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The effect of experimental warming on leaf functional traits, leaf structure and leaf biochemistry in Arabidopsis thaliana.

Jin B, Wang L, Wang J, Jiang KZ, Wang Y, Jiang XX, Ni CY, Wang YL, Teng NJ - BMC Plant Biol. (2011)

Bottom Line: The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming.However, a rise of 5°C produced negative effects, suggesting that lower levels of warming may benefit plants, especially those which belong to the same functional group as Arabidopsis, whereas higher levels of warming may produce negative affects.Finally, high SOD and CAT activities may enable plants grown at elevated temperatures to exhibit relatively high tolerance to temperature stress, thus alleviating the harmful effects of superoxide anion radicals and hydrogen peroxide.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Biological Sciences and Biotechnology, Yangzhou University, Yangzhou 225009, PR China.

ABSTRACT

Background: The leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered. The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming. However, such information is very important to better understand the plant responses to global warming. Therefore, we grew Arabidopsis thaliana at the three day/night temperatures of 23/18°C (ambient temperature), 25.5/20.5°C (elevated by 2.5°C) and 28/23°C (elevated by 5°C) to simulate the middle and the upper projected warming expected within the 21st century for this purpose.

Results: The 28/23°C treatment significantly reduced the life span, total biomass and total weight of seeds compared with the other two temperatures. Among the three temperature regimes, the concentrations of starch, chlorophyll, and proline were the lowest at 28/23°C, whereas the total weight of seeds, concentrations of chlorophyll and proline, stomatal density (SD), stomatal conductance (gs), net CO2 assimilation rate (A) and transpiration rate (E) were the highest at 25.5/20.5°C. Furthermore, the number of chloroplasts per cell and mitochondrial size were highest at 25.5/20.5°C and lowest at 28/23°C.

Conclusions: The conditions whereby the temperature was increased by 2.5°C were advantageous for Arabidopsis. However, a rise of 5°C produced negative effects, suggesting that lower levels of warming may benefit plants, especially those which belong to the same functional group as Arabidopsis, whereas higher levels of warming may produce negative affects. In addition, the increase in A under moderately warm conditions may be attributed to the increase in SD, chlorophyll content, and number of chloroplasts. Furthermore, starch accumulation in chloroplasts may be the main factor influencing chloroplast ultrastructure, and elevated temperature regulates plant respiration by probably affecting mitochondrial size. Finally, high SOD and CAT activities may enable plants grown at elevated temperatures to exhibit relatively high tolerance to temperature stress, thus alleviating the harmful effects of superoxide anion radicals and hydrogen peroxide.

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Transmission electron micrographs showing leaf chloroplast and mitochondrial ultrastructure of Arabidopsis grown at three temperatures. Samples were taken at ambient temperature (A and D), elevated temperature I (B, E and F), and elevated temperature II (C). Note that there were larger starch grains in the chloroplasts of A. thaliana leaves grown at ambient temperature than at elevated temperatures I and II. In addition, there were more mitochondria nearby chloroplasts at elevated temperatures I and II than at ambient temperature. St, starch grain; Mi, mitochondrion; Ch, chloroplast. Bar, 1 μm (A-F).
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Figure 3: Transmission electron micrographs showing leaf chloroplast and mitochondrial ultrastructure of Arabidopsis grown at three temperatures. Samples were taken at ambient temperature (A and D), elevated temperature I (B, E and F), and elevated temperature II (C). Note that there were larger starch grains in the chloroplasts of A. thaliana leaves grown at ambient temperature than at elevated temperatures I and II. In addition, there were more mitochondria nearby chloroplasts at elevated temperatures I and II than at ambient temperature. St, starch grain; Mi, mitochondrion; Ch, chloroplast. Bar, 1 μm (A-F).

Mentions: The size of starch grains and the ratio of total starch grains per chloroplast relative to the chloroplast profile area at ambient temperature were dramatically higher than those at elevated temperatures I and II. The average size per starch grain decreased from 1.2 μm2 at ambient temperature to approximately 0.5 μm2 at both elevated temperatures I and II (Table 1, Figure 3A-D). Starch grains accounted for an average of 15% and 13% of the chloroplast profile at elevated temperatures I and II, respectively; these values were lower than the 29% at ambient temperature (Table 1, Figure 3A-C). At ambient temperature, the starch grains took up approximately 50% of the chloroplast profile (Figure 3D). About 40% of chloroplasts lacked starch grains at elevated temperatures I and II compared to approximately 25% at ambient temperature.


The effect of experimental warming on leaf functional traits, leaf structure and leaf biochemistry in Arabidopsis thaliana.

Jin B, Wang L, Wang J, Jiang KZ, Wang Y, Jiang XX, Ni CY, Wang YL, Teng NJ - BMC Plant Biol. (2011)

Transmission electron micrographs showing leaf chloroplast and mitochondrial ultrastructure of Arabidopsis grown at three temperatures. Samples were taken at ambient temperature (A and D), elevated temperature I (B, E and F), and elevated temperature II (C). Note that there were larger starch grains in the chloroplasts of A. thaliana leaves grown at ambient temperature than at elevated temperatures I and II. In addition, there were more mitochondria nearby chloroplasts at elevated temperatures I and II than at ambient temperature. St, starch grain; Mi, mitochondrion; Ch, chloroplast. Bar, 1 μm (A-F).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3045891&req=5

Figure 3: Transmission electron micrographs showing leaf chloroplast and mitochondrial ultrastructure of Arabidopsis grown at three temperatures. Samples were taken at ambient temperature (A and D), elevated temperature I (B, E and F), and elevated temperature II (C). Note that there were larger starch grains in the chloroplasts of A. thaliana leaves grown at ambient temperature than at elevated temperatures I and II. In addition, there were more mitochondria nearby chloroplasts at elevated temperatures I and II than at ambient temperature. St, starch grain; Mi, mitochondrion; Ch, chloroplast. Bar, 1 μm (A-F).
Mentions: The size of starch grains and the ratio of total starch grains per chloroplast relative to the chloroplast profile area at ambient temperature were dramatically higher than those at elevated temperatures I and II. The average size per starch grain decreased from 1.2 μm2 at ambient temperature to approximately 0.5 μm2 at both elevated temperatures I and II (Table 1, Figure 3A-D). Starch grains accounted for an average of 15% and 13% of the chloroplast profile at elevated temperatures I and II, respectively; these values were lower than the 29% at ambient temperature (Table 1, Figure 3A-C). At ambient temperature, the starch grains took up approximately 50% of the chloroplast profile (Figure 3D). About 40% of chloroplasts lacked starch grains at elevated temperatures I and II compared to approximately 25% at ambient temperature.

Bottom Line: The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming.However, a rise of 5°C produced negative effects, suggesting that lower levels of warming may benefit plants, especially those which belong to the same functional group as Arabidopsis, whereas higher levels of warming may produce negative affects.Finally, high SOD and CAT activities may enable plants grown at elevated temperatures to exhibit relatively high tolerance to temperature stress, thus alleviating the harmful effects of superoxide anion radicals and hydrogen peroxide.

View Article: PubMed Central - HTML - PubMed

Affiliation: College of Biological Sciences and Biotechnology, Yangzhou University, Yangzhou 225009, PR China.

ABSTRACT

Background: The leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered. The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming. However, such information is very important to better understand the plant responses to global warming. Therefore, we grew Arabidopsis thaliana at the three day/night temperatures of 23/18°C (ambient temperature), 25.5/20.5°C (elevated by 2.5°C) and 28/23°C (elevated by 5°C) to simulate the middle and the upper projected warming expected within the 21st century for this purpose.

Results: The 28/23°C treatment significantly reduced the life span, total biomass and total weight of seeds compared with the other two temperatures. Among the three temperature regimes, the concentrations of starch, chlorophyll, and proline were the lowest at 28/23°C, whereas the total weight of seeds, concentrations of chlorophyll and proline, stomatal density (SD), stomatal conductance (gs), net CO2 assimilation rate (A) and transpiration rate (E) were the highest at 25.5/20.5°C. Furthermore, the number of chloroplasts per cell and mitochondrial size were highest at 25.5/20.5°C and lowest at 28/23°C.

Conclusions: The conditions whereby the temperature was increased by 2.5°C were advantageous for Arabidopsis. However, a rise of 5°C produced negative effects, suggesting that lower levels of warming may benefit plants, especially those which belong to the same functional group as Arabidopsis, whereas higher levels of warming may produce negative affects. In addition, the increase in A under moderately warm conditions may be attributed to the increase in SD, chlorophyll content, and number of chloroplasts. Furthermore, starch accumulation in chloroplasts may be the main factor influencing chloroplast ultrastructure, and elevated temperature regulates plant respiration by probably affecting mitochondrial size. Finally, high SOD and CAT activities may enable plants grown at elevated temperatures to exhibit relatively high tolerance to temperature stress, thus alleviating the harmful effects of superoxide anion radicals and hydrogen peroxide.

Show MeSH
Related in: MedlinePlus