RESUMEN El uso del potencial biotecnológico de microorganismos nativos como bioinsumos está teniendo un gran impacto en los sistemas agrícolas. Las rizobacterias promotoras del crecimiento vegetal (PGPR), además de su efecto benéfico en el crecimiento de las plantas y de facilitar la disponibilidad de elementos del suelo, también tienen un efecto antagónico frente a diferentes patógenos. En este estudio se evaluaron mecanismos de promoción del crecimiento con énfasis en el antagonismo de bacterias PGPR aisladas de cultivos de caña de azúcar y tomate. El antagonismo contra Fusarium oxysporum f.sp lycopersici (Fol) se determinó mediante pruebas duales, inhibición de la germinación y producción de quitinasas y endoglucanasas. Se evaluaron 52 aislamientos y según sus resultados en pruebas duales se seleccionaron 10 para su posterior análisis. El aislado GIBI127 mostró el mejor porcentaje de Inhibición de la Germinación (IG) de Fol (59,29%). Luego, se calculó un índice de selección utilizando los resultados de IG, pruebas duales y mecanismos de promoción del crecimiento para seleccionar los cinco mejores aislamientos. Finalmente, estas bacterias fueron evaluadas en la producción de quitinasas y endoglucanasas utilizando el método de Miller. Como resultado, se evidenció la cepa GIBI419 (Burkholderia cepacia) como la de mayor producción de estas enzimas. Los aislados seleccionados tienen un potencial antagónico junto con características de promoción del crecimiento de las plantas, que pueden usarse para el desarrollo de inoculantes microbianos que permitan el establecimiento de sistemas agrícolas para el cultivo de tomate que sean sostenibles, eficientes y amigables con el medio ambiente.

ABSTRACT Use of biotechnological potential of native microorganisms as bio-inputs is having a great impact on agricultural systems. Plant Growth Promoting Rhizobacteria (PGPR), in addition to their beneficial effect on plant growth and on the availability of soil elements, also have an antagonistic effect against different pathogens. In this study, growth promotion mechanisms with emphasis on the antagonism of PGPR isolated from sugarcane and tomato crops were evaluated. Antagonism against Fusarium oxysporum f.sp lycopersici (Fol) was determined by dual tests, inhibition of germination and production of chitinases and endoglucanases. 52 isolates were evaluated and according to their results in dual tests 10 were selected for further analysis. Isolate GIBI127 showed the best percentage of Inhibition Germination (IG) of Fol (59.29%). Then, a selection index was calculated using results from gi, dual tests and growth promotion mechanisms to select five best isolates. Finally, these bacteria were evaluated for chitinases and endoglucanases production using Miller's method. As a result, strain GIBI419 (Burkholderia cepacia) showed a higher production of these enzymes. Selected isolates have antagonistic potential along with plant growth promotion characteristics, which can be used for the development of microbial inoculants which allow the establishment of agricultural systems for tomato cultivation that are sustainable, efficient, and environmentally friendly.

ABSTRACT In this study, 55 tomato genotypes from different geographical regions were evaluated with ISSR markers (Inter Simple Sequence Repeats). The seven ISSR primers originated 63 amplified bands, of which 90.48% were polymorphic. The cluster analysis based on the Nei-Li similarity coefficient using the average genetic clustering method (UPGMA) revealed the conformation of five clusters at a level of similarity of 72%. The ISSR technique did not discriminate tomato genotypes according to the species or region of provenance. The STRUCTURE analysis and the dendrogram did not reveal a genetic structure in the population evaluated. The genotypes of the species of S. pimpinellifolium, S. l. cerasiforme, S. lycopersicum and S. peruvianum were found consistently grouped, showing a close genetic relationship among them. A high genetic variation among the individuals within each of the groups formed was suggested by the AMOVA. The ISSR markers were effective in assessing the genetic diversity and structure of populations of tomato genotypes. The high genetic variability found in this study indicates the valuable genetic potential present in tomato germplasm, especially of wild species, which could be used for future breeding programs of the species.

ABSTRACT Much of the diversity of tomato is found in wild forms, the most important being the Solanum lycopersicum L. var. cerasiforme and S. pimpinellifolium. The objective of this research was to assess the genetic diversity of 30 introductions of cherry tomato with 36 microsatellite molecular markers. The study was conducted at the Plant Transformation Research Center (PTRC) of the University of California. A dendrogram was built using the Dice-Nei and Li similarity index and the UPGMA clustering method, where introductions were differentiated without preserving a distribution pattern obeying the geographical area of origin. A coefficient of genetic differentiation was found (Fst = 0.3474), showing a high genetic differentiation of the introductions; those from Brazil, Ecuador, and Peru were the most genetically diverse, presenting 100% of polymorphic loci. The molecular variance analysis indicated a variation of 11% between the groups and 89% within the same. The broad genotypic variability of the evaluated introductions favors the possibility of selecting those for genetic improvement and sustainable use of the species.

Resumen. La mayor diversidad genética del tomate (Solanum lycopersicum L.) en términos de características de calidad del fruto como sabor, aroma, coloración y contenidos de licopeno y b-caroteno se encuentra en especies silvestres. Este estudio evaluó las características agronómicas y de calidad del fruto de 30 introducciones de tomate cereza provenientes del banco de germoplasma de la Universidad Nacional de Colombia -Sede Palmira en ensayos realizados en la granja Montelindo de la Universidad de Caldas (1010 m sobre el nivel del mar; temperatura media, 22,8°C; precipitación promedio anual, 2200 mm; humedad relativa, 76%). Se usó un diseño experimental de látice rectangular 5 x 6, con 30 tratamientos (introducciones) y un testigo comercial (Sweet Million), 4 repeticiones/tratamiento y 5 plantas/repetición como unidad experimental. Se utilizaron descriptores sugeridos por el antiguo Instituto Internacional de Recursos Fitogenéticos, ahora Bioversity International. Los datos fueron analizados estadísticamente utilizando análisis de varianza y la prueba de promedios de Duncan a través del programa SAS. Adicionalmente se realizaron análisis de componentes principales y agrupamiento por dendrograma por medio del procedimiento Princom y Cluster de SAS (SAS Institute, Cary, NC). Seis componentes principales explicaron el 80,39% de la variabilidad morfológica de las introducciones evaluadas. Los materiales más promisorios en términos de peso promedio de fruto, producción por planta, rendimiento y contenidos de sólidos solubles, vitamina C y licopeno fueron IAC1624, IAC391, IAC3652, LA2131, IAC424, IAC1621, IAC426, LA1480 y IAC1688. La amplia variabilidad fenotípica de las introducciones evaluadas favorece la posibilidad de selección y mejoramiento genético en tomate por caracteres asociados a la producción y calidad del fruto.

Abstract. The greatest genetic diversity of tomato (Solanum lycopersicum L.) in terms of fruit quality characteristics such as flavor, aroma, color, and lycopene and b-carotene contents is found in wild species. This study evaluated the agronomic characteristics and fruit quality of 30 cherry tomato introductions of the germplasm bank of the Universidad Nacional de Colombia - Sede Palmira in trials conducted at the Montelindo experimental farm of the Universidad de Caldas (1010 m above sea level, average temperature 22.8 °C, average annual rainfall 2200 mm, 76% relative humidity). A 5 x 6 rectangular lattice experimental design was used with 30 treatments (introductions) and a commercial control (Sweet Million), 4 replicates/treatment, and 5 plants/replicate as experimental unit. The descriptors used were those suggested by the former International Plant Genetic Resources Institute, now Bioversity International. Data were statistically analyzed by ANOVA and Duncan's means test using the SAS program. In addition, principal component and cluster dendrogram analyses using the SAS Princom and Cluster procedure (SAS Institute, Cary, NC) were performed. Six principal components accounted for 80.39% of the morphological variability of the introductions evaluated. The most promising materials in terms of average fruit weight, yield per plant and per hectare, and soluble solids, vitamin C and lycopene contents were IAC1624, IAC391, IAC3652, LA2131, IAC424, IAC1621, IAC426, LA1480 and IAC1688. The broad phenotypic variability observed in the evaluated introductions favors the potential selection and breeding of tomato for traits associated with fruit production and quality.