamydosporia variety catenulata against root-knot nematode populations. The results taken from the real time PCR and colonies former units were correlated. d

There are at least six species of Phytophthora reported as causative agents of cacao disease known as black pod, which causes great losses worldwide. In order to identify and characterize the main species of Phytophthora present in cacao crop at Baracoa, Guantanamo, 90 isolates extracted from diseased fruits of cocoa were tested by pairing with the reference strains of Phytophthora palmivora 52539 (A1) and 52540 (A2), from the fungal collection of the Catholic University of Louvain, Belgium. Of the total isolates tested, 88 were consistent with the type A1 strain. The two remaining isolates showed no compatibility with either of the two reference strains, indicating the presence of another species. [ABSTRACT FROM AUTHOR]

Los agentes de control biológico se han convertido en importante alternativa al uso de los químicos contra las plagas, lo cual impone nuevos retos a la investigación. En el desarrollo de un producto basado en un agente de control biológico como componente activo, es necesario tener en cuenta una serie de pasos que van desde la prospección y selección hasta el registro. En la actualidad, en algunas de estas fases de la investigacióndesarrollo es vital contar con herramientas que permitan comprobar identidad, pureza, calidad y destino ambiental del agente liberado. Aun cuando existen técnicas convencionales para cubrir algunas de estas necesidades, en algunos, estas resultan insuficientes; no obstante, la Biología Molecular puede asistir a los investigadores en el estudio de la identidad, diversidad, selección de candidatos apropiados para el control biológico y apoyar las pruebas de control de calidad. El objetivo de este trabajo fue la aplicación de diferentes técnicas moleculares en la investigación de agentes de control biológico promisorios, desarrollados en Cuba. Para ello se expondrán, como casos de estudio, tres ejemplos: nematodos entomopatógenos (Heterorhabditis sp. y su bacteria simbionte Photorhabdus luminescens), Trichoderma sp. y Pochonia chlamydosporia. A partir de muestras de estos agentes de control biológico se realizaron extracciones de proteínas totales y ADN, las cuales fueron analizadas por las técnicas para la determinación de proteínas totales, actividades enzimáticas específicas, PCR-ITS, PCR-EF, secuenciación de ácidos nucleicos, PCR en tiempo real, AFLP, RAPD. Se muestran los resultados obtenidos con relación a la identificación certera, los modos de acción, el control de la calidad y el monitoreo de los agentes estudiados. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the potential of strains of Trichoderma asperellum, Lieckfeldt & Nirenberg to control M. incognita, (Kofoid and White) Chitwood. Under laboratory conditions (in vitro), six native strains of T. asperellum (Ta.25, Ta.1, Ta.90, Ta.78, Ta.79, and T.13) were selected for their high antagonistic capability, production of various metabolites, and adaptation to different environmental conditions and substrates. For the in vitro trial, 1/10, 1/25, 1/50 dilutions and the pure filtrate of each strain were tested, including a control treatment with sterile water. For the study under semi-controlled conditions, tomato (Solanum lycopersicum L.) plants were inoculated with 2.5 second instar juveniles (J) per gram of soil and, after 72 hours, 107CFU of the strain Ta.90 were added per pot The treatments were: healthy plants (absolute control), plants + Ta.90, plants +Ta.90 + nematodes, plants + nematodes, and nematodes + Ta.90 (without plants). The parameters evaluated after 35 days were galling index (IA), number of eggs per root system, plant height, stem diameter, root length, number of leaves, and weight of fresh root. High mortality levels were shown by all the T. asperellum strain filtrates; the strain Ta.90 stood out with 90% mortality at 24 hours. In the pot trial, this latter strain significantly reduced the number of eggs per female compared with the unapplied control, and attenuated the effect of the nematode on parameters such as plant height, stem diameter, number of leaves, and root fresh weight. [ABSTRACT FROM AUTHOR]

Disease caused by Rhizoctonia solani Kühn infestations has become a growing problem for commercially important crops. Although this fungus is usually controlled through the application of chemicals, the heavy ecological and financial toll of the latter has prompted for research on biopesticides as a viable alternative. Trichoderma spp. is a well-known fungus often used for the biological control of crop pests, whose anti-fungal mechanisms include competition for the substrate, antibiosis and/or mycoparasitism. In the present work, we have used molecular techniques (sequencing of amplicons from the internal transcribed spacer of ribosomal DNA and the EF1A translation elongation factor) for the taxonomic identification of 13 Trichoderma spp. isolates in our collection, also evaluating their antibiotic effect on strains from three anastomosis groups of R. solani (AG-2.1, AG-5, AG-8) by the cellophane method. The sequences obtained from all isolates exhibited 100 % identity with deposited T. asperellum Samuels sequences in TrichoBLAST/GenBank, enabling their taxonomic assignment to this species. When analyzed by in vitro tests, over 70 % of the isolates exhibited a fungistatic effect towards R. solani, with the remaining strains exhibiting fungicidal activity; these results were later corroborated by technical efficacy tests under field conditions. Isolates 3, 13, 17, 75, 78, 85 and 90 were selected as potential biocontrol agents due to their high antibiotic activity and technical efficacy under field conditions. [ABSTRACT FROM AUTHOR]

The incidence of diseases caused by Rhizoctonia solani Kühn increases every year. Control of this disease is mainly done with the application of chemicals, more highly toxic. For this reason it is necessary to apply new control alternatives Trichoderma spp. is one of the biological control of this pathogen, for the friendly behavior and the different mechanisms of action, such as competition for the substrate, antibiosis and/or mycoparasitism. The present work had as objectives the molecular identification and the pathogenic evaluation, against R. solani isolates, of 13 isolates of the genus Trichoderma. For this, the antibiotic effect of Trichoderma asperellum on three R. solani anastomosis groups (AG-2.1, AG-5, AG-8) was evaluated by the method of cellophane. The characterization was carried out by sequencing the Internal Transcribed Spacer (ITS) of the rDNA region, as well as the EF1A translation elongation factor. Over 70 % of the strains tested showed fungistatic effect, whereas the rest showed fungicide effect. This was corroborated by the technical effectiveness under field conditions. After sequencing and comparison of data obtained with other sequences deposited in TrichoBLAST/GenBank, we found that all isolates showed 100 % identity with the T. asperellum Samuels species. Isolates 3, 13, 17, 75, 78, 85 and 90 were selected as promissory for their high antibiotic potential and technical efficacy in field conditions. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum f. sp. lycopersici (Sacc.) Snyder and Hansen is the causal agent of the vascular wilt in tomato. The use of resistant varieties is one of the most effective methods for managing this disease. This paper summarizes the biochemical and molecular mechanisms mediating the natural and induced resistance to Fusarium oxysporum f. sp. lycopersici-tomato interaction. [ABSTRACT FROM AUTHOR]

Three protocols were tested to evaluate the efficiency of the genomic DNA extraction from insects of the Order Thysanoptera. Ethanol preserved adults of the Genera Frankiniella Karny and Thrips Linneaus were used as the material for the extraction. The efficiency was measured through the amplification of the ITS region in a multiplex PCR assay using the primers ITS1, ITS2, CS249 and CS250. The PCR product was separated by electrophoresis on 1% agarose gel. It was demonstrated that no amplification was obtained following the protocol of Aljanabi and Martínez, whereas the protocols described by Rugman and Moritz showed well defined band patterns, suggesting that both procedures can be used for the DNA extractions. [ABSTRACT FROM AUTHOR]

Trichoderma species fungi secret hydrolytic enzymes which allow them to penetrate the cell walls of phytopathogenic fungi. The glucanases are enzymes that hydrolyze the (3-glucans of the cell wall of phytopathogens such as Sclerotium rolfsii, Rhizoctonia solani and Pythium sp. The aim of this work was to carry out the dynamics of glucanase induction of ten Trichoderma spp. isolates evaluating the enzymatic activities at the first, third, fifth and seventh days of the cultures in three liquid media: basal medium, basal medium supplemented with chitin 0,5% and basal medium supplemented with gelatine 0,2%. The isolates 1, 13 y 17 reached the highest levels of glucanase specific activity during the induction with the basal medium supplemented with gelatine. The basal medium also resulted to be a good inductor of those enzymes. [ABSTRACT FROM AUTHOR]

Ralstonia solanacearum (Smith) Yabuuchi is the causal agent of bacterial wilt. This disease affects some important crops such as: tomato, potato, tobacco, banana, eggplant and some ornamental crops specially in tropical and subtropical areas. It has been very difficult to control the disease due to its wide host range, distribution and high variability. In this paper, the bacterial pathogenecity mechanisms as well as the molecular ones for the natural and induced resistance in plants are exposed. [ABSTRACT FROM AUTHOR]

The endophytic and stimulating effect of four strains of Trichoderma asperellum Samuels, Lieckfeldt & Nirenberg (Ta. 13, Ta. 78, Ta. 85, and Ta. 90) on Phaseolus vulgaris (Cv. BAT-304) was evaluated under semi-controlled conditions. The number of leaves and roots, plant height, root length, fresh foliar and root mass, dry foliar and root mass, endophytic capacity in roots, foliar content of N, P, K and the induction of peroxidase enzymes (POD), polyphenoloxidases (PPO), and phenylalanine ammonium lyases (PAL) were determined. The evaluations were carried out in 15-day old plants sown at two times:1) plant sowing and soil inoculation with Trichoderma at the same time, 2) planting seven days after soil inoculation with the fungus). The strain Ta. 85 produced the greatest stimulation in terms of number of leaves, plant height and root length with the first time of sowing. All the strains were endophytic for the bean cultivar studied. Ta. 90 and Ta.85 increased the leaf content of N with the first sowing time, whereas Ta. 78, Ta. 85, and Ta. 90 did it with the second sowing time. Only Ta. 78 increased the leaf K with respect to the control with the second sowing time. The plants treated with Ta. 78 showed higher POD, PPO and PAL enzymatic activities with respect to the control plants. Ta. 13 increased POD and PPO activities, whereas Ta. 85 and Ta. 90 only the PPO activity. The results suggest that strain Ta. 85 inoculated at bean planting is efficient in stimulating growth, whereas Ta. 78 stood out in nutrition and induction of possible resistance in this crop. [ABSTRACT FROM AUTHOR]

El desarrollo de productos comerciales, a partir de hongos para el control de plagas que afectan cultivos de importancia económica, adquiere una importancia relevante como alternativa ambientalmente segura para el manejo de plagas en los programas de producción diversificada de alimentos y la reducción de plaguicidas químicos. El CENSA tiene implementada una tecnología de Fermentación en Estado Sólido en Bolsas (FESB) de bajos insumos que asegura una calidad elevada de los productos y es asimilable para la producción masiva de hongos mitospóricos. El objetivo del presente trabajo fue la evaluación de esta tecnología para la obtención de un nuevo producto para uso en la agricultura, a partir de la cepa nativa cubana seleccionada Vl-01 de Lecanicillium lecanii (ex. Verticillium lecanii). Se realizaron, además, estudios de caracterización desde los puntos de vista biológico y patogénico frente a diferentes dianas, y se evaluó la producción in vitro de enzimas hidrolíticas (quitinasas y glucanasas) que juegan un papel importante en el mecanismo de acción y la patogenicidad de la cepa. La producción de conidios por FESB estuvo entre 2x108 y 1,6x109 conidios.g-1 de sustrato colonizado, con viabilidad media de 80%. La máxima esporulación ocurrió a 28ºC a los 15 días de incubación. Los resultados muestran las potencialidades de uso de la cepa como nuevo producto y avalan la continuidad de los estudios para su uso en la agricultura. [ABSTRACT FROM AUTHOR]

In this work, the induction of chitinases and β-1,3-glucanases was evaluated in the strain Vl-01 of Lecanicillyum lecanii (Zimm.) Zare & W. Gams in three culture media with different inductors: basal medium, basal medium supplemented with 0,5% of chitin, and basal medium supplemented with 0,2% of gelatin. The enzymatic activities were determined at 24, 72, 120, and 168 hours. The higher enzymatic levels of both chitinases and glucanases were obtained in the basal medium supplemented with gelatin. [ABSTRACT FROM AUTHOR]

In this work, the effect of different essential oils was evaluated using tomato cv. Amalia plants. The plants were sprayed with different oils and inductors as Bion, and leave samples were taken at 24, 72 and 144 hours after spray. Total protein concentration and specific enzymatic activities of peroxidases, polyphenoloxidases, phenylalanine ammonia lyase and chitinases were determined. The essential oils obtained from citric fruit scraps and Melaleuca quinquenervia (Cav) S.T. Blake induced higher peroxidases, polyphenoloxidases and chitinases enzymatic activities. Jasmonic acid and phospholipids were responsible for phenylalanine ammonia lyase induction. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented regarding the use of essential oils as a defense response in tomato plants.

The experiment was carried out under semi controlled conditions in biological insulators (18-21°C), with the objective of determining the duration of the life cycle of Meloidogyne incognita (Kofoid & White) Chitwood and the egg production of the adult females on tomato (Solanum lycopersicum L.) in the first 96h. Plants with about 15cm of height were transplanted to pots and, a week later, inoculated with 2500 ±5 J2 of M. incognita race 2. At 72 hours, they were removed and planted in pots with sterile soil. The root system was drawn out six days after inoculation to observe the different stages. The average temperature during the study was 18 to 21°C. Three plants were removed and the daily extraction was stopped 96 h after the first adult females with eggs in the gelatinous matrix were observed. Between 7 and 10 days after inoculation, the roots of tomato showed swollen areas, indicative of the entrance of the juveniles and their feeding. The life cycle from J2 to female eggs with gelatinous matrix was 24 days. In the first 24 hours, the females deposited over 50 eggs in the wombs, and at 96h, each of them had an average of eggs higher than 100. [ABSTRACT FROM AUTHOR]

The resistance/susceptibility of Solanum lycopersicum L genotypes Aro 8484, HA 3063, Caramba and HA 8476 against Meloidogyne incognita Kofoid and White (Chitwood) race 2 and the influence of the nematode on the genotype growths were evaluated in two experiments under semi-controlled conditions. In the first experiment, the genotypes, including a susceptible control tomato Campbell-28, were inoculated with a level of 1,5 J2. g of soil-1. Root gall index, was reproduction factor and reproduction index of the nematode were determined for categorizing resistant/susceptible genotypes. In the second experiment, three levels of nematodes (0,5; 1,5 and 2,5 J2. g of soil-1) were used. Not inoculated genotypes were established as a control. Both experiments had 10 repetitions and were placed in a green house using a randomized distribution design. A lineal regression analysis was used to establish the relation of nematode levels and the plant growths. All genotypes were susceptible to M. incognita. It was demonstrated that the 60 to 94% of plant growth decrease related to the nematode population increase. The use of genotypes is not recommended in soils infected with M. incognita unless management measures are established for keeping nematode population below 0,5 J2.g of soil-1. [ABSTRACT FROM AUTHOR]

Use of fungi of the Trichoderma genus for the biological control of pests and diseases is based, to a large extent, on their secretion of hydrolytic enzymes. The latter include chitinases and glucanases, which degrade the cell wall of phytopathogenic fungi as well as the cuticle of insects and nematodes. The aim of this study was to assess the induction dynamics of chitinases and glucanases in ten strains of Trichoderma spp. grown in liquid media with different inducers: basal medium, basal medium supplemented with 0.5% chitin and basal medium supplemented with 0.2% gelatin. Chitinase and glucanase activity were evaluated at the first, third, fifth and seventh day of culture. The highest values of chitinase activity were obtained in basal and basal media supplemented with chitin; β-1.3-glucanase, on the other hand, exhibited higher levels of activity in basal and basal media supplemented with gelatin. [ABSTRACT FROM AUTHOR]

Use of fungi of the Trichoderma genus for the biological control of pests and diseases is based, to a large extent, on their secretion of hydrolytic enzymes. The latter include chitinases and glucanases, which degrade the cell wall of phytopathogenic fungi as well as the cuticle of insects and nematodes. The aim of this study was to assess the induction dynamics of chitinases and glucanases in ten strains of Trichoderma spp. grown in liquid media with different inducers: basal medium, basal medium supplemented with 0.5% chitin and basal medium supplemented with 0.2% gelatin. Chitinase and glucanase activity were evaluated at the first, third, fifth and seventh day of culture. The highest values of chitinase activity were obtained in basal and basal media supplemented with chitin; β-1.3-glucanase, on the other hand, exhibited higher levels of activity in basal and basal media supplemented with gelatin. [ABSTRACT FROM AUTHOR]

Essential oils stand out as rapidly developing products and many applications in agriculture. Melaleuca quinquenervia (Cav) S.T. Blake, essential oil producer specie of the Myrtaceae family, has medicinal and insecticide properties, but its possibilities to be used in the control of pests in different crops are very important and must be further investigated. The aim of this work was to determine the chemical composition of M. quinquenervia essential oil and its acaricide and antimicrobial activity against agricultural pests. The essential oil was obtained by hydrodistillation using a Clevenger type-apparatus and the yield was determined. The chemical composition was investigated by GC/MS. Biological tests were conducted against fungi, bacteria and mites. The essential oil of M quinquenervia (yield: 2,97% (v / p)) is mainly composed of longifolene (32,95 %), 1.8-cineole (25,43 %), viridiflorol (7,76 %) and allo-aromadendrene (9,50 %). The essence has a promising antifungal effect against Alternaria solani Sor. and Fusarium sp.. The susceptibility of isolates of the latter plant pathogen showed differences with the greatest inhibition produced by F2. Xanthomonas albilineans (Ashby) Dawson was the most sensitive bacteria to the action of the oil, compared with Clavibacter michiganesis subsp. michiganesis (Smith) Davis et al showed only a slight activity at the highest dose tested. The antibacterial effect against X. albilineans was superior to that produced by the control antibiotic. The essential oil was highly toxic to mite causing 100% of mortality against females of Tetranychus urticae Koch, Panonychus citri (McGregor) and Raoiella indica Hirst, and 88,73 % on Tetranychus tumidus Banks. The essential oil of Melaleuca quinquenervia has potential for the development of new antimicrobials and acaricides to control pests in vegetables, citrus and sugar cane. [ABSTRACT FROM AUTHOR]

A 21 year old vineyard (Vitis vinifera L. cv. Aramond) showed symptoms similar to those caused by the root knot nematodes (Meloidogyne spp.) as well as decreases in yield. In a visit to the area, several chlorotic plants with different degree of defoliation were observed. The stem bases above the soil surface were swollen and they showed longitudinal cracks. Galls of different sizes were observed on the roots with significant losses of secondary roots. Adult females of Meloidogyne with well developed egg masses were found inside the galls. The study of the perineal patterns of these females showed the presence of specimens belonging to three species (Meloidogyne arenaria (Neal) Chitwood, Meloidogoyne incognita (Kofoid & White) Chitwood and Meloidogyne javanica (Trueb) Chitwood), as well as others that were grouped as Meloidogyne spp. until completing the molecular studies of all the specimens observed. M. arenaria showed to be the majority component of the community with 53%, followed by M. incognita and M. javanica with 21% and 4% respectively. The presence of M. arenaria in grapevine is the first report of this specie in the crop in Cuba and constitutes a focus of attention for the plant protection service because it is one of the most important pests in grapevine in the world. [ABSTRACT FROM AUTHOR]

Genetic improvement programs are an alternative to obtain pepper genotypes resistant to several diseases. The wide genetic variability of these genotypes makes them promissory for the control of Potato virus Y (PVY). The RAPD markers are a useful tool to characterize the genetic diversity of pepper varieties. The aim of this work was to evaluate the genetic variability of pepper genotypes obtained in the breeding program for PVY resistance using RAPD markers. In general, the results showed a low variability between the genotypes studied. [ABSTRACT FROM AUTHOR]

Tomato is one of the most important crops of the world. The tomato yellow leaf curl virus (TYLCV) is one of the most aggressive pathogen to this vegetable. The resistant varieties for the TYLCV control depend on the availability of promissory genotypes. The isoenzymes have been used to investigate the aspects related to the host resistance and the pathogens effect on host metabolism at a biochemical level. The aim of this work was to characterize six promissory tomato genotypes obtained in breeding programs for TYLCV resistance by means of enzymatic activities and phenolyc compound determination. The results showed that the 3 genotypes could be the most promissory for these purposes. [ABSTRACT FROM AUTHOR]

The root knot nematodes (Meloidogyne spp.) are limiting factors for yields of vegetables in open areas and crops under shelter conditions, where tomato Solanum lycopersicon L. (ex Lycopersicon esculentum Mill.) represents a very good host for these nematodes. For population management of this pest, resistance and graffing are used, among other tactics, to obtain good productive results, but it is necessary to evaluated the resistance of genotypes to native populations, since as it is know resistance may be broken by factors like virulence of Meloidogyne population. The objective of this study was to determine the behaviour of tomato lines hybrids and varieties to native population of M. incognita race 2, as a basic element for the graffting program being develop in Cuba as an alternative to methyl bromide. Ten plants per genotype were inoculated with 1,5 eggs/juvenils.g of soil-1 and evaluated after 60 days to determined the Root Galling Index (IA), the Reproduction Factor (FR) and the Reproduction Index (IR). The cultivars evaluated were Lycopersicon peruvianum acc. B6-140; Physalis ixocarpa acc. B6236; Lycopersicon pimpinellifolium acc. Mex 121-A; the following varieties/hybrids of Solanum lycopersicum var. ceraciforme, Vyta, Mariela, Amalia, HC 3880 and HA 3019; the interespecific hybrid Lycopersicon hirsutum x L. esculentum, Solanum torvum and the tomato hybrids T-1x14, T-1x15, T-2x16 and LTM. The interespecific hybrid L. hirsutum x L. esculentum was immune, whereas S. torvum and L. peruvianum were very resistant. In other hand, P. ixocarpa behaved as moderately resistant and the rest of genotypes were susceptibles to the Cuban population of M. incognita race 2. [ABSTRACT FROM AUTHOR]

In this paper, general aspects of the interaction tomato-Meloidogyne incognita are summarized. The morphological and physiological specifications of nematodes as organisms causing diseases, the mechanisms developed by this group during penetration and infectation and the plant defense mechanisms are analized. [ABSTRACT FROM AUTHOR]

Los recursos genéticos contribuyen al desarrollo sostenible y constituyen la materia prima que permitirá hacer frente a diferentes estreses como son las plagas, las sequías y los cambios climáticos. El maíz (Zea mays L.) ha sido ampliamente estudiado, debido a la importancia que tiene el cultivo como fuente de alimentación básica para muchas personas en todo el mundo. De ahí que resulta de vital necesidad conocer la variabilidad genética del cultivo en función de la conservación de la diversidad existente. Para el presente trabajo nos planteamos como objetivo caracterizar la variabilidad genética del cultivo del maíz en zonas montañosas de Cuba mediante el uso de marcadores RAPD. En el análisis se emplearon 32 accesiones colectadas en diferentes regiones de Pinar del Río y Guantánamo y 5 variedades comerciales. Los resultados corroboraron la variabilidad molecular presente en el cultivo del maíz en nuestro país y la formación de 4 grupos, los cuales tienen mayor relación con el lugar de procedencia de las accesiones analizadas. [ABSTRACT FROM AUTHOR]

Se estudió el efecto de diferentes aceites esenciales en la inducción de mecanismos defensivos en tomate (Solanum lycopersicum L. cv. Amalia). Las plantas se asperjaron con diferentes aceites e inductores como el Bion y se tomaron muestras de las hojas a las 24, 72 y 144 horas posteriores a la aspersión. Se determinó la concentración de proteínas totales, así como la actividad enzimática específica de peroxidasas, polifenoloxidasas, fenilalanina amonio liasas y quitinasas. Los aceites esenciales obtenidos a partir de subproductos de la industria de cítricos y de melaleuca (Melaleuca quinquenervia (Cav) S.T. Blake) indujeron las mayores actividades enzimáticas de peroxidasas, polifenoloxidasas y quitinasas. El ácido jasmónico y los fosfolípidos fueron los responsables de la inducción de fenilalanina amonio liasas. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented on the topic of the genetic diversity of Apis mellifera.

The article discusses a report on the biotransformation methods from which it is possible to obtain several raw materials for industrial processes, most of them applicable to sectors such as pharmaceutical, chemical, food, and agriculture. Particular focus is given to the peroxidases which are useful enzymes that are capable to carry out biotransformation reactions.