Comparación de los factores internos que inciden en el metabolismo del CO2 en plantas C3 y C4

The Earth is facing two major threats, the first is global warming, which is reaching an alarming stage, and the second is the world population which is also expanding rapidly. Environmental factors affect the most fundamental biological process including photosynthesis and different metabolic pathways to assimilate CO2 from the environment. Therefore, the present study focused on characterizing the internal factors affecting CO2 metabolism of C3 and C4 plants. Consequently, these plants have different carbon assimilation, anatomical and biochemical characteristics. Most land plants, including important crops such as rice, soybean, wheat and potato, assimilate atmospheric CO2 via the Calvin cycle as a three-carbon (3C) compound, 3-phosphoglycerate (3-PGA), also known as the C3 pathway of photosynthesis. In this process, the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) plays an important role in the assimilation of atmospheric CO2 and, under stress conditions, this enzyme has more affinity for O2, resulting in the opposite process to photosynthesis, photorespiration. However, during evolution, warm environments and plants with C4 photosynthesis evolved, with a series of distinct properties (in particular, the anatomy of the Kranz leaf and the division of the cycle between two cell types) that allowed the capture of CO2 in a 4C compound (Oxaloacetate) and its concentration in the vicinity of Rubisco, in order to reduce the oxygenase activity of that enzyme and, therefore, the rate of photorespiration.

The Earth is facing two major threats, the first is global warming, which is reaching an alarming stage, and the second is the world population which is also expanding rapidly. Environmental factors affect the most fundamental biological process including photosynthesis and different metabolic pathways to assimilate CO2 from the environment. Therefore, the present study focused on characterizing the internal factors affecting CO2 metabolism of C3 and C4 plants. Consequently, these plants have different carbon assimilation, anatomical and biochemical characteristics. Most land plants, including important crops such as rice, soybean, wheat and potato, assimilate atmospheric CO2 via the Calvin cycle as a three-carbon (3C) compound, 3-phosphoglycerate (3-PGA), also known as the C3 pathway of photosynthesis. In this process, the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) plays an important role in the assimilation of atmospheric CO2 and, under stress conditions, this enzyme has more affinity for O2, resulting in the opposite process to photosynthesis, photorespiration. However, during evolution, warm environments and plants with C4 photosynthesis evolved, with a series of distinct properties (in particular, the anatomy of the Kranz leaf and the division of the cycle between two cell types) that allowed the capture of CO2 in a 4C compound (Oxaloacetate) and its concentration in the vicinity of Rubisco, in order to reduce the oxygenase activity of that enzyme and, therefore, the rate of photorespiration.

La Tierra se enfrenta a dos grandes amenazas, la primera es el calentamiento global, que alcanza una etapa alarmante, y la segunda es la población mundial que también se está expandiendo rápidamente. Los factores ambientales afectan el proceso biológico más fundamental, incluida la fotosíntesis y diferentes vías metabólicas para asimilar el CO2 del ambiente. Por lo que el presente estudio se centró en la caracterización de los factores internos que inciden en el metabolismo del CO2 de plantas C3 y C4. En consecuencia, estas plantas tienen diferentes características de asimilación de carbono, anatómicas y bioquímicas. La mayoría de las plantas terrestres, incluidos los cultivos importantes como el arroz, la soja, el trigo y la papa, asimilan el CO2 atmosférico mediante el ciclo de Calvin como un compuesto de tres carbonos (3C), 3-fosfoglicerato (3-PGA), también conocido como vía C3 de la fotosíntesis. En este proceso, la enzima ribulosa-1,5-bisfosfato carboxilasa / oxigenasa (Rubisco) juega un papel importante en la asimilación del CO2 atmosférico y, en condiciones de estrés, esta enzima tiene más afinidad por O2, lo que resulta en el proceso contrario a la fotosíntesis, la fotorrespiración. Sin embargo, durante la evolución, se desarrollaron ambientes cálidos y plantas con fotosíntesis de C4, con una serie de propiedades distintas (en particular, la anatomía de la hoja de Kranz y la división del ciclo de entre dos tipos de células) que permitían la captura de CO2 en un compuesto de 4C (Oxalacetato) y su concentración en las proximidades de Rubisco, con el fin de reducir la actividad oxigenasa de aquella enzima y, por tanto, la tasa de fotorrespiración. Palabras clave: células del mesófilo, células de la vaina del haz, ciclo de Calvin, fijación de carbono, fotosíntesis, fotorrespiración, Rubisco.