Stomatal blue light response is present in Marsilea crenata, an amphibious fern

Stomatal blue light response is present in Marsilea crenata, an amphibious fern

The active and passive regulation of stomatal response to environmental stimulation has been well studied in angiosperms but rarely in ferns. Active stomatal control of Marsilea crenata, an amphibious fern, in response to CO2 concentration and exogenous application of abscisic acid was reported in a previous study. The objectives of the current study were to investigate whether M. crenata has stomatal blue light (BL) response and to evaluate the sensitivity of the response. Leaf stomatal conductance (gs) of the fern grown under two light regimes and the apertures of stomata on isolated epidermal strips irradiated with photosynthetically saturated red light (RL) or with RL plus BL were measured. Stomatal response of two angiosperms and two other ferns (Adiantum capillus-veneris and Nephrolepis auriculata) were also measured. Application of 50μmol m-2 s-1 BL caused a significant increase in gs of M. crenata and Sambucus chinensis (an angiosperm) leaves irradiated with photosynthetically saturated RL of 900μmol m-2 s-1, indicating the presence of stomatal BL-specific response. The response was not detected in the two other ferns. In comparison to sole RL irradiated epidermal strips, a 43 % increment of the ratio of stomatal width/length was measured in M. crenata epidermal strips irradiated with RL plus BL. M. crenata grown under shading lost the stomatal BL-specific response. In conclusion, this is the first report of the presence of stomatal BL-specific response in a fern of Polypodiopsida. However, growth conditions have strong effects on the sensitivity of the specific response of the fern.