Mario Martín González-Chavira

Oxidative and Molecular Responses in Capsicum annuum L. after Hydrogen Peroxide, Salicylic Acid and Chitosan Foliar Applications

Hydrogen peroxide (H2O2) is an important ROS molecule (Reactive oxygen species) that serves as a signal of oxidative stress and activation of signaling cascades as a result of the early response of the plant to biotic stress. This response can also be generated with the application of elicitors, stable molecules that induce the activation of transduction cascades and hormonal pathways, which trigger induced resistance to environmental stress. In this work, we evaluated the endogenous H2O2 production caused by salicylic acid (SA), chitosan (QN), and H2O2 elicitors in Capsicum annuum L. Hydrogen peroxide production after elicitation, catalase (CAT) and phenylalanine ammonia lyase (PAL) activities, as well as gene expression analysis of cat1, pal, and pathogenesis-related protein 1 (pr1) were determined. Our results displayed that 6.7 and 10 mM SA concentrations, and, 14 and 18 mM H2O2 concentrations, induced an endogenous H2O2 and gene expression. QN treatments induced the same responses in lesser proportion than the other two elicitors. Endogenous H2O2 production monitored during several days, showed results that could be an indicator for determining application opportunity uses in agriculture for maintaining plant alert systems against a stress.

A Germin-Like Protein Gene (CchGLP) of Capsicum chinense Jacq. Is Induced during Incompatible Interactions and Displays Mn-Superoxide Dismutase Activity

A germin-like gene (CchGLP) cloned from geminivirus-resistant pepper (Capsicum chinense Jacq. Line BG-3821) was characterized and the enzymatic activity of the expressed protein analyzed. The predicted protein consists of 203 amino acids, similar to other germin-like proteins. A highly conserved cupin domain and typical germin boxes, one of them containing three histidines and one glutamate, are also present in CchGLP. A signal peptide was predicted in the first 18 N-terminal amino acids, as well as one putative N-glycosylation site from residues 44–47. CchGLP was expressed in E. coli and the recombinant protein displayed manganese superoxide dismutase (Mn-SOD) activity. Molecular analysis showed that CchGLP is present in one copy in the C. chinense Jacq. genome and was induced in plants by ethylene (Et) and salicylic acid (SA) but not jasmonic acid (JA) applications in the absence of pathogens. Meanwhile, incompatible interactions with either Pepper golden mosaic virus (PepGMV) or Pepper huasteco yellow vein virus (PHYVV) caused local and systemic CchGLP induction in these geminivirus-resistant plants, but not in a susceptible accession. Compatible interactions with PHYVV, PepGMV and oomycete Phytophthora capsici did not induce CchGLP expression. Thus, these results indicate that CchGLP encodes a Mn-SOD, which is induced in the C. chinense geminivirus-resistant line BG-3821, likely using SA and Et signaling pathways during incompatible interactions with geminiviruses PepGMV and PHYVV.

Analysis of Pathotypes of Colletotrichum lindemuthianum Found in the Central Region of Mexico and Resistance in Elite Germ Plasm of Phaseolus vulgaris

The pathotypes of 17 isolates of Colletotrichum lindemuthianum from the central region of Mexico were characterized to determine the genetic relationship among isolates from this region and other regions of Mexico, and to evaluate the resistance present in the elite germ plasm collection of Phaseolus vulgaris at INIFAP. Eight pathotypes were identified, including pathotype 292, which is reported for the first time in Mexico. The lack of isolates infecting cultivar TU carrying the Co-5 resistance gene suggests that this cultivar is a useful source of resistance. Six pathotypes produced susceptible reactions on only differential cultivars of Middle American origin, one pathotype on a single cultivar of Andean origin, and one pathotype on cultivars of both Middle American and Andean origin. Comparison of amplified fragment length polymorphism (AFLP) genotypes of 21 isolates confirmed suggestions that populations of C. lindemuthianum are comprised of asexually reproducing clonal lineages. Analysis of five different pathotypes of C. lindemuthianum on 21 elite genotypes of P. vulgaris identified four genotypes from different races of P. vulgaris resistant to all five pathotypes. This information will allow breeders and farmers to select the resistant genotypes most suited to their needs.

Antimutagenic and antioxidant activities of quebracho phenolics (Schinopsis balansae) recovered from tannery wastewaters.

Quebracho extracts are used in tannery due to their high concentration of phenolics. The Mexican tannery industry uses around 450 kg/m(3) of which, 150 kg/m(3) remains in wastewaters and are discharged in drain pipe systems or rivers. The quebracho phenolics recovered from tannery wastewater (QPTW) was characterized by HPLC. The antimutagenic and antioxidant activities as well as the microbiological quality were evaluated. Total phenolic content of QPTW was 621mg catechin equivalent/g sample. Gallic and protocatechuic acids were the major components characterized by HPLC. QPTW showed an inhibition range on aflatoxin B(1) mutagenicity from 16 to 60% and was dose-dependent. Antioxidant activity (defined as beta-carotene bleaching) of QPTW (64.4%) at a dose of 12.3mg/mL was similar to that of BHT (68.7%) at a dose of 0.33 mg/mL, but lower than Trolox (90.8% at a dose of 2.5mg/mL); meanwhile antiradical activity (measured as reduction of DPPH) (60.8%) was higher than that of BHT (50.8%) and Trolox (34.2%). Quebracho residues were demonstrated to be an outstanding source of phenolic acids and for research and industrial uses.

Identification of novel drought-tolerant-associated SNPs in common bean (Phaseolus vulgaris)

Common bean (Phaseolus vulgaris L.) is a leguminous in high demand for human nutrition and a very important agricultural product. Production of common bean is constrained by environmental stresses such as drought. Although conventional plant selection has been used to increase production yield and stress tolerance, drought tolerance selection based on phenotype is complicated by associated physiological, anatomical, cellular, biochemical, and molecular changes. These changes are modulated by differential gene expression. A common method to identify genes associated with phenotypes of interest is the characterization of Single Nucleotide Polymorphims (SNPs) to link them to specific functions. In this work, we selected two drought-tolerant parental lines from Mesoamerica, Pinto Villa, and Pinto Saltillo. The parental lines were used to generate a population of 282 families (F3:5) and characterized by 169 SNPs. We associated the segregation of the molecular markers in our population with phenotypes including flowering time, physiological maturity, reproductive period, plant, seed and total biomass, reuse index, seed yield, weight of 100 seeds, and harvest index in three cultivation cycles. We observed 83 SNPs with significant association (p < 0.0003 after Bonferroni correction) with our quantified phenotypes. Phenotypes most associated were days to flowering and seed biomass with 58 and 44 associated SNPs, respectively. Thirty-seven out of the 83 SNPs were annotated to a gene with a potential function related to drought tolerance or relevant molecular/biochemical functions. Some SNPs such as SNP28 and SNP128 are related to starch biosynthesis, a common osmotic protector; and SNP18 is related to proline biosynthesis, another well-known osmotic protector.

‘Dalia’, nueva variedad de frijol de grano tipo Flor de Junio para la región centro de México

El frijol tipo Flor de Junio, cuyo color de grano es de fondo crema con franjas rosas, se produce y consume en la region Centro de Mexico. Se describe el proceso de obtencion y caracteristicas de Dalia, una nueva variedad de frijol tipo Flor de Junio de raza Jalisco, derivada de la cruza de Flor de Junio Silvia por Flor de Mayo Anita realizada en el Campo Experimental Bajio en 2003. El proceso de seleccion se baso inicialmente en la sanidad y el ciclo de la planta, asi como en las caracteristicas comerciales del grano en siembras bajo condiciones alternas de riego y temporal. En su fase final se realizo seleccion asistida por marcadores moleculares (SAM) para seleccionar la progenie que tuviera simultaneamente los marcadores ROC11 y SW13, ligados a los genes I y bc3, cuya piramidacion confieren resistencia a todos los patotipos de los virus BCMV y BCMNV. Dalia es de habito de crecimiento indeterminado tipo 3, con guias de tamano medio y ciclo de cultivo intermedio de 105 dias de siembra a la madurez fisiologica, y resistente a BCMV y BCMNV. En un ensayo nacional de rendimiento y adaptacion, Dalia mostro un rendimiento similar a Flor de Junio Marcela, la variedad dominante en el mercado, pero en contraste con esta, una nula interaccion genotipo por ambiente, lo que indico amplia adaptacion y estabilidad de rendimiento. Dalia se recomienda para produccion bajo riego y temporal en las regiones de El Bajio y el Altiplano del centro de Mexico.

Profiling the transcriptome of Sclerotium cepivorum Berk related to white rot on garlic (Allium sativum Linnaeus)

1 Instituto Tecnológico de Celaya. Departamento de Ingeniería Bioquímica. Avenida Tecnológico y A. García-Cubas S/N. Colonia Alfredo V. Bonfil. Apartado postal 57, Celaya, Guanajuato, CP 38010, México. 2 Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias. Campo Experimental Bajío. Unidad de Biotecnología del Bajío. Carretera Celaya-San Miguel de Allende km 6.5. Apartado postal 112. Celaya, Guanajuato, CP 38010, México. 3 CA de Ingeniería de Biosistemas. Facultad de Ingeniería. Universidad Autónoma de Querétaro. C.P 76010. Santiago Zhang de Querétaro, Qro, México. 4 Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.

Diversidad genética de aislados de Rhizoctonia solani (Kuhn) de chile en México

Una de las principales limitantes para la produccion de chile son los hongos patogenos causantes de la enfermedad conocida como “marchitez del chile” o “secadera”. Esta enfermedad puede ser devastadora cuando las condiciones climaticas son favorables para el patogeno. A pesar de que se han intentado diferentes medios de control (quimicos y culturales) ninguno ha tenido exito. Una alternativa para su control es producir germoplasma resistente, sin embargo para poder establecer un programa de mejoramiento efectivo es necesario conocer la distribucion y diversidad genetica de los patogenos involucrados, particularmente de Rhizoctonia solani, que por su ubicuidad representa un peligro potencial en todas las zonas productoras. Por ello el objetivo fue caracterizar a R. solani en las zona Centro Norte de Mexico y determinar su diversidad genetica. Para cumplir con este objetivo se consideraron los estados de Chihuahua, Durango, Zacatecas, San Luis Potosi, Colima, Queretaro y Guanajuato donde en 2009 se colectaron plantas adultas de Chile con sintomas de marchitez, se aislo al hongo y se encontro una incidencia del 33%, encontrandose tanto en tallo como en raiz. Las celulas miceliales fueron multinucleadas, caracteristicas de las cepas patogenicas. Las pruebas de anastomosis demostaron la presencia en Mexico de los grupos GA4, GA-2.1, GA-IIB, GA-2IV, GA7, GA11, GA12 y GA13. La diversidad genetica de este hongo fue muy alta, de tal manera que las relaciones demostradas por la construccion de dendrogramas no muestran tendencias homogeneas pues los principales grupos formados contienen elementos de todos los estados.

Efecto de las giberelinas en el rendimiento de chile jalapeño ("Capsicum annuum" L.)

The pepper (Capsicum annuum L.) is an important crop in Mexico due to its growing demand in recent years. Therefore, alternatives should be sought to increase their production, one of them is the use of growth regulators, of which gibberellins are important growth regulators involved in mooring and fruit development, flowering, cell elongation and expansion in plants. In order to evaluate the effect of the application of gibberellins (GA3) on the yield of jalapeno pepper produced in greenhouse, the present investigation was carried out in two successive experiments. In experiment 1, five doses of gibberellins were evaluated: 0 (control), 10, 30, 50 and 500 mg L-1 that were sprayed in one and two applications. The fertilization in this experiment was with nutritive solution (N, P, K and microelements). In experiment 2 the same doses of GA3 were evaluated, also in one and two applications, but the fertilization was carried out with calcium nitrate and potassium nitrate soluble in water. In experiment 1, no increase in yield was detected. In contrast, in experiment 2, the 10 mg L-1 dose of GA3 in combination with the fertilization with calcium nitrate and potassium nitrate increased the yield of jalapeno pepper. The results show gibberellins as key elements combined with low fertilization to increase pepper production.

Transcriptome profiling of transgenic tobacco (Nicotiana tabacum cv. xanthi nc) expressing CchGLP gene from Capsicum chinense Jacq. reveals gene expression associated with stress tolerance

ABSTRACT Plants require effective sensing and responses to environmental stimuli, for example in the case of biotic and abiotic stresses. Reactive oxygen species (ROS) are well-recognised key signal molecules for the stress response. In previous work in our group, several transgenic tobacco lines were generated constitutively expressing a germin-like gene from Capsicum chinense (CchGLP), producing higher endogen levels of hydrogen peroxide that correlated with tolerance to geminivirus infections and drought stress. Differential transcriptomic analysis between transgenic tobacco lines of low (L1) and high (L8) CchGLP gene expression showed key changes in differential profiles related to the crosstalk between basal metabolism, biochemical and stress-related pathways that might explain the observed tolerant phenotype. Our results suggested that hydrogen peroxide levels modified transcriptomic pattern allowing tolerance in these tobaccos towards biotic and abiotic stresses. Constitutive production of endogen hydrogen peroxide in certain levels within the plants might allow plant protection for future adversely scenarios in global farming.