Karina López-López

Weeds and economically important crops (tomato, pepper and passion fruit) in Valle del Cauca are currently affected by viruses of the Begomovirus genus, including PLDV, RhGMCV, PRMV, PYMV, and CroGMV. This study aimed to identify weed species associated with crops of agronomic interest that may serve as natural reservoirs of these viruses. Leaf samples were collected from various weeds in crop fields across Candelaria, Cerrito, and Palmira, and total DNA was extracted. Virus detection was performed by PCR using both universal Begomovirus primers and specific primers for PLDV, RhGMCV, PRMV, PYMV, and CroGMV. The incidence of each Begomovirus was analyzed by host species. Among the 16 samples collected, RhGMCV was the most prevalent virus (31.25%), followed by PRMV (25%) and PLDV (12.5%). PYMV and CroGMV were not detected. Corchorus orinocensis was found to be singly infected with RhGMCV, marking, to the best of our knowledge, the first report of this species as a host for Begomovirus. Tithonia diversifolia, Malvastrum coromandelianum, and Solanum nigrum were also identified as new reservoirs in Colombia, each exhibiting single infections with RhGMCV, PRMV, or an uncharacterized Begomovirus. Macroptilium lathyroides presented a mixed infection with PRMV, PLDV, and RhGMCV. These findings expand the known range of natural Begomovirus reservoirs in Valle del Cauca and contribute valuable data for the development of targeted management strategies to mitigate viral disease in crops of agricultural importance.

Yellow passion fruit crop is affected by multiple phytosanitary problems. Among the main ones are viruses of the genera Potyvirus (soybean mosaic virus, SMV), Cucumovirus (cucumber mosaic virus, CMV), Tymovirus (tymovirus passiflorae, PYMV) and Begomovirus (passionfruit leaf distortion virus, PLDV). Information about the prevalence and interaction between these viruses is scarce. The objective of this study was to verify the prevalence and identify the types of mixed viral infections of potyvirus, cucumovirus, tymovirus, and begomovirus in passion fruit crops in Valle del Cauca, Colombia. Passion fruit leaf samples with symptoms were collected and their nucleic acids were purified. Virus identification was performed by PCR using universal primers by viral genus, and specific primers for the SMV, CMV, PFYMV and PLDV viruses. The incidence of each virus by municipality was analyzed and the severity of the symptoms was compared with the diagnosis made. In total, 66 samples were collected in the municipalities of Toro, Dagua, Roldanillo, Bolívar, La Unión and El Cerrito. It was established that the most prevalent viruses are PLDV followed by SMV and CMV. The presence of PYMV was not detected in the samples analyzed. The presence of double and triple infections among potyvirus, cucumovirus and begomovirus were identified for the first time, finding greater severity of symptoms with a greater number of viruses identified per sample. This research provides key results for the design of control strategies for viral diseases in passion fruit.

En las infecciones mixtas entre begomovirus, comunes en regiones tropicales y subtropicales, eventos como transcomplementación y transreplicación pueden ocurrir. El objetivo de esta investigación fue evaluar la posibilidad de eventos asimétricos de transreplicación y transcomplementación entre el Virus del mosaico amarillo de la papa (PYMV) y tres begomovirus previamente aislados de arvenses asociadas al cultivo de tomate: Virus del mosaico dorado de croton (CohGMV), Virus del mosaico dorado de rhynchosia de Colombia (RhGMCV) y el Virus moteado de verbena (VeMV). Para alcanzar este objetivo, se inocularon hojas de tomate con mezclas artificiales de componentes genómicos begomovirales pertenecientes a PYMV, CohGMV, RhGMCV o VeMV usando biobalística. Se analizaron las posibles interacciones entre los virus a nivel de replicación, movimiento y expresión de síntomas. Nuestros resultados mostraron complementación simétrica a nivel de movimiento y replicación, además de eventos de transactivación heteróloga en infecciones mixtas entre PYMV con CohGMV, RhGMCV o VeMV. Para explicar la posible complementación asimétrica a nivel de movimiento y replicación entre estos begomovirus, se realizó un análisis bioinformático de los promotores virales de PYMV, CohGMV, RhGMCV y VeMV. Se identificaron similitudes en los elementos cis-regulatorios de las regiones analizadas entre los begomovirus estudiados en nuestro análisis. Los eventos de complementación asimétrica y transactivación observados bajo condiciones experimentales sugieren que, de presentarse infecciones mixtas bajo condiciones naturales en el campo, podrían potencialmente emerger nuevos pseudorecombinantes.

Nitrogen (N) is essential for amino acid synthesis in rice production, but its excessive use poses an environmental concern. This research aimed to improve rice agronomic nitrogen use efficiency (ANUE) by knockout (KO) of rice homologs of the two selected genes from Arabidopsis thaliana: AtAAP2, an amino acid permease involved in N transportation in shoots, and AtCRF4, a transcription factor participating in N uptake in roots. The homologs of these genes in rice were identified based on amino acid sequence similarity and knocked out using CRISPR/Cas9 mediated gene editing (GE). The AAP2-KO and CRF4-KO lines were subjected to agronomic evaluations with three N doses: 100% (180 kg ha-1), 50% (90 kg ha-1), and 0% (0 kg ha-1) and showed a 130-175% increase in dry biomass weight and a 183-313% increase in panicle number compared to wild type (WT) in the first experiment. These lines also had slower leaf senescence, the so-called “stay-green” trait, indicating the KO effect of target genes in N metabolism. However, neither AAP2-KO nor CRF4-KO showed better yield or ANUE than WT. This study demonstrated the usefulness of GE technology in gene evaluation and highlighted the effects of AtAAP2 and AtCRF4 genes in the plant N cycle.

Background and Aim: The pathogenicity of Escherichia coli is determined by the presence of genes that mediate virulence factors such as adherence capacity and toxin production. This research aimed to identify the adhesion factors and antibiotic resistance capacity of E. coli strains associated with diarrhea in piglets in Colombia. Materials and Methods: Presumptive E. coli strains were isolated from the rectal swabs of piglets in swine farms between 4 and 40 days of age with evidence of diarrhea. Presumptive E. coli strains were tested for antibiotic resistance. The hemolytic capacity of presumptive E. coli strains was measured and molecularly identified. Strains confirmed as hemolytic E. coli was evaluated for the presence of five adhesion factors (F4, F5, F6, F18, and F41) and resistance to 11 antibiotics. Results: Fifty-two putative E. coli strains were isolated, six of which showed a hemolytic capacity. The hemolytic strains were molecularly identified as E. coli. Adhesive fimbriae were found in five of six β-hemolytic E. coli isolates. Combinations of the adhesion factors F6–F18 and F6–F41 were linked to antibiotic resistance capacity. Conclusion: The phenomenon of E. coli strains resistant to multiple antibiotics on pig farms represents a constant risk factor for public health and pig production. Keywords: adhesive fimbriae, piglet diarrhea, enteroaggregative heat-stable toxin 1, enterotoxigenic Escherichia coli, hemolytic capacity.

En los últimos años, el ají (Capsicum chinense, Capsicum frutescens y Capsicum annuum var. Acuminatum), cultivado en el Valle del Cauca, se ha visto afectado por enfermedades virales causadas por Cucumber mosaic virus (CMV-ají) y Pepper severe mottle virus (PepSMoV). Pese a que estos dos virus son limitantes para producción del cultivo de ají, en la actualidad, pocos estudios han identificado los hospederos alternos de CMV-ají y PepSMoV. En este trabajo, se evaluó la presencia de CMV-ají y PepSMoV, mediante RT-PCR, en muestras de tejido foliar, de 121 plantas arvenses, asociadas al cultivo de ají, en el Valle del Cauca, Colombia. El análisis molecular indicó la presencia de CMV-ají, en el 21,4 % de las plantas recolectadas y de PepSMoV, en el 20,6 %. Se identificaron las especies arvenses Amaranthus viridis, Parthenium hysterophorus, Hippobroma longiflora, Commelina diffusa, Clitoria ternatea, Crotalaria incana, Desmodium tortuosum, Desmodium intortum, Macroptilium lathyroides, Anoda acerifolia, Boerhavia erecta, Bougainvillea glabra, Rivina humilis, Browallia americana, Capsicum rhomboideum, Solanum americanum y Lantana camara, como hospederas de CMV-ají o PepSMoV. Se presentó infección mixta de CMV-ají y PepSMoV, en 57 % de las arvenses positivas a virus, las cuales, están distribuidas en zonas productores de ají, localizadas en seis municipios del Valle del Cauca. Estos resultados brindan información sobre la distribución de estos virus en el Valle del Cauca, contribuyen al conocimiento de la epidemiología viral y servirán para diseñar medidas de manejo, orientadas a prevenir las infecciones virales en los cultivos de ají.

Los hidrocarburos aromáticos monocíclicos: benceno, tolueno, etilbenceno y xileno (BTEX), presentes en crudo y refinados de petróleo, hacen parte de los compuestos con más impacto en el medio ambiente y la salud humana, debido a su naturaleza cancerígena, mutagénica y altamente tóxica. Esta investigación tuvo como objetivo obtener y caracterizar bacterias capaces de degradar tolueno. Se realizaron tres muestreos de suelo contaminado con hidrocarburos del Valle del Cauca en tres condiciones: gasolinería, derrame accidental y taller mecánico. Se aislaron bacterias capaces de crecer en tolueno vapor como única fuente de carbono y se caracterizaron a nivel morfológico, bioquímico y molecular. Para la caracterización molecular se amplificó, secuenció y analizó con herramientas bioinformáticas el gen ribosomal 16S. Se evaluó la utilización de tolueno directo con concentración al 1% como única fuente de carbono. Se logró aislar 29 bacterias con capacidad de metabolizar tolueno. La caracterización bioquímica y molecular identificó a las bacterias aisladas de suelo contaminado como Pseudomonas y Stenotrophomonas. Las bacterias aisladas en el taller mecánico resultaron ser los microorganismos con mejor crecimiento en tolueno como fuente de carbono, poseen un gran potencial para ser utilizadas para fines de biorremediación de suelos y aguas contaminadas con BTEX. Monocyclic aromatic hydrocarbons: benzene, toluene, ethylbenzene, and xylene (BTEX), present in crude oil and refined petroleum products, they are the compounds with a big impact on the environment and human health, due to their carcinogenic, mutagenic, and highly toxic. This research aimed to obtain and characterize bacteria capable of degrading toluene. Three samples of soil contaminated with hydrocarbons were carried out in three different conditions: oil station, accidental oil spill, and mechanical workshop. Bacteria capable of growing in toluene vapor as the unique carbon source were isolated and characterized at a morphological, biochemical, and molecular level. For molecular characterization, the 16S ribosomal gene was amplified, sequenced, and analyzed with bioinformatic tools. The use of direct toluene with 1% concentration as the sole carbon source was evaluated. It was possible to isolate 29 bacteria with the capacity to metabolize toluene. Biochemical and molecular characterization identified bacteria isolated from contaminated soil as Pseudomonas and Stenotrophomonas. The isolated strains in the mechanical workshop were the microorganisms with the best growth in toluene as a carbon source, they have great potential to be used for the bioremediation of soils and waters with toluene pollution.

Los virus Potato yellow mosaic virus (PYMV/Co), Passionfruit leaf distortion virus (PLDV), Pepper rugose mosaic virus (PRMV) y Rhynchosia golden mosaic Colombia virus (RhGMCV) son begomovirus de interés agrícola, aislados y caracterizados molecularmente en el Valle del Cauca. Sin embargo, en la actualidad no hay suficiente información sobre sus hospederos alternos. Dado que las arvenses cumplen un papel importante en la ecología y epidemiología viral, este estudio tuvo como objetivo detectar la presencia de estos begomovirus en arvenses asociadas al cultivo de ají en el Valle del Cauca, Colombia. Se recolectaron 121 plantas arvenses en zonas productoras de ají, localizadas en 7 municipios del Valle del Cauca, las cuales fueron identificadas a nivel taxonómico. A partir del ADN genómico purificado de estas plantas se evaluó la presencia de virus por PCR, usando cebadores universales para el género Begomovirus y específicos para PYMV/Co, PLDV, PRMV y RhGMCV. Se detectaron begomovirus en 15 de las especies de arvenses evaluadas. Esta es la primera vez que las especies Ipomoea tiliacea, Melothria pendula, Caperonia palustris, Desmodium tortuosum, Desmodium intortum, Ammannia coccinea, Panicum polygonatum, Capsicum rhomboideum, Eclipta prostrata y Synedrella nodiflora se reportan como hospederas de begomovirus en Colombia. Se detectaron los begomovirus RhGMCV, PYMV/Co, PRMV y PLDV en infecciones simples y mixtas. Estos resultados aportan nuevos datos sobre los hospederos alternos de begomovirus. Esta información servirá para implementar un plan de manejo integrado de enfermedades virales con el potencial para afectar negativamente el rendimiento del cultivo de ají, y otros cultivos en Colombia.