title: Rapid response of leaf photosynthesis in two fern species Pteridium aquilinum and Thelypteris dentata to changes in CO2 measured by tunable diode laser absorption spectroscopy.
abstract: We investigated stomatal conductance (g(s)) and mesophyll conductance (g(m)) in response to atmospheric CO2 concentration [CO2] in two primitive land plants, the fern species Pteridium aquilinum and Thelypteris dentata, using the concurrent measurement of leaf gas exchange and carbon isotope discrimination. [CO2] was initially decreased from 400 to 200 μmol mol(-1), and then increased from 200 to 700 μmol mol(-1), and finally decreased from 700 to 400 μmol mol(-1). Analysis by tunable diode laser absorption spectroscopy (TDLAS) revealed a rapid and continuous response in g m within a few minutes. In most cases, both ferns showed rapid and significant responses of g m to changes in [CO2]. The largest changes (quote % decrease) were obtained when [CO2] was decreased from 400 to 200 μmol mol(-1). This is in contrast to angiosperms where an increase in g(m) is commonly observed at low [CO2]. Similarly, fern species observed little or no response of g(s) to changes in [CO2] whereas, a concomitant decline of g(m) and g(s) with [CO2] is often reported in angiosperms. Together, these results suggest that regulation of g(m) to [CO2] may differ between angiosperms and ferns.
authors.affiliation: The Graduate School of Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan, nishida-keisuke0725@hotmail.co.jp.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nishida
authors.forename: Naomi
authors.initials: N
authors.lastname: Kodama
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Yonemura
authors.forename: Yuko T
authors.initials: YT
authors.lastname: Hanba
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D029624:Ferns / Q000378:metabolism*; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D032498:Pteridium / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide