Promotive Effects Of 5-Aminolevulinic Acid (5-ALA) On Stomatal Opening And Its Mechanism

Stomatal movement is stomatal opening and closing. It is mainly composed by stomatal guard cells regulating the exchange of CO2 and O2, and therefore controlling leaf photosynthetic efficiency and water loss through transpiration. Therefore, a necessary condition is between stomatal opening and CO2 into the smooth conduct photosynthesis, stomatal aperture any influence factors are likely to affect net photosynthetic rate. In this paper, Arabidopsis, apple leaves were used to study the effects of exogenous 5-ALA to defend the movement of cells from the epidermis and the mechanism under leaves, in order to investigate the mechanism of 5-ALA regulation of stomatal aperture. The main results are as follows:1. The effects for 5-aminolevulinic acid (5-ALA) to promote stomatal aperture was studied in the work with leaves of Arabidopsis combined with pharmacology, microscopy and laser-scanning confocal microscopy. It was found that 5-ALA promoted stomatal opening under both light and dark conditions. It also inhibited the stomatal closure induced by exogenous ABA. While excessive synthesis of 5-ALA transgenic plants PO and P3 can be suppressed exogenous ABA-induced stomatal closure.5-ALA treatment also exists concentration effect, while the treatment with 0.5 mg·L-1 5-ALA can more effectively promote stomatal opening in the light and dark.2. The effects for 5-aminolevulinic acid (5-ALA) to promote stomatal aperture was studied in the work with abaxial epidermis of detached leaves of Arabidopsis combined with pharmacology, microscopy and laser-scanning confocal microscopy. It was found that 5-ALA inhibited the stomatal closure induced by exogenous ABA and H2O2.and reversed the closure by dark and Ca2+.5-ALA treatment was found to reduce the endogenous H2O2 and Ca2+ content in guard cells of Arabidopsis leaves. Therefore, it can be deduced that 5-ALA-induced stomatal opening may be the result of down-regulation of H2O2 and Ca2+ content in the guard cells.3. A possible mechanism for 5-aminolevulinic acid (5-ALA) to promote stomatal aperture was studied in the work with abaxial epidermis of detached leaves of apple (Malus domenstica Korkh. cv. Fuji) combined with pharmacology, microscopy and laser-scanning confocal microscopy. It was found that 5-ALA promoted stomatal opening under both light and dark conditions. It also inhibited the stomatal closure induced by exogenous ABA and H2O2, and reversed the closure by Ca2+. Furthermore,5-ALA treatment was found to reduce the endogenous H2O2 and Ca2+ content in guard cells of apple leaves. Therefore, it can be deduced that 5-ALA-induced stomatal opening may be the result of down-regulation of H2O2 and Ca2+ content in the guard cells of apple leaves.