Determination of photosynthetic rate in Arabidopsis
Arabidopsis background information:
Arabidopsis thaliana is a cruciferous plant, widely used in the research of plant genetics, developmental biology and molecular biology, and has become a typical model plant.
(1) The individual shape of the plant is small, the height is only about 30cm, and one Tea Cup can plant several trees;
(2) The growth cycle is fast and the time of each generation is short. It usually takes about 6 weeks from sowing to harvesting seeds;
(3) There are many seeds, and each plant can produce thousands of seeds per generation;
(4) Simple morphological characteristics and strong vitality, it can be used for artificial cultivation with ordinary medium;
(5) The genome is small, with only 5 pairs of chromosomes.
Although Arabidopsis is "simple" in many ways, most of its genes have high homology with other "complex" plant genes. In addition, since the entire genome of this plant has been sequenced, it can be predicted that Arabidopsis will play a greater role in all fields of botany.
The Arabidopsis genome is currently the smallest of the plant genomes. The total length of each haploid chromosome group (n = 5) is only 70 million base pairs, which is only 1/80 of the length of the wheat chromosome group, which makes it relatively easy to clone its related genes. Arabidopsis thaliana is a self-pollinating plant. The gene is highly homozygous, and the mutation rate is high when treated with physical and chemical factors, and it is easy to obtain defective types of various metabolic functions. For example, screening with a herbicide-containing medium generally results in a mutation rate of 1/100000 for herbicide resistance. Because of these advantages, Arabidopsis thaliana is a good material for genetic research and is hailed by scientists as "Drosophila in plants". (The above background information is taken from Baidu Encyclopedia)
Photosynthesis is an important life phenomenon on the earth. It is a process that can convert solar energy into stable chemical energy and store it in organic matter. It is a key link to maintain the material circulation on the earth and a decisive factor in the formation of crop yields. Therefore, improving photosynthesis is very important for improving crop yields. As a model plant, Arabidopsis thaliana can further understand the photosynthesis-related genes of crops through related research on the functions of photosynthesis-related genes of Arabidopsis thaliana, and ultimately improve the utilization efficiency of light energy by crops, and fundamentally increase crop yield.
According to the total reaction formula of photosynthesis: CO2 + 2H2O + 4.69kJ → (CH2O) + O2 + H2O
In principle, we can determine the rate of consumption of any reactant or the rate of product formation to represent the rate of photosynthesis. A commonly used method for measuring photosynthetic rate is to measure the absorption of CO2 or the release of O2.
Based on the principle of determination of photosynthetic rate, there are mainly two methods to determine photosynthetic rate of Arabidopsis:
A oxygen electrode to measure the release of O2
Determination of CO2 absorption by B photosynthesis instrument
Determination of O2 release Determination of Arabidopsis photosynthesis:
The oxygen electrode measures the photosynthetic rate of the leaves in the reaction system by measuring the change of dissolved oxygen in the reaction system. The measurement data is accurate, and it is easy to obtain the accurate photosynthetic rate, and the accuracy is higher than that of the photosynthesis apparatus. Especially when studying genes related to the oxygen-releasing complex, the oxygen electrode must be used to measure the photosynthetic rate. Oxygen electrode can also be used to study the photosynthetic rate of many green organs of plants, which is unmatched by photosynthesis apparatus. The photosynthetic rate of plant materials with sedative acid metabolism pathway can only be measured with oxygen electrode.
Although the oxygen electrode is very accurate in measuring the photosynthetic rate of Arabidopsis thaliana, it has a wide range of use and is easy to operate, but it also has some disadvantages. The destructive sampling of the oxygen electrode cannot measure the transpiration rate, stomatal conductance, and intercellular CO2 concentration. The measured parameters.
Determination of CO2 absorption Determination of Arabidopsis photosynthesis:
The leaf chambers of photosynthesis machines are mostly designed for crops (wheat, rice, corn, soybean, cotton), and the leaves of common crops are often relatively large. Due to the different shape of the leaves, the leaf chambers of photosynthesis apparatus are commonly used to meet the needs of crops. There are rice-type leaf chambers, broad-leaf leaf chambers and round-shaped leaf chambers, which are basically suitable for all common crop leaves. The leaves of some varieties are short and grow close to the medium. Many transgenic varieties have smaller leaves. The characteristics of Arabidopsis leaves determine that the photosynthetic rate of Arabidopsis is different from that of other crops.
As a model plant, Arabidopsis thaliana has always been concerned about the determination of its photosynthetic rate by experts and professors and manufacturers of photosynthetic instruments. For this reason, the photosynthesis equipment manufacturers generally Design leaf chambers for Arabidopsis. The leaf chambers designed for Arabidopsis mainly include single leaf Arabidopsis leaf chambers and whole Arabidopsis leaf chambers. The chamber is very small 0.5-1cm2. In addition, the photosynthesis rate is greatly affected by the environment (temperature, humidity, light intensity). The relative error of the measurement will be larger. Only those who are very familiar with the photosynthesis apparatus will get more accurate data; Whole Arabidopsis thaliana leaf compartment can put a whole Arabidopsis thaliana into the leaf compartment for photosynthesis determination, which is convenient for measurement and simple to use, eliminating the influence of certain leaf growth differences on the results, but calculating the effective photosynthetic area is relatively difficult. The effective leaf area needs to be measured to correct the photosynthetic rate determined by the instrument.
Using the Arabidopsis leaf chamber equipped with a photosynthesis instrument to measure the photosynthesis of Arabidopsis leaves, in addition to the photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, and various photosynthetic response curves can be measured. The disadvantage is that the Arabidopsis leaf room is often more expensive, generally thousands of dollars and tens of thousands of dollars.
Notes on measuring the photosynthetic rate of Arabidopsis:
1 Arabidopsis is generally in the cultivation room or artificial climate box, the light intensity of the growing environment is relatively low, so if directly measured under strong light, it may produce light suppression on the leaves.
2 When determining the leaf photosynthesis of Arabidopsis thaliana leaves, attention should be paid to the selection of leaf positions.
3 Before the measurement, sufficient light adaptation should be carried out, or domestication under normal conditions should be carried out.
4 Oxygen electrode is a destructive sampling when measuring the photosynthetic rate of Arabidopsis, especially for more precious materials and when the amount of materials is relatively small
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