Abstract
Climate change not only worries government representatives and organizations, but also attracts the attention of the scientific community in different contexts. In agriculture specifically, the cultivation and productivity of crops such as sugarcane, maize, and sorghum are influenced by several environmental factors. The effects of high atmospheric concentration of carbon dioxide ([CO2]) have been the subject of research investigating the growth and development of C4 plants. Therefore, this brief review presents some of the physiological and genetic changes in economically important C4 plants following exposure periods of increased [CO2] levels. In the short term, with high [CO2], C4 plants change photosynthetic metabolism and carbohydrate production. The photosynthetic apparatus is initially improved, and some responses, such as stomatal conductance and transpiration rate, are normally maintained throughout the exposure. Protein-encoding genes related to photosynthesis, such as the enzyme phosphoenolpyruvate carboxylase, to sucrose accumulation and to biomass growth and are differentially regulated by [CO2] increase and can variably participate owing to the C4 species and/or other internal and external factors interfering in plant development. Despite the consensus among some studies, mainly on physiological changes, further studies are still necessary to identify the molecular mechanisms modulated under this condition. In addition, considering future scenarios, the combined effects of high environmental and [CO2] stresses need to be investigated so that the responses of maize, sugarcane, and sorghum are better understood.
Highlights
The increased atmospheric concentration of carbon dioxide ([CO2 ]) is one of the factors responsible for global warming [1] and the consequent irreversible climate change for hundreds of years [2].This increase has been significant since the industrial revolution, and over the last 50 years, [CO2 ]levels have increased from 320 to 390 ppmv [3,4]
The understanding needs to include aspects of physiology, metabolic mechanisms, and molecular mechanisms regulated in this condition, especially with regard to the photosynthetic enzyme efficiency, osmotic adjustment, antioxidant metabolism, and secondary metabolite production, among other processes that may directly or indirectly influence the adaptability responses to the climatic condition
What is expected for the coming years are studies that involve physiological responses, secondary metabolism pathways, hormones, and mainly gene and protein profiles modulated by the combined effect, aiming at C4 plants more adapted to climatic diversities that are tolerant and productive
Summary
The increased atmospheric concentration of carbon dioxide ([CO2 ]) is one of the factors responsible for global warming [1] and the consequent irreversible climate change for hundreds of years [2]. Differential expression of dozens of genes related to photosynthesis and development in sugarcane plants [13] Environmental factors, such as water availability and temperature, are associated with a considerably increased atmospheric [CO2 ]. More than 1600 differentially expressed genes involved in photosynthetic processes and stress response mechanisms were identified in sugarcane under water deficiency [21]. Considering the interest in elucidating these responses in C4 plants (sugarcane, maize, and sorghum), this brief review approaches the main effects of high [CO2 ] through considering different exposure periods (time) and emphasizing mostly physiological aspects related to photosynthetic metabolism and differential gene expression, despite the lack of data in the literature
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