KEY MESSAGE : Agrobacterium tumefaciens strains differ not only in their ability to transform tomato Micro-Tom, but also in the number of transgene copies that the strains integrate in the genome. The transformation efficiency of tomato (Solanum lycopersicum L.) cv. Micro-Tom with Agrobacterium tumefaciens strains AGL1, EHA105, GV3101, and MP90, harboring the plasmid pBI121 was compared. The presence of the nptII and/or uidA transgenes in regenerated T(0) plants was determined by PCR, Southern blotting, and/or GUS histochemical analyses. In addition, a rapid and reliable duplex, qPCR TaqMan assay was standardized to estimate transgene copy number. The highest transformation rate (65 %) was obtained with the Agrobacterium strain GV3101, followed by EHA105 (40 %), AGL1 (35 %), and MP90 (15 %). The mortality rate of cotyledons due to Agrobacterium overgrowth was the lowest with the strain GV3101. The Agrobacterium strain EHA105 was more efficient than GV3101 in the transfer of single T-DNA insertions of nptII and uidA transgenes into the tomato genome. Even though Agrobacterium strain MP90 had the lowest transformation rate of 15 %, the qPCR analysis showed that the strain MP90 was the most efficient in the transfer of single transgene insertions, and none of the transgenic plants produced with this strain had more than two insertion events in their genome. The combination of higher transformation efficiency and fewer transgene insertions in plants transformed using EHA105 makes this Agrobacterium strain optimal for functional genomics and biotechnological applications in tomato.

In Colombia, tomato production under protected conditions represents an important economic contribution to the agricultural sector. Fusarium wilt diseases, caused by pathogenic formae speciales of the soil-borne fungus Fusarium oxysporum Schltdl., cause significant yield losses in tomatoes throughout the world. Investigation of the F. oxysporum–tomato pathosystem in Colombia is required to develop appropriate alternative disease management. In this study, 120 fungal isolates were obtained from four different departments in the Central Andean Region in Colombia from tomato crops with symptoms of wilt disease. A molecular characterization of the fungal isolates was performed using the SIX1, SIX3, and SIX4 effector genes of Fusarium oxysporum f. sp. lycopersici W.C. Snyder & H.N. Hansen (Fol). Additionally, we developed a new specific marker to distinguish between Fusarium oxysporum f. sp. radicis-lycopersici Jarvis & Shoemaker (Forl) and Fol isolates. Furthermore, a phylogenetic analysis using the Translation Elongation Factor 1-alpha (EF1a) gene was performed with the collected isolates. Two isolates (named Fol59 and Fol-UDC10) were identified as Fol race 2, four isolates were identified as Forl, six isolates were identified as F. solani, and most of the isolates were grouped within the F. oxysporum species complex. The phylogenetic tree of EF1a showed that most of the isolates could potentially correspond to nonpathogenic strains of F. oxysporum. Additional pathogenicity assays carried out with Fol59 and Fol-UDC10 confirmed that both isolates were highly virulent strains. This study represents a contribution to the understanding of the local interaction between tomatoes and F. oxysporum in Colombia.

Estudio técnico y económico del tomate tipo cereza élite (Solanum lycopersicum L. var. cerasiforme) bajo condiciones semicontroladas E S T U D I O T É C N I C O Y E C O N Ó M I C O D E L T O M AT E T I P O C E R E Z A É L I T EVol. 9 -No. 1 -2015Additional key words: profitability, productivity, cherry tomato. Fecha de recepción: 16-07-2015Aprobado para publicación: 20-11-2015 ABSTRACTThe cherry tomato, being a crop of fast economic return, has aroused the interest of producers, but there is little information on the costs of production and profitability in the domestic market, which prevents crop expansion. Thus, the objective of this study was to evaluate 10 economically elite introductions of cherry tomato under controlled conditions in the Colombian Andes.

Influence of plant growth-promoting rhizobacteria (PGPR) on blackberry (Rubus glaucusBenth , and commercial strain B. subtilis QST-713 were compared to conventional mineral fertilization (Control) in each cropping system. Field condition system presented higher values (P<0.001) than semi cover in: total number of branches (7.32), number of productive branches (7.0), flowers per raceme (26.2), and the lowest percentage of unproductive branches (6.1%). Significant differences (P<0.05) were obtained in total number of branches over time by bacterial strains. Nonetheless, last observation of this variable did not present statistical differences among strains and mineral fertilization. No significant differences were evident in terms of number, length, diameter and flowers in the productive branches regarding to bacterial strains and Control. B. subtilis GIBI-200 + B. pumilus GIBI-206 showed a similar statistical behavior compare to mineral fertilization in the number of clusters (8.3) and percentage of unproductive branches (11.1%). In addition, GIBI-200 + GIBI-206, despite statistical equality, exposed greater values than individual strains. Field condition system remains the most promising alternative for the development of blackberry crop and PGPR acts as biofertilizers achieving effects in the long-term growth of blackberry similar to mineral fertilization. Mixtures of PGPR can produce a synergic effect and new combinations should be evaluated in future studies.Key words: biofertilizers; cropping system; fruitculture; plastic film covers; soil microorganisms; symbiosis. ResumenEste estudio muestra el efecto de tres cepas de rizobacterias promotoras del crecimiento vegetal (PGPR) del género Bacillus sobre el desarrollo de la mora (Rubus glaucus Benth) bajo condiciones de semitecho y libre exposición (sistemas de cultivo). La cepa endógena Bacillus subtilis GIBI-200, B. pumilus GIBI-206, su mezcla (B. subtilis GIBI-200 + B. pumilus GIBI-206) y la cepa comercial B. subtilis QST-713 se compararon con la fertilización mineral convencional (Control) en cada sistema de cultivo. El sistema a libre exposición presentó valores más altos (P <0.001) que el semitecho en: número total de ramas (7.32), número de ramas productivas (7.0), flores por racimo (26.2) y menor porcentaje de ramas improductivas (6.1%). Se obtuvo diferencias significativas (P <0.05) en el número total de ramas a través del tiempo como efecto de las cepas bacterianas. No obstante, la última observación de esta variable no presentó diferencias estadísticas entre cepas y fertilización mineral. No se observaron diferencias significativas en términos de número, longitud, diámetro y flores en las ramas productivas como efecto de las cepas bacterianas y el Control. B. subtilis GIBI-200 + B. pumilus GIBI-206 mostró un comportamiento estadístico similar comparado con la fertilización mineral en el número de racimos (8.3) y porcentaje de ramas improductivas (11.1%). Además, GIBI-200 + GIBI-206, a pesar de la igualdad estadística, expuso mayores valores que las ce...

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.