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La pudrición de raíz y tallo, más conocida como “damping-off” es un problema recurrente en muchos cultivos y asociada a patógenos como Pythium sp. y Phytophthora sp., Phytophthora sojae; y una importante limitación para la producción mundial de soja. Previamente, se identificó a la accesión PI 408029 como una potencial fuente de nuevos genes de resistencia (Rps) a P. sojae. El objetivo de este estudio fue la identificación y el mapeo de los loci Rps asociados a la resistencia a las patotipos de P. sojae OH1 (vir 7), OH4 (vir 1a, 1c, 7), OH25 (vir 1a, 1b, 1c, 1k, 7), OH7 (1a, 2, 3a, 3b, 3c, 4, 5, 6, 7) y 1.S.1.1 (1a, 1b, 1k, 2, 3a, 3c, 4, 5, 6, 7, 8) en una población de líneas recombinantes (RIL) resultante del cruce entre Williams (susceptible a PRSR) y PI 408029 (resistente a PRSR). Un cruce específico entre Williams y PI408029 fue realizado en el Centro de Investigaciones de Wooster de la Universidad Estatal de Ohio y las líneas segregantes fueron avanzadas siguiendo el método de descendencia de semilla única hasta la F7. Un total de 93 RILs fueron genotipadas usando en Infinium Soy-6K Beadchip array y fenotipadas usando patotitpos de P. sojae OH4, OH7, OH25, y 1S.1.1. El mapeo se realizó usando la función de Kosambi para determinar recombinaciones significativas. Las asociaciones fenotipo-genotipo (GWAS) fueron analizadas con la función de intervalo de mapeo compuesto CIM. La resistencia fue conferida por uno o dos genes Rps dominantes, dependiendo del aislado de P. sojae. Se detectó un nuevo locus Rps en el cromosoma 13 relacionado con OH4 y OH25. El locus restante para OH7 y 1.S.1.1 se encontraba en un locus conocido en el cromosoma 3. Un análisis comparativo de secuencias entre PI 408029 y Williams82 (Wm82.a2.v1), seguido de una PCR cuantitativa en tiempo real de 14 genes, condujo a la identificación de 2 genes de proteínas resistentes a enfermedades con repeticiones ricas en leucina (Glyma.03g048100 y Glyma.03g037000)[1], que se expresaron de manera aumentada tras la inoculación en un ensayo de tiempo con 1.S.1.1, y un gen de proteína quinasa similar a receptores (Glyma.13g050500) y un TIR-NB-LRR[2] (Glyma.13g078200) con OH4 y OH25. Los genes y marcadores de este estudio podrían utilizarse en el mejoramiento de cultivares resistentes a Phytophthora y en futuros estudios sobre la respuesta cualitativa de defensa funcional frente a P. sojae. [1] Glyma genes (Glicine max) [2] Genes que contienen terminales Nucleotide Binding Site - Leucine Rich Repeat

Coffee berry borer (Hypothenemus hampei), is one of the main pests affecting coffee production worldwide. This pest feeds and reproduces inside the berry reducing its weight and quality, causing losses up to 50%. Some strains of Bacillus have plasmids that incorporate cry and cyt genes, whose products have toxic properties to insects. Bacillus thuringiensis and Bacillus pumilus have been evaluated as entomopathogenic. The objectives of this study was to determine the potential of two native Bacillus strains (B. thuringiensis Bt3971 and B. pumilus Bp4185) isolated from coffee ecosystem of Puerto Rico as biocontrol of coffee berry borer. The presence of a 12 kbp plasmid was confirmed in Bt3971 and Bp4185, and a 116 kDa protein with entomopathogenic potential from Bt3971. After 48 h of treatment, Bt3971 (A590=0.8, approximately 1010 CFU ml-1) caused 55% mortality and 82% at 72 h in a population of insects. Bp4185 strain, at 72 h caused 55% mortality (A590=1.0, approximately 1012 CFU ml-1) and 46% at 96 h (A590=0.8). Both native bacterial strains, adapted to the environmental conditions of Puerto Rico, have potential for biological control of coffee berry borer.

Field experiments were conducted to evaluate agronomic traits and response to foliar fungal diseases of five advanced triple hybrids of hard yellow maize (Zea mays L.) and three commercial hybrids. An A × B factorial experiment with eight treatments, four repetitions and the Tukey test was used to compare means of the treatments (P>0.05). The most limiting disease is rust. The agronomic characteristics of breeding lines: h1, h2, h3, h4 and h5 (triple hybrids) were evaluated and compared with h6, h7, and h8 (commercial hybrids). Field trials were conducted in two locations of Central Coast of Ecuador (Quevedo & Balzar). Both locations showed significant differences for agronomic traits; Balzar presented lower yield (6,205.46 kg ha-1) and greater severity of curvularia leaf spot (3.34 CIMMYT scale) compared to Quevedo (7,368.21 kg ha-1 and 2.47 CIMMYT scale). For hybrids, h6 had significantly lower yield (5,306.83 kg ha-1), compared to h5 (6,914.09 kg ha-1), h1 (7,211.80 kg ha-1), h3 (7,266.83 kg ha-1), and h8 (8,036.85 kg ha-1). Significant differences were also detected for the orthogonal comparison (INIAP hybrids) with 5,634.44 kg ha-1 and the promissory lines with 6,997.68 kg ha-1. The highest net profit was achieved with the hybrid h2 with USD 1,405.76 followed by the hybrid h1 with USD 1,385,92, obtaining a Benefit-Cost ratio of 2.32 and 2.30 respectively, which indicates that for each monetary unit invested, an additional USD 1.32 and 1.30 of profit was obtained for the two hybrids, respectively.

Field trials were conducted in two years to evaluate persistence of B. thuringiensis and Bacillus pumilus under field conditions. Strains of B. thuringiensis (3971) and B. pumilus (4185) were isolated from coffee agro-ecosystem in Puerto Rico. Field trials consisted in plots of nine coffee trees arranged in a randomized complete block design, sprayed with Bt-3971 and Bp-4185 at 108, 109, or 1010 colony forming units CFU ml-1 or non-inoculated. In year 1, B. thuringiensis and B. pumilus survived up to six months after inoculation. Monitoring carried out during year 2, re-confirmed the survival of Bt-3971 and Bp-4185 inoculated in coffee trees under field conditions. Overall, Bt-3971 had significantly more recovery rates than Bp-4185. However, the higher bacterial recoveries were 1.24x1013 CFU ml-1 in coffee trees treated with Bt-3971 and 2.48x1013 CFU ml-1 in coffee trees treated with Bp-4185 in year 1 and year 2, respectively, both sprayed with 1010 spores ml-1. B. thuringiensis (3971) and B. pumilus (4185) isolated from coffee fields of Puerto Rico are well adapted to the environmental conditions of the island, and are valuable biological control agents against coffee berry borer.

Phytoplasma are wall-less bacteria limited to the phloem vessels in higher plants. Diseases associated with phytoplasma, in the past, have not been a serious problem in Ecuador. Nevertheless, for climate change effects, their importance has been increasing suddenly. This research was focused on the detection of phytoplasma using nested Polymerase Chain Reaction (PCR), in potato(Solanum tuberosum L.), oil palm(Elaeis guineensis), and papaya (Carica papaya L.) plants. Phytoplasma-specific PCR amplifications were generated by nested PCR in 50% samples of Twisted neck syndrome in papaya, 38% potato samples showing Purple top symptoms, and in all the samples showing symptoms of Lethal wilt of oil palm. A continual increase in the incidence of Potato purple top was observed, and there is a high risk of contamination in the southern production zones of the country. In potato, results of this study are more closely related to Candidatus Phytoplasma subgroup 16SrI. Lethal wilt continues to be a major threat to oil palm production. In papaya, members of the group 16SrXIII-E produce a disease similar as reported in this study.

Bacterial canker of naranjilla or lulo (Solanum quitoense and Solanum pectinatum) is a new disease that could completely destroy naranjilla plants. The objectives of this study were to identify and characterize bacteria associated with canker wilt of naranjilla, and to determine the importance of wounds in the dissemination and transmission of bacterial canker.Symptoms of this disorder consist of dieback and leaves showing incurvature which was diagnostic to confirm bacterial wilt. Collapse of leaf panel on Nicotiana tabacum confirmed that the bacterium is phytopathogenic. This bacterium showed positive serological tests for Clavibacter michiganensis subsp. michiganensis, positive Gram reaction, growth on NCP 88, (ELISA+ GRAM+ NCP 88 +) as well as re-isolation through Koch postulates in Solanum cheesmanii. Aerial wounds appear to be the most important means for dissemination. More research is needed about the molecular characterization of the bacterium, and potential for the bacterium to be transmitted to other solanaceous crops. Keywords: emerging infectious crop diseases, Solanum quitoense, Solanum pectinatum, Solanum cheesmanii, Solanum hirsutum

Food-borne diseases (FDB) are responsible for causing approximately 600 million illnesses and 420,000 deaths per year. Biologically related FBDs are typically associated with ubiquitous microorganisms, with bacteria such as Li. monocytogenes, Escherichia coli, Salmonella and Staphylococcus aureus being frequently implicated. The use of probiotics is limited by adverse conditions, that can impair the stability of La. reuteri and the evaluation of its probiotic properties and effects on pathogenic bacteria. Therefore, it is crucial to develop effective strategies to protect probiotics during their use. This study was conducted aiming to determine the effect of microencapsulation by spray drying technique on the probiotic viability of La. reuteri on Li. monocytogenes under simulated gastric conditions. The research involved reconstituting, planting, and inoculating La. reuteri and Li. monocytogenes; determining fermentation kinetics; conducting spray drying microencapsulation; studying and characterizing of microencapsulation; testing for exopolysaccharides production; conducting temperature tests; assessing exposure to gastric conditions; and conducting antibiotic susceptibility and inhibition tests. Such investigations allowed the establishment of the exponential phase in Probiotic (PRO) culture medium at 18 h and in De Man, Rogosa and Sharpe agar (MRS) medium at 12 h, exopolysaccharide production positive and growth at different temperatures (1.95x1013 CFU/ml and 2.16x1012 CFU/ml), survival against gastric conditions (greater than 108 CFU/ml) and inhibitory effect of La. reuteri on Li. monocytogenes (halos larger than 2 mm). The probiotic La. reuteri microencapsulated in a binary matrix composed of inulin and maltodextrin expresses probiotic properties against Li. monocytogenes, which is responsible for FBD and great stability after undergoing simulated gastric conditions.