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Copyright of Revista Chapingo Serie Horticultura is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The genetically modified common bean (Phaseolus vulgaris L.) cv. Flor de Mayo Anita, with the Arabidopsis thaliana defensin gel (pdf1.2) was characterized by its biological effectiveness and agronomic advantage under confined conditions. Releasing this technology into the environment requires an Environmental Risk Assessment (ERA) in order to identify the possible adverse effects that the suggested use of the recombinant technology may have on the environment when evaluating the probability of risk, its severity, and the biosafety measures recommended to reduce possible risks. The problem formulation was established in the earlier manuscript and it gave rise to three operative protection goals related to the adverse effects on pathogenic organisms and non-target organisms, the increase in the competitive capacity of the common bean-pdf1.2, and the gene flow to conventional bean crops and wild relatives. The final evaluation points were defined, and from there, nine risk hypotheses were outlined. The ERA dismissed the possibility of occurrence of any damages caused by the expression of the defensin or neomycin phosphotransferase II proteins on the non-target microorganisms and the development of resistance on target organisms. Likewise, the possibility of an increase in the competitive capacity of the common bean-pdf1.2 was discarded, since it is a highly dependent agricultural system, and finally, the possibility of an introgression of recombinant sequences into conventional crops or wild relatives was defined as an unlikely risk, due to the absence of coincidences in its phenological stages during its environmental release, along with the genetic barriers among wild relatives. The biosafety measures recommended to minimize the possibility of damage consisted in establishing live bean and maize barriers, the phenological lag between the common bean-pdf1.2 and conventional bean; follow-up studies during release such as the characterization of soil microorganisms before, during and after environmental release, as well as the identification of voluntary plants after the harvest. [ABSTRACT FROM AUTHOR]

The Genetically Modified Organisms Biosafety Law in Mexico indicates the requirement of an Environmental Risk Evaluation (ERE) as part of the requisites that should be in an application for the environmental release of Genetically Modified Organisms (GMOs) in Experimental Stage. The biotechnology model of genetically modified common bean with the defensin gene (pdf1.2) of Arabidopsis thaliana has wide-spectrum tolerance against phytopathogenic fungi, therefore the ERE focused on the possible risks this characteristic could pose to their environmental release. The ERE was carried out in two parts, and this first document focused on the definition of the problem or identifying the hazard based on the characteristics of the common bean-pdf1.2, as well as its receiving environment. The identification of the hazards was framed in the political protection goals for Mexico, established as protection of the environment, of the biological diversity, and plant, animal and aquaculture health; and from these, the operative protection goals derived, related to protecting the non-target organisms, avoiding competitive capacity or as weed-behaviors of the common bean-pdf1.2 plant, limiting the development of the resistance of pathogenic microorganisms and avoiding the gene flow to wild relatives and conventional crops in the experimental agroecosystem. The final evaluation points, defined as the quantitative variables susceptible to some adverse effect were identified as the effect on the diversity of non-target microorganisms, the competitive capacity of the crop, and the development of resistance of target organisms. Finally, risk hypotheses were set forth to identify the risks that the release of the common bean-pdf1.2 could cause in the final evaluation points. These risk hypotheses will be analyzed in terms of characterization and its estimation, as well as ERE biosecurity measures in a second document. [ABSTRACT FROM AUTHOR]

Copyright of Agrociencia is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phytophthora capsici is a phytopathogen that limits the production of vegetables worldwide. It is known to be the causal agent of the wilting of chili pepper, which affects the plantations of the genus Capsicum, causing almost complete losses. The pathosystem Capsicum spp. - P. capsici has been widely studied, but it is still far from being understood. Investigations on different chili pepper cultivars resistant to the oomycete suggest that most genotypes carry defense genes to confront the pathogen; however, the defensive capacity differs in intensity and speed. The specific resistance of some Capsicum species to P. capsici seems to be unrelated to R proteins, but rather mediated by a complex molecular dialogue. In some species of Capsicum, the growth regulators play an important part in this dialogue that leads the plant to express the genes related to defense, locally at first, by limiting the progress of the oomycete, and later, systemically, by preventing new points of infection. This revision carries out a critical analysis of the information available on the communication network established between chili plants and P. capsici, which defines the outcome of the interaction between the plant and P. capsici as resistant, tolerant or susceptible. [ABSTRACT FROM AUTHOR]

Sedentary endoparasitic nematodes introduce into their host, through its stylet, effector molecules that are previously synthesized in their esophageal glands, which induce reprogramming of gene expression in the host cells to promote changes in their metabolism, physiology and structure, necessary for the formation of the specialized feeding sites. The plant responds by expressing defense mechanisms such as the increase in the activity of key enzymes in the phenylpropanoid pathway, involved in the synthesis of secondary metabolites with antimicrobial properties and monomers that make up the lignin, which has a structural and defense roles in plants. The plantnematode interaction established (compatible or incompatible), will depend on whether the changes induced in the lignin synthesis are favorable or not for the differentiation of the specialized feeding site. The aim of this review is to present information on the biosynthesis, composition and deposition of lignin, as well as the updated knowledge on its role as a potential physical barrier against the establishment of phytonematodes in incompatible interactions and their possible participation in the formation of specialized feeding sites in compatible interactions. [ABSTRACT FROM AUTHOR]

Copyright of Agrociencia is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plants of chilli Capsicum annuum L. CM334 show a high level of resistance to Phytophthora capsici, but are susceptible to Nacobbus aberrans; such resistance has been associated with capsidiol accumulation, a sesquiterpene phytoalexin. In the present study the expression of hydroxymethylglutaryl- CoA reductase 2 gene (HMG2, associated with sesquiterpene phytoalexins biosynthesis) in CM334 chilli roots inoculated with N. aberrans and in combination with P. capsici, was determined by qRT-PCR. The levels of HMG2 transcripts were significantly reduced (p⩽0.05) from -1.57 to -1.28- fold in the interaction CM334/N. aberrans; whereas in roots inoculated only with the oomycete, the accumulation of transcripts occurred earlier and at higher levels (1.52 to 3.54-fold). In plants inoculated with both pathogens, the expression was higher compared with those inoculated with the nematode only (p⩽0.05), but generally lower than the expression observed in roots of plants inoculated with the oomycete alone. The expression of the HMG2 gene associated with defense was reduced in CM334 chilli plants infected by N. aberrans. [ABSTRACT FROM AUTHOR]

Copyright of Nematropica is the property of Organization of Nematologists of Tropical America and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Programmed cell death (PCD) or "cellular suicide" occurs in all organisms as a normal process that takes place in an organized and perfectly regulated way, which is essential for the development and survival of the organisms and it is also expressed in response to biotic or abiotic stresses in animals, plants and unicellular organisms. The PCD is a genetically controlled cell death which requires an active participation of the organism and involves a sequence of cellular metabolic events that lead to the destruction of the cell. Currently, based upon the morphological characteristics that the dying cells display and in the kind of cellular organelle involved, three categories of PCD death have been defined: apoptosis, lysosomal death or autophagy ('self-eating'), and nonlysosomal death. The hypersensitive reaction (HR) is considered the maximum expression of plant resistance to pathogen attack and is defined as a fast death of the plant cells associated with the restriction of the pathogen growth, which usually is recognized by the presence of one or several brown-colored dead cells at the infection site. The death of cells that happens during the HR is considered a lysosomal type PCD or autophagy. [ABSTRACT FROM AUTHOR]

The virulence and genetic variation shown by RAPD (Random amplified polymorphic DNA) were determined for 15 monoconidial isolates of Colletotrichum gloeosporioides obtained from leaves and fruits of mango (Mangifera indica) cv. Haden. They were classified into four groups according to their degree of virulence onto inoculated leaves: very virulent (from 19.2 to 9.0% severity, isolates F3, F4, and T5), virulent (from 8.0 to 5.0%, T4, T3, F5, and T1), moderately virulent (from 3.8 to 1.2%, H4, H2, T6, F2, and H3), and scarcely virulent (from 0.1 to 0.01%, H1, F1, and T2). F3 was the most virulent as it showed the highest anthracnose severity. Isolates H4, H1, H2, H3, T6, F2, and T2, showed greater genetic variability and were part of a group that was well separated from F3, F4, and F5. These three were outside the main groups in the dendrogram that was constructed from results of the RAPD analysis. T5 (very virulent) was associated with T3 and T4 (virulent); however, F1 (scarcely virulent) was grouped with F5 (virulent). The results from the RAPD analysis suggest the existence of great genetic variability among the 15 isolates of C. gloeosporioides. [ABSTRACT FROM AUTHOR]

The article reports on the antagonism of Cladosporium sp. against Puccinia horiana Henn. causal agent of white rust of chrysanthemum. It states that the antagonism of Cladosporium sp. isolate RREJSG-04 on Puccinia horiana was evaluated under greenhouse and laboratory conditions. According to the author, the biological efficacy of Cladosporium sp. on P. horiana was 84%. He adds that observations of histopathological sections of pustules colonized by Cladosporium sp. indicated that antagonist acts as an hyper parasite, although other biological mechanisms could be also involved in the antagonism

One of the most important phytosanitary problems in two-year plantations of Agave tequilana var. Azul. is agave wilt, that is caused by several organisms, among those pathogens are reported several species of Fusarium and Thielaviopsis pradoxa. The main goal of this research was to introduce beneficial organisms in micropropagation plants as control measure. Inoculated treatments were T1 Trichoderma harzianum (Th), T2 T. virens (Tv), T3 T. aureoviride (Ta), T4 Bacillus subtilis (Bs), T5 Tv + B, Ta + B T6, T7 absolute control (Tabs) and T8 regional control (Treg). Treatments were established in a randomized block design with two replications, the experimental unit (EU) consisted of 122 plants; the minimum sample size was 26 plants. Evaluated variables were colony forming units (CFU) of Trichoderma, Fusarium spp. and Bacillus from roots and substrate and plant height, chlorophyll from plants. Variables were evaluated every 30 days from October 2008 to May 2009. Area under curve (AUC) was calculated for each variable. Our results show that microorganism in the treatments T1, T3, T4 and T6 colonized agave roots and maintain high levels, creating a balance to Fusarium spp. in soil and roots. Under this conditions Fusarium density ranged from 2 to 2.5 log (CFU/mL-1). Analysis of variance did not detect any significant difference among treatments. However, Fusarium spp. density on soil (AUC) was higher in treatments T8 Treg (120) and T7 Tabs (75.75) compared with the rest of treatments (50 or less). Fusarium density on roots was higher on treatments T6 Ta + B (375) and T7 Treg (262.5) compared to T3 Ta (105), T5 Tv + B (187.5), and T1 T4 Th B (210). No significant differences were found on chlorophylls and plant heights. [ABSTRACT FROM AUTHOR]

During 2010 in Nopaltepec, Mexico, cactus plants were detected with symptoms of distortion and thickening of the cladode, mosaic, yellowing, proliferation and deformation of fruits in the whole plant or part of it. Since the syndrome has been attributed to phytoplasma infection, the objective of this study was to detect, the presence of phytoplasmas in different strata of the cladode and the roots of cactus plants by Polimerase Chain Reaction (PCR). The DNA extracted from cladodes with symptoms and asymptomatic, was amplified firstly with universal primers P1/P7, and P1/Tint, fragment of phytoplasma 16S rRNA gene, followed by nested PCR using the primers R16F2/R16R2, a fragment of 1 200 bp was obtained. Analysis of restriction patterns generated with endonucleases revealed that the phytoplasma belongs to the Mexican periwinkle virescence-16SrXIII. [ABSTRACT FROM AUTHOR]

The chilli (Capsicum annuum) CM334 is resistant to oomycete Phytophthora capsici (Pc), such resistance is manifested by a hypersensitive reaction (HR); however, this genotype is susceptible to Fusarium oxysporum (Fo). In this study we compared the cellular changes in the HR-induced by Pc, incompatible interaction (II), and Fo-induced necrosis, compatible interaction (CI). The necrosis and colonization by the oomycete in II was confined to the site of inoculation in the stem, and in CI, the pathogen colonized the whole stem and the necrosis was limited to the site of inoculation. Cell wall degradation was evident in the CI, whereas in the II, only the collapse of the cells was observed. In the II, 31% of the nuclei of cortical cells were red suggesting a HR and in the CI 71% of the nuclei were globose and light gray suggesting a death by necrosis. [ABSTRACT FROM AUTHOR]

A subtractive library of sequences associated to proteins synthesis in hyphal germination of Sclerotium cepivorum was generated. In order to generate the subtractive library, optimal conditions to have eruptive and hyphal germination of S. cepivorum sclerotia were determined. At 22º C, 96.7% of sclerotia germinated hyphally without allyl disulfide (DAS) and 91.67% of sclerotia germinated eruptively in presence of DAS 2%. Twenty three fragments of genes associated to hyphal germination of S. cepivorum were obtained in the subtractive library. Those fragments had significant similarity to 15 different proteins that participate in respiration, transcription, translation, signal transduction and amino acid and protein synthesis process. The results suggest that hyphal germination is faster than eruptive germination because have an increment in the metabolic processes in sclerotia of S. cepivorum germinated hyphally. [ABSTRACT FROM AUTHOR]

Guava trees (Psidium guajava) are affected by guava decline in Calvillo, Aguascalientes, and Apozol, Zacatecas, Mexico. Symptoms like chlorosis and reduction of leaf area, reduction in fruit production and leaf rosetting, were associated with trees affected by the disease. The relationship between the presence of the disease and severity, and nutritional deficiencies, were determined by comparing foliage samples and soil from trees affected by decline and from those apparently free of the disease. Foliar and soil samples were collected from guava orchards to determine the concentration of N, P, K, Ca, Mg, Fe, Mn, and Zn. Electrical conductivity, pH, and soil organic matter content were also determined. DRIS indexes and indexes of nutrients unbalances were calculated by computer programs. Most soil samples showed deficiency of N, Mg, Fe, and Zn; while P, Ca, Fe, Mn, and Zn deficiencies were found in the foliage. The disease was related with the index of nutrient unbalance (r = 0.999), as well as with deficiency of Zn and Mn in the foliage, the presence of root knot nematode, and Fusarium solani. [ABSTRACT FROM AUTHOR]