六種蕨類葉片的氣孔對藍光與二氧化碳濃度之反應

Leaf stomatal response to blue light and CO2 concentration in six fern species

黃怡清(Yi-Ching Huang)

指導教授 ： 高文媛

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.02521

摘要

葉片氣孔由成對的保衛細胞圍繞而成，是氣體進出植物體的主要通道，其形成被認為是植物適應陸生環境的一項重要演化特徵。已知被子植物葉片氣孔的開啟與關閉會受到環境因子 (例如：光與CO2濃度等) 變化影響；相較於被子植物，蕨類是較早出現於陸地的維管束植物，近來有些研究指出蕨類氣孔對藍光與CO2濃度變化的反應較不敏感。然而本實驗室先前測量發現田字草 (一種蕨類植物) 其氣孔反應類似被子植物，因此為瞭解不同蕨類間氣孔反應的差異，本研究選擇臺灣野外常見、分屬於不同演化時期以及分布在不同光環境棲地的六種蕨類 (臺灣金狗毛蕨、筆筒樹、鐵線蕨、姬書帶蕨、東方狗脊蕨、南洋山蘇)，探討他們的葉片特徵、氣孔分布與氣孔反應。
採集野外植株種植於溫室，首先測量其氣孔形態、葉片特徵與穩定性同位素分析，以及葉片在光源有無添加50 μmol m-2 s-1藍光與不同CO2濃度 (100、400、600 ppm) 時氣孔導度 (gs) 的變化，另外也比較相同物種在不同光環境生長後其葉片氣孔反應是否有差異。
測量發現這些蕨類只有下表皮有氣孔，其密度 (11.7 ~ 259.9 mm-2) 為筆筒樹 = 臺灣金狗毛蕨 > 東方狗脊蕨 > 鐵線蕨 = 姬書帶蕨 = 南洋山蘇。穩定性同位素比值顯示這六種蕨類均為C3光合作用型植物，其中南洋山蘇的長期水分使用效率最好，姬書帶蕨的效率則最差。六種蕨類葉片氣孔在飽和紅光照射之下，添加藍光不會影響其開閉 (不具有blue-light specific response)；若置於不同光環境下生長，其氣孔仍然不受藍光影響。六種蕨類葉片氣孔對於環境CO2濃度變化的反應程度可以分成三種，顯示不同物種間差異大；而同種但不同光度下生長的植株其gs在低CO2濃度 (100 ppm) 時的差異較明顯。本研究結果顯示，六種蕨類氣孔對環境CO2濃度改變的反應程度不相同，其程度大小並非依據演化的先後，物種生長棲地的差異 (例如：環境光度不同) 對該反應也有某種程度上的影響。

關鍵字

蕨類、氣孔反應、藍光、二氧化碳濃度、氣體交換

並列摘要

Stomata, pores for gas exchange between leaves and atmosphere, are surrounded by a pair of guard cells. The evolution of stomata is an important adaptation for plants to live on land. It is well known that environmental factors, such as light and CO2 concentration ([CO2]), can affect stomatal openness in angiosperms. Recently, stomata of ferns were found less sensitive to the environmental factors. However, previous studies showed that stomatal response in Marsilea crenata (a fern species) is similar to that in angiosperms. To know whether stomata of other ferns also react the same or not, I measured some leaf characteristics, stomatal distribution and stomatal response of Cibotium taiwanense, Cyathea lepifera, Adiantum capillus-veneris, Vittaria anguste-elongata, Woodwardia prolifera, Asplenium australasicum, six fern species belonging to different clades and distributed in habitats with diffent light regimes.
I transplanted field growing plants and grew them in a greenhouse. After they have established, I measured stomatal morphology and leaf characteristics of these plants and stomatal conductance (gs, a measurement of stomatal openness) when leaves were under the condition of 50 μmol m-2 s-1 blue light superimposed onto the red light and under different [CO2] (100, 400, 600 ppm). I also compared gs of the same species grown under different light intensity.
The six ferns have stomata only on abaxial surface. Stomatal density (11.7 ~ 259.9 mm-2) of leaves follows: C. lepifera = C. taiwanense > W. prolifera > A. capillus-veneris = V. anguste-elongata = A. australasicum. Stable carbon isotope analysis revealed that these six ferns are C3 plants, and A. australasicum has the highest water use efficiency while V. anguste-elongata the lowest among the six ferns. Stomata of these six ferns didn’t response further under the condition of superimposed blue light onto the red light indicating no blue-light specific response. In comparison to gs at 400 ppm of [CO2], gs of the six species showed three different degrees of change in response, which indicates that their stomata have different sensitity to changes in [CO2]. Stomatal conductance of same species grown under two light intensity have greater difference in low [CO2] (100 ppm).
In conclusion, the stomata of the six fern species showed different degree of response in three [CO2] which did not follow their evolutionary order. The light intensity of their habitats may have an effect on their stomatal response.

並列關鍵字

Fern, stomatal response, blue-light specific response, CO2 concentration, gas exchange

參考文獻

Shieh, W. C. 1994. Pteridaceae. In: T. C. Huang and Editorial committee of the Flora of Taiwan (Eds.), Flora of Taiwan, Vol. 1, 2nd edition. Editorial committee of the Flora of Taiwan, Department of Botany, National Taiwan University, Taipei, Taiwan.

Assmann, S. M. 1988. Enhancement of the stomatal response to blue light by red light, reduced intercellular concentrations of CO2, and low vapor pressure differences. Plant Physiology 87: 226-231.

Assmann, S. M., Simoncini, L., Schroeder, J. I. 1985. Blue light activates electrogenic ion pumping in guard cell protoplasts of Vicia faba. Nature 318: 285-287.

Bannister, P., Wildish, K. L. 1982. Light compensation points and specific leaf areas in some New Zealand ferns. New Zealand Journal of Botany 20: 421-424.

Bedard-Haughn, A., Van Groenigen, J. W., Van Kessel, C. 2003. Tracing 15N through landscapes: potential uses and precautions. Journal of Hydrology 272: 175-190.