Singularidad ecofisiológica de los rasgos fotosintéticos e hidráulicos de las plantas vasculares antárticas.
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Date
2024
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
Deschampsia antarctica y Colobanthus quitensis son las únicas especies de plantas vasculares que han logrado colonizar naturalmente las condiciones climáticas extremas de la Antártida. Además de estar ampliamente distribuidas en casi toda la Antártida Marítima, desde los 62°S hasta los 68°S, D. antarctica se ha encontrado creciendo fuera de la Antártica, desde latitudes menores, alrededor de los 33°S, hasta la Patagonia, mientras que C. quitensis tiene una distribución más amplia a lo largo de toda la cordillera de los Andes (desde aproximadamente los 10°N hasta los 55°S). Bajo las condiciones antárticas, se ha reportado que la asimilación de carbono (AN) en ambas especies está limitada por la conductancia del CO2 a través del mesófilo foliar (gm), lo que está relacionado con características fuertemente xerofíticas como una alta masa foliar por área (LMA) y densidad foliar (LD), esenciales para sobrevivir en el severo clima antártico. Para sobrellevar esta restricción en la difusión del CO2 hacia los sitios de carboxilación en los cloroplastos, las propiedades cinéticas de la Rubisco de las especies antárticas muestran una alta especificidad por el CO2 (Sc/o) y altas tasas de recambio catalítico (kcatc). A pesar del conocimiento extenso sobre los rasgos fisiológicos de las plantas vasculares antárticas, persisten vacíos respecto a la singularidad de estos rasgos. Específicamente, se desconoce si estos rasgos están determinados exclusivamente por el clima antártico, haciéndolos únicos en las especies que crecen en la Antártica, o si también están presentes en poblaciones subantárticas de estas especies, así como en otras especies filogenéticamente relacionadas o que se consideran potenciales invasoras de la Antártica. El objetivo de esta tesis fue analizar las características fotosintéticas e hidráulicas de D. antarctica y C. quitensis creciendo en ambientes subantárticos y antárticos, así como las características de especies filogenéticamente relacionadas que crecen en climas extremos, incluyendo dos potenciales especies invasoras en la Antártica. Las evaluaciones incluyeron características anatómicas, rasgos funcionales fotosintéticos (gs, gm, vcmax) y características hidráulicas (Kleaf, max, o) en plantas cultivadas bajo diferentes regímenes térmicos. Nuestros resultados subrayan algunas singularidades en la adaptación de las plantas vasculares antárticas en respuesta a la temperatura, destacando su eficiencia hidráulica y capacidad fotosintética relacionada a ajustes anatómicos foliares.
Deschampsia antarctica and Colobanthus quitensis are the only vascular plant species that have naturally colonized the extreme climatic conditions of Antarctica. Besides being widely distributed across almost all of Maritime Antarctica, from 62°S to 68°S, D. antarctica has been found growing outside Antarctica, as far north as 33°S, including Patagonia, while C. quitensis has a broader distribution along the Andes Mountain range (approximately between 10°N to 55°S). Under Antarctic conditions, carbon assimilation (AN) in both species is reported to be limited by CO2 conductance through the leaf mesophyll (gm), which is related to strongly xerophytic characteristics such as high leaf mass per area (LMA) and leaf density (LD), essential for surviving the severe Antarctic climate. To overcome this restriction in CO2 diffusion to the carboxylation sites in the chloroplasts, the kinetic properties of Rubisco in Antarctic species show high specificity for CO2 (Sc/o) and high catalytic turnover rates (kcatc). Despite extensive knowledge about the physiological traits of Antarctic vascular plants, there are still gaps regarding the uniqueness of these traits. Specifically, it is unknown whether these traits are determined exclusively by the Antarctic climate, making them unique to species growing in Antarctica, or if they are also present in sub-Antarctic populations of these species, as well as in other phylogenetically related species or those considered potential invaders of Antarctica. The aim of this thesis was to analyze the photosynthetic and hydraulic characteristics of D. antarctica and C. quitensis growing in sub-Antarctic and Antarctic environments, as well as the characteristics of phylogenetically related species growing in extreme climates, including two potential invasive species in Antarctica. The evaluations included anatomical characteristics, photosynthetic functional traits (gs, gm, Vcmax), and hydraulic traits (Kleaf, εmax, πo) in plants grown under different thermal regimes. Our results highlight some singularities in the adaptation of Antarctic vascular plants in response to temperature, emphasizing their hydraulic efficiency and photosynthetic capacity related to adjustment in some anatomical leaf traits.
Deschampsia antarctica and Colobanthus quitensis are the only vascular plant species that have naturally colonized the extreme climatic conditions of Antarctica. Besides being widely distributed across almost all of Maritime Antarctica, from 62°S to 68°S, D. antarctica has been found growing outside Antarctica, as far north as 33°S, including Patagonia, while C. quitensis has a broader distribution along the Andes Mountain range (approximately between 10°N to 55°S). Under Antarctic conditions, carbon assimilation (AN) in both species is reported to be limited by CO2 conductance through the leaf mesophyll (gm), which is related to strongly xerophytic characteristics such as high leaf mass per area (LMA) and leaf density (LD), essential for surviving the severe Antarctic climate. To overcome this restriction in CO2 diffusion to the carboxylation sites in the chloroplasts, the kinetic properties of Rubisco in Antarctic species show high specificity for CO2 (Sc/o) and high catalytic turnover rates (kcatc). Despite extensive knowledge about the physiological traits of Antarctic vascular plants, there are still gaps regarding the uniqueness of these traits. Specifically, it is unknown whether these traits are determined exclusively by the Antarctic climate, making them unique to species growing in Antarctica, or if they are also present in sub-Antarctic populations of these species, as well as in other phylogenetically related species or those considered potential invaders of Antarctica. The aim of this thesis was to analyze the photosynthetic and hydraulic characteristics of D. antarctica and C. quitensis growing in sub-Antarctic and Antarctic environments, as well as the characteristics of phylogenetically related species growing in extreme climates, including two potential invasive species in Antarctica. The evaluations included anatomical characteristics, photosynthetic functional traits (gs, gm, Vcmax), and hydraulic traits (Kleaf, εmax, πo) in plants grown under different thermal regimes. Our results highlight some singularities in the adaptation of Antarctic vascular plants in response to temperature, emphasizing their hydraulic efficiency and photosynthetic capacity related to adjustment in some anatomical leaf traits.
Description
Tesis presentada para optar al grado de Magíster en Ciencias Forestales
Keywords
Plantas Análisis, Plantas Chile Patagonia, Plantas resistencia al frio