Chanan Itai

Effect of day length on stomatal opening and their response to phytochrome

Commelina communisplants have been usually grown in our laboratory in a 20 h light/4 h dark regime. Those conditions seemed to limit stomatal opening on epidermal strips, since data from other laboratories indicated that shorter photoperiod may decrease this restriction (e.g. McAinsh et al. 1990 and Schwartz, 1985). Moreover, stomatal response to phytochrome seems to be affected by their potential aperture (Roth-Bejerano et al. 1990). In this investigation we studied the effect of day length and phytochrome on stomatal opening.

Regulation of stomatal opening in epidermal strips of Commelina communis L. by phytochrome

Summary P fr stimulates opening. The inhibition of stomatal opening by far red light depends upon their ability to open in red light. Pretreatment of epidermis strips, in which stomata open below 2 µm, with EGTA stimulates stomatal opening in red light and increases the inhibitory effect of far red light. Lanthanum affects stomatal opening similarly to far red light. TEA and quinidine prevent stomatal opening and closure (induced by the transfer of epidermal strips with open stomata to low KC1 concentration) in red light. These channel blockers fail to affect opening and closure in the presence of far red light. It is proposed that phytochrome affects cytosolic CA 2+ concentration which in turn regulates the inward and outward K + channels.