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High-susceptibility of photosynthesis to photoinhibition in the tropical plant Ficus microcarpa L. f. cv. Golden Leaves.

Takahashi S, Tamashiro A, Sakihama Y, Yamamoto Y, Kawamitsu Y, Yamasaki H - BMC Plant Biol. (2002)

Bottom Line: We compared the response of photosynthetic activities to strong light between GL and its wild-type (WT, Ficus microcarpa L. f.).In contrast, WT did not show any substantial changes of Fv/Fm values throughout the day (between 0.82 and 0.78).We conclude that the photosynthetic apparatus of GL is more highly susceptible to photoinhibition than that of WT.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Cell and Functional Biology, Faculty of Science, University of the Ryukyus, Okinawa, Japan. takahashishunichi@hotmail.com

ABSTRACT

Background: The tropical plant Ficus microcarpa L. f. cv. Golden Leaves (GL) is a high-light sensitive tropical fig tree in which sun-leaves are yellow and shade-leaves are green. We compared the response of photosynthetic activities to strong light between GL and its wild-type (WT, Ficus microcarpa L. f.).

Results: Field measurements of maximum photosystem II (PSII) efficiency (Fv/Fm) of intact sun-leaves in GL showed that photo synthetic activity was severely photoinhibited during the daytime (Fv/Fm = 0.46) and subsequently recovered in the evening (Fv/Fm = 0.76). In contrast, WT did not show any substantial changes of Fv/Fm values throughout the day (between 0.82 and 0.78). Light dependency of the CO2 assimilation rate in detached shade-leaves of GL showed a response similar to that in WT, suggesting no substantial difference in photosynthetic performance between them. Several indicators of photoinhibition, including declines in PSII reaction center protein (D1) content, Fv/Fm value, and O2 evolution and CO2 assimilation rates, all indicated that GL is much more susceptible to photoinhibition than WT. Kinetics of PAM chlorophyll a fluorescence revealed that nonphotochemical quenching (NPQ) capacity of GL was lower than that of WT.

Conclusion: We conclude that the photosynthetic apparatus of GL is more highly susceptible to photoinhibition than that of WT.

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Light-response curves for the rate of photosynthetic CO2 assimilation in WT and GL. Shade-leaves, which exhibited identical green coloration in both WT and GL, were used for measurements. Light intensities of irradiation were changed from high to low. (•, blue), WT; (Δ, red), GL. Points are the means of three (•) or four (Δ) separate measurements ± SD.
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Figure 3: Light-response curves for the rate of photosynthetic CO2 assimilation in WT and GL. Shade-leaves, which exhibited identical green coloration in both WT and GL, were used for measurements. Light intensities of irradiation were changed from high to low. (•, blue), WT; (Δ, red), GL. Points are the means of three (•) or four (Δ) separate measurements ± SD.

Mentions: We compared photosynthetic performance between GL and WT to confirm that the fundamental photosynthetic machinery of GL is normal. Shade-leaves of GL and WT, both of which are green, were used for this purpose. Figure 3 shows the light response curves of CO2 assimilation rate (based on surface area) in detached shade-leaves. The chlorophyll content of shade-leaves in GL (green) was 0.58 g Chl m-2 and that in WT (green) was 0.70 g Chl m-2. GL showed a very similar light-response curve to WT and there was no substantial difference in the maximum activity of CO2 assimilation between them. These results clearly demonstrate that the photosynthetic capacity of GL is almost identical to that of WT, suggesting that photosynthetic machinery of GL is functionally not defective.


High-susceptibility of photosynthesis to photoinhibition in the tropical plant Ficus microcarpa L. f. cv. Golden Leaves.

Takahashi S, Tamashiro A, Sakihama Y, Yamamoto Y, Kawamitsu Y, Yamasaki H - BMC Plant Biol. (2002)

Light-response curves for the rate of photosynthetic CO2 assimilation in WT and GL. Shade-leaves, which exhibited identical green coloration in both WT and GL, were used for measurements. Light intensities of irradiation were changed from high to low. (•, blue), WT; (Δ, red), GL. Points are the means of three (•) or four (Δ) separate measurements ± SD.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC102767&req=5

Figure 3: Light-response curves for the rate of photosynthetic CO2 assimilation in WT and GL. Shade-leaves, which exhibited identical green coloration in both WT and GL, were used for measurements. Light intensities of irradiation were changed from high to low. (•, blue), WT; (Δ, red), GL. Points are the means of three (•) or four (Δ) separate measurements ± SD.
Mentions: We compared photosynthetic performance between GL and WT to confirm that the fundamental photosynthetic machinery of GL is normal. Shade-leaves of GL and WT, both of which are green, were used for this purpose. Figure 3 shows the light response curves of CO2 assimilation rate (based on surface area) in detached shade-leaves. The chlorophyll content of shade-leaves in GL (green) was 0.58 g Chl m-2 and that in WT (green) was 0.70 g Chl m-2. GL showed a very similar light-response curve to WT and there was no substantial difference in the maximum activity of CO2 assimilation between them. These results clearly demonstrate that the photosynthetic capacity of GL is almost identical to that of WT, suggesting that photosynthetic machinery of GL is functionally not defective.

Bottom Line: We compared the response of photosynthetic activities to strong light between GL and its wild-type (WT, Ficus microcarpa L. f.).In contrast, WT did not show any substantial changes of Fv/Fm values throughout the day (between 0.82 and 0.78).We conclude that the photosynthetic apparatus of GL is more highly susceptible to photoinhibition than that of WT.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Cell and Functional Biology, Faculty of Science, University of the Ryukyus, Okinawa, Japan. takahashishunichi@hotmail.com

ABSTRACT

Background: The tropical plant Ficus microcarpa L. f. cv. Golden Leaves (GL) is a high-light sensitive tropical fig tree in which sun-leaves are yellow and shade-leaves are green. We compared the response of photosynthetic activities to strong light between GL and its wild-type (WT, Ficus microcarpa L. f.).

Results: Field measurements of maximum photosystem II (PSII) efficiency (Fv/Fm) of intact sun-leaves in GL showed that photo synthetic activity was severely photoinhibited during the daytime (Fv/Fm = 0.46) and subsequently recovered in the evening (Fv/Fm = 0.76). In contrast, WT did not show any substantial changes of Fv/Fm values throughout the day (between 0.82 and 0.78). Light dependency of the CO2 assimilation rate in detached shade-leaves of GL showed a response similar to that in WT, suggesting no substantial difference in photosynthetic performance between them. Several indicators of photoinhibition, including declines in PSII reaction center protein (D1) content, Fv/Fm value, and O2 evolution and CO2 assimilation rates, all indicated that GL is much more susceptible to photoinhibition than WT. Kinetics of PAM chlorophyll a fluorescence revealed that nonphotochemical quenching (NPQ) capacity of GL was lower than that of WT.

Conclusion: We conclude that the photosynthetic apparatus of GL is more highly susceptible to photoinhibition than that of WT.

Show MeSH
Related in: MedlinePlus