Respuesta del “álamo chileno” (populus nigra var. italica) frente a condiciones de estrés abiótico. Evaluación del efecto del exceso de Germanio.
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Date
2024
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Universidad de Concepción
Abstract
La fitoextracción es una técnica prometedora y económica para mitigar la contaminación de suelos por metales pesados. Utiliza plantas, como por ejemplo, álamos (Populus spp.), para absorber y acumular metales en sus tejidos, involucrando proteínas especializadas y la expresión de genes específicos. Este estudio tuvo como objetivo evaluar la respuesta de Populus nigra var. italica (álamo chileno) frente al estrés por exceso de germanio (Ge). Las plantas, cultivadas en un sistema hidropónico, fueron expuestas a una concentración de 5 μM de óxido de Ge durante 21 horas, después de dos meses de crecimiento. Se evaluó la expresión de genes relacionados con el transporte de agua y metales, así como con mecanismos antioxidantes y quelantes peptídicos a nivel transcripcional. Adicionalmente, se realizó una caracterización elemental mediante espectrometría de fluorescencia de rayos X (XRF), y se analizaron las variables fisiológicas, conductancia estomática (gs) y tasa de transporte de electrones (ETR).
Los resultados mostraron que, aunque no hubo cambios significativos en la gs, se detectaron diferencias significativas en la ETR bajo estrés por Ge. Las concentraciones de Ge en los tejidos evaluados fueron indetectables con la técnica TR-XRF empleada. A nivel molecular, se observó una expresión diferencial de los genes NRAMP2 en hojas y MT2-L en raíces, lo que sugiere un mecanismo adaptativo frente al estrés por metales divalentes. Estos genes estarían implicados en la detoxificación de metales y la protección contra el estrés oxidativo, a pesar de la falta de acumulación detectable de Ge en los tejidos.
Populus nigra var. italica mostró respuestas fisiológicas y moleculares específicas frente al estrés inducido por Ge, sugiriendo su potencial en estrategias de fitorremediación. A pesar de que no se detectaron concentraciones significativas de Ge en los tejidos, los cambios en la expresión de genes clave sugieren la activación de mecanismos de adaptación que podrían aprovecharse en futuras investigaciones para optimizar la fitoextracción y mitigar la contaminación por metales pesados.
Phytoextraction is a promising and economical technique to mitigate heavy metal contamination of soils. It utilizes plants such as poplars (Populus spp.) to absorb and accumulate metals in their tissues through the expression of specific genes. The objective of this study was to evaluate the response of Populus nigra var. italica (Chilean poplar) to germanium (Ge) excess stress. Plants, grown in a hydroponic system, were exposed to a 5 μM concentration of Ge oxide for 21 hours after two months of growth. The expression of genes related to water and metal transport, as well as antioxidant and peptide chelating mechanisms was evaluated at the transcriptional level. In addition, elemental characterization was performed by X-ray fluorescence spectrometry (XRF), and the physiological variables stomatal conductance (gs) and electron transport rate (ETR) were analyzed. The results showed that, although there were no significant changes in gs, significant differences were detected in ETR under Ge stress. Ge concentrations in the tissues evaluated were undetectable with the applied technique. At the molecular level, differential expression of NRAMP2 genes in leaves and MT2-L in roots was observed, suggesting an adaptive mechanism against divalent metal stress. These genes would be involved in metal detoxification and protection against oxidative stress, despite the lack of detectable Ge accumulation in tissues. Populus nigra var. italica showed specific physiological and molecular responses to Ge-induced stress, suggesting its potential in phytoremediation strategies. Although no significant Ge concentrations were detected in tissues, changes in the expression of key genes suggest the activation of adaptive mechanisms that could be exploited in future research to optimize phytoextraction and mitigate heavy metal contamination.
Phytoextraction is a promising and economical technique to mitigate heavy metal contamination of soils. It utilizes plants such as poplars (Populus spp.) to absorb and accumulate metals in their tissues through the expression of specific genes. The objective of this study was to evaluate the response of Populus nigra var. italica (Chilean poplar) to germanium (Ge) excess stress. Plants, grown in a hydroponic system, were exposed to a 5 μM concentration of Ge oxide for 21 hours after two months of growth. The expression of genes related to water and metal transport, as well as antioxidant and peptide chelating mechanisms was evaluated at the transcriptional level. In addition, elemental characterization was performed by X-ray fluorescence spectrometry (XRF), and the physiological variables stomatal conductance (gs) and electron transport rate (ETR) were analyzed. The results showed that, although there were no significant changes in gs, significant differences were detected in ETR under Ge stress. Ge concentrations in the tissues evaluated were undetectable with the applied technique. At the molecular level, differential expression of NRAMP2 genes in leaves and MT2-L in roots was observed, suggesting an adaptive mechanism against divalent metal stress. These genes would be involved in metal detoxification and protection against oxidative stress, despite the lack of detectable Ge accumulation in tissues. Populus nigra var. italica showed specific physiological and molecular responses to Ge-induced stress, suggesting its potential in phytoremediation strategies. Although no significant Ge concentrations were detected in tissues, changes in the expression of key genes suggest the activation of adaptive mechanisms that could be exploited in future research to optimize phytoextraction and mitigate heavy metal contamination.
Description
Tesis presentada para optar al título de Ingeniero en Biotecnología Vegetal.
Keywords
Contaminación de suelos, Metales pesados Absorción y adsorción, Álamo Chile