Vascular wilt caused by Fusarium oxysporum is the most damaging disease in cape gooseberry (Physalis peruviana L.) production. In this study, we isolated and biochemically characterized endophytes and rhizospheric bacterial isolates with antagonistic activity against F. oxysporum from cape gooseberry plants. Bacterial isolates were evaluated under in vitro conditions for their antagonistic capacity against a highly virulent isolate of F. oxysporum, as well as production of lytic enzymes, biosurfactants and volatile organic compounds. Twenty-four antagonistic bacteria were selected, out of which Bacillus sp. MB015 and Pseudomonas sp. MB108 exhibited the best biocontrol activity in vitro, with inhibition levels of 80.6% and 79.9%, respectively. However, under greenhouse conditions, P. fluorescens MB103 and B. megaterium MB112 presented the best antagonistic capacity with 83.3% control of vascular wilt incidence. P. fluorescens MB103 was one of most effective in reducing the disease severity with an area under the disease of progress curve (AUDPC) of 7.5, compared with the negative control (soil infested with Fox17 without test bacteria), which presented an AUDPC of 36.8. These results suggest that P. fluorescens MB103 is a good candidate for use as a biocontrol agent against vascular wilt caused by F. oxysporum in cape gooseberry under field conditions.
Los microorganismos, esporas, ácaros y polen son componentes naturales del aire en ambientes internos y pueden ser transportados desde el exterior por partículas aerobiológicas que pueden establecerse en el polvo y causar el biodeterioro de diversos materiales, además de representar un riesgo para la salud de las personas. Con este trabajo, se evaluó la concentración microbiana en el ambiente de la Biblioteca Central Jorge Palacios Preciado, Universidad Pedagógica y Tecnológica de Colombia. Se empleó el método de sedimentación en placa para realizar el muestreo microbiológico del ambiente, utilizando agar Sabouraud para el aislamiento de hongos y agar nutritivo para bacterias. La densidad microbiana del ambiente se encontró dentro de los límites de sanidad aceptados para ambientes de lugares públicos, y la mayor diversidad identificada estuvo representada por 34 géneros de hongos filamentosos y un grupo de hongos de la clase Phycomycetes, siendo las esporas de los géneros Cladosporium, Paecilomyces y Penicillium, las más frecuentes en la biblioteca. Las levaduras fueron las menos representativas en el ambiente con dos géneros aislados Candida y Rhodotorula. En cuanto a las bacterias, se aislaron en total 16 géneros, de los cuales Bacillus y Neisseria, fueron los más comunes. Teniendo en cuenta los géneros microbianos aislados y las investigaciones más recientes, el ambiente de la Biblioteca Central podría representar un riesgo para la salud de las personas, principalmente a nivel respiratorio, sino se adoptan algunas medidas de limpieza y de adecuación de los sistemas de ventilación.
Bananas and plantains (Musa spp.) are one of the most important crops worldwide. The cultivated varieties are vegetatively propagated, and their diversity is essentially fixed over time. Nevertheless, millennia of diversification and selection have led to hundreds of edible varieties. M. acuminata and M. balbisiana respectively provided the A and B subgenomes that mostly constitute these varieties. Here we aimed to characterise chromosomal exchanges and structural variation among lineages to understand shared foundational events and identify sources of allelic diversity in introgressed loci for genetic improvement. We identified clonal somatic groups among 188 banana and plantain accessions introduced for cropping in Colombia, using admixture, principal component, and phylogenetic analyses. We established a new alignment-based metric, named Relative Averaged Alignment (RAA), to infer subgenome composition (AA, AAB, etc.). We later used comparisons in read coverage along conserved chromosomal windows between the A, B, and S subgenomes to identify introgressions. In our panel, we identify ten varietal groups composed of somatic clones, plus three groups of tetraploid accessions. We demonstrated RAA can be used to infer subgenome composition in the total genome and individual chromosomes. We identified 20 introgressions, several newly reported, among the AAB and ABB varieties. We did not observe B-donor introgression in any AA/AAA varietal groups. We identified variation in length in at least two introgressions, a B-donor introgression in chromosome 7 between the "Maoli" and a "Popoulu" subdivisions, and an S-donor (M. schizocarpa) introgression in chromosome 2 in four varietal groups with different compositions (AAA, AAB, ABB, and AA). The extensive distribution of introgressions and the variation in the length of some introgressions between varieties support that the emergence of many varieties can be attributed to intricate founding events, which encompassed multiple instances of hybridisation and subsequent residual backcrossing. We also showed the contribution of M. schizocarpa to four cultivated varieties, and proposed subdivision-specific intergenomic recombination in chromosome 7 between subgroups Maoli and Popoulu plantains. Introgressed loci over these 20 introgressions likely provide an extensive resource of allelic diversity to further explore their contribution to disease resistance, climatic adaption, etc. and potential for exploiting in breeding and genome editing.
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