Identificación genética de bacterias aisladas de Sophora Spp. en Chile y asociadas a Sophora toromiro (Phill) Skottsb especie extinta en su hábitat natural
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Date
2025
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Universidad de Concepción
Abstract
Sophora toromiro es un arbusto endémico de Rapa Nui, extinto en estado silvestre, y que actualmente está en vías de reinserción a su hábitat natural. Pertenece a la familia Fabaceae. Estudios previos han inoculado la planta con bacterias extraídas de nódulos de ejemplares de Sophora spp., provenientes de Nueva Zelanda y Chile continental e insular, algunas de ellas resultando ser simbiontes efectivos. En la presente investigación se analizaron las relaciones filogenéticas de las cepas chilenas, amplificando los genes 16S rRNA y nodA y realizando un árbol de máxima verosimilitud para cada gen. También se realizó un Análisis de Secuencia Multilocus (MLSA), de los genes conservados 16S rRNA, glnII, recA, rpoB, a través de un árbol concatenado de máxima verosimilitud. Los resultados arrojaron que los géneros de las bacterias encontradas en los nódulos de Sophora spp., fueron Mesorhizobium, Brucella, Rhizobium, Bradyrhizobium, Paraburkholderia, Pseudomonas, Dyella y Collimonas. Estos tres últimos no han sido descritos como rizobios, pero al menos Dyella podría resultar ser una Rizobacteria Promotora del Crecimiento Vegetal (PGPR). Además, tres de las cepas que habían presentado mejores resultados en la nodulación y fijación de nitrógeno, se agrupan como la misma especie bacteriana, perteneciente al género Mesorhizobium y no se encontraron secuencias de bacterias descritas anteriormente con las que pudiese ser identificada.
Sophora toromiro is a shrub endemic to Rapa Nui, extinct in the wild and currently in the process of being reintroduced into its natural habitat. It belongs to the Fabaceae family. Previous studies have inoculated the plant with bacteria isolated from nodules of Sophora spp. specimens from New Zealand and continental and insular Chile. Some of these bacteria turned out to be effective symbionts. In this research work, the phylogenetic relationships of the Chilean strains were analyzed, amplifying the 16S rRNA and nodA genes and constructing a maximum likelihood tree for each gene. A Multilocus Sequence Analysis (MLSA) of the housekeeping genes 16S rRNA, glnII, recA, rpoB was also performed through a concatenated maximum likelihood tree. Results showed that the genera of the bacteria found in the nodules of Sophora spp. were Mesorhizobium, Brucella, Rhizobium, Bradyrhizobium, Paraburkholderia, Pseudomonas, Dyella and Collimonas. These last three have not been described as rhizobia, but at least Dyella could be a Plant Growth Promoting Rhizobacteria (PGPR). In addition, three of the strains that had best results in nodulation and in nitrogen fixation, were grouped as the same bacterial species within the genus Mesorhizobium, and different to previously described bacterial species.
Sophora toromiro is a shrub endemic to Rapa Nui, extinct in the wild and currently in the process of being reintroduced into its natural habitat. It belongs to the Fabaceae family. Previous studies have inoculated the plant with bacteria isolated from nodules of Sophora spp. specimens from New Zealand and continental and insular Chile. Some of these bacteria turned out to be effective symbionts. In this research work, the phylogenetic relationships of the Chilean strains were analyzed, amplifying the 16S rRNA and nodA genes and constructing a maximum likelihood tree for each gene. A Multilocus Sequence Analysis (MLSA) of the housekeeping genes 16S rRNA, glnII, recA, rpoB was also performed through a concatenated maximum likelihood tree. Results showed that the genera of the bacteria found in the nodules of Sophora spp. were Mesorhizobium, Brucella, Rhizobium, Bradyrhizobium, Paraburkholderia, Pseudomonas, Dyella and Collimonas. These last three have not been described as rhizobia, but at least Dyella could be a Plant Growth Promoting Rhizobacteria (PGPR). In addition, three of the strains that had best results in nodulation and in nitrogen fixation, were grouped as the same bacterial species within the genus Mesorhizobium, and different to previously described bacterial species.
Description
Tesis presentada para optar al título de Ingeniero Agrónomo
Keywords
Sophora toromiro (Phil.) Skottsb., Rizobios, Crecimiento vegetal