大气中二氧化碳的减少以及CAM植物进化的时间
Rowan F Sage1, Ian S Gilman2, J Andrew C Smith3
1Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
Annals of botany
|August 29, 2023
概括
草酸代谢 (CAM) 光合作用可能在过去的3000万年里在低二氧化碳条件下演变. 虽然弱CAM可能早于此,但强CAM可能早于此.
科学领域:
- 植物生理学 植物生理学
- 进化生物学 进化生物学
- 古气候学 古气候学
背景情况:
- 草酸代谢 (CAM) 光合作用是一种水效的碳固定途径.
- 假设CAM的进化与低大气二氧化碳度和需要将二氧化碳集中在鲁比斯科周围的需求有关.
- 这项研究调查了CAM进化的时间相对于过去大气二氧化碳水平.
研究的目的:
- 为了测试CAM光合作用在应对大气二氧化碳的下降而演变的假设.
- 为了确定与地质二氧化碳波动相关的CAM的进化历史.
- 评估大气二氧化碳对CAM相对于C3光合作用相对优势的影响.
主要方法:
- 编制了73个含有CAM的族群的家族遗传时间表.
- 估计CAM类起源及其与大气二氧化碳估计的时间关系.
- 对二氧化碳对CAM和C3光合作用的影响的实验证据的审查.
主要成果:
- 据估计,强大的CAM在过去的3000万年里进化,与大气中的二氧化碳从800ppm下降到450ppm.
- 大多数CAM特异性基团起源于过去1500万年,反映了C4基团的起源.
- 证据表明,在高二氧化碳时期重复出现弱CAM进化,以及Crassulaceae中潜在的早期强CAM起源.
结论:
- 在过去的3000万年里,强大的CAM在减少的二氧化碳条件下多次演化.
- 升高的CO2通过增加C3光合作用贡献来减少强大的CAM的好处,使其进化不太可能.
- 较弱的CAM可能是在更高的CO2下演变的,可能是在水有限的环境中.
相关概念视频
C4 Pathway and CAM
45.6K
Most plants use the C3 pathway for carbon fixation. However, some plants, such as sugar cane, corn, and cacti that grow in hot conditions, use alternative pathways to fix carbon and conserve energy loss due to photorespiration. Photorespiration is the process that occurs when the oxygen concentration is high. Under such conditions, the rubisco enzyme in the Calvin cycle binds O2 instead of CO2, which halts photosynthesis and consumes energy.
C4 Pathway
The C4 pathway is used by plants such as...
C4 Pathway
The C4 pathway is used by plants such as...
45.6K
The Calvin Benson Cycle
4.6K
Ribulose 1,5- bisphosphate carboxylase/oxygenase (RuBisCo) is a critical enzyme that catalyzes carbon dioxide assimilation during photosynthesis. However, it is an inefficient enzyme, having an extremely slow catalytic rate. A typical enzyme can process about a thousand molecules per second; however, RuBisCo fixes only around three-carbon dioxides per second. Photosynthetic cells compensate for this slow rate by synthesizing very high amounts of RuBisCo, making it the most abundant single...
4.6K
Adaptations that Reduce Water Loss
25.7K
Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.
25.7K
Carbon-dioxide Fixation
37
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...
37
Global Climate Change
24.5K
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
24.5K
The Carbon Cycle
38.4K
Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle.
38.4K


