Articles
Can cacti alleviate global warming? Measurement of calcium oxalate crystal content and carbon dioxide fixation in cactus stem (Nopalea cochenillifera)
Article number
1434_31
Pages
223 – 230
Language
English
Abstract
Calcium oxalate (CaOx) crystals are insoluble salts formed when oxalic acid ([COOH]2) combines with calcium ions (Ca2+) to precipitate.
This biomineral is present in a wide variety of plants.
CaOx crystals are found in various plant tissues and organs in at least 215 families and approximately 74% of angiosperm families.
Some cactus is known to accumulate large amounts of biominerals such as CaOx in their stems, although their physiological functions are poorly understood.
In this study, we investigated the biomineral characteristics and accumulation of CaOx in Nopalea cochenillifera. This cactus is mainly used as a woody ornamental plant in Asia, but it is also used as a crop in various countries, including the Mediterranean, South America, the Middle East, and North Africa, showing its wide adaptability to various climate zones ranging from arid, semiarid to temperate zones.
First, we separated and extracted biominerals from N. cochenillifera cladodes and observed them using a scanning electron microscope (SEM). Elemental analysis of the isolated biominerals was performed using SEM-energy dispersive spectroscopy (EDS). The spectrum obtained by SEM-EDS matches that of CaOx.
Therefore, we clarified that most of the biominerals contained in N. cochenillifera are CaOx.
Then, we measured the carbon and CaOx contents in each cladode using 2-year-old plant (height: 70-80 cm, weight: approximately 1 kg). Then, it was revealed that the whole cladode contains approximately 40-60 mg g-1 dry weight of CaOx, and old cladodes tended to have a higher CaOx compared with younger cladodes.
Because some cacti (including N. cochenillifera) can grow to more than 5 m in height and several hundred kilograms in weight, they can serve as a long-term carbon fixation source that can be used even in arid regions because of their fast growth rate and large biomass.
This biomineral is present in a wide variety of plants.
CaOx crystals are found in various plant tissues and organs in at least 215 families and approximately 74% of angiosperm families.
Some cactus is known to accumulate large amounts of biominerals such as CaOx in their stems, although their physiological functions are poorly understood.
In this study, we investigated the biomineral characteristics and accumulation of CaOx in Nopalea cochenillifera. This cactus is mainly used as a woody ornamental plant in Asia, but it is also used as a crop in various countries, including the Mediterranean, South America, the Middle East, and North Africa, showing its wide adaptability to various climate zones ranging from arid, semiarid to temperate zones.
First, we separated and extracted biominerals from N. cochenillifera cladodes and observed them using a scanning electron microscope (SEM). Elemental analysis of the isolated biominerals was performed using SEM-energy dispersive spectroscopy (EDS). The spectrum obtained by SEM-EDS matches that of CaOx.
Therefore, we clarified that most of the biominerals contained in N. cochenillifera are CaOx.
Then, we measured the carbon and CaOx contents in each cladode using 2-year-old plant (height: 70-80 cm, weight: approximately 1 kg). Then, it was revealed that the whole cladode contains approximately 40-60 mg g-1 dry weight of CaOx, and old cladodes tended to have a higher CaOx compared with younger cladodes.
Because some cacti (including N. cochenillifera) can grow to more than 5 m in height and several hundred kilograms in weight, they can serve as a long-term carbon fixation source that can be used even in arid regions because of their fast growth rate and large biomass.
Authors
T. Horibe, S. Tsuchimoto
Keywords
biomineralization, cladodes, ornamental plant, scanning electron microscope, carbon
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