Effects Of Exogenous Nitric Oxide, Hydrogen Peroxide And Abscisic Acid On Stomatal Movement In The Corolla, Bulb Scale And Leaf Of Zephyranthes Candida

Stomata are pores in the aerial plant epidermis surrounded by two guard cells, which control the aperture open and close. Stomata are specialized epidermal structures that regulate CO2, O2 and water vapor exchange between plants and their environment.The epidermis of flowers, scape, bulb, leaves, fruits, seeds and roots of Zephyranthes candida plants were investigated under light microscope. The stomatal index, stomatal density, guard cell length and width of the upper and lower petal surface, epidermis of scape, exocarp and adaxial and abaxial leaf epidermis were compared. The relevances between stomatal density and guard cell area on the petal and leaf were analyzed respectively. Using the lower surface of corolla, outer surface of bulb scale and abaxial epidermis of leaf of Zephyranthes candida as the experimental material, the effect of exogenous NO, H2O2 and ABA with different concentrations on their stomatal movement and their correlation were studied. This study has been designed to obtain knowledge on stomatal distribution and movement in the different organs, which can supply with some new morphological information and reveal the impact mechanism on stomatal movement under the exogenous hormone and signal molecule in the different organs of Z. candida. The main results are as follows:1. There are stomata in the surface of petal, stamen, pistil, ovary, peduncle, scape, bulb scale, fruit and seed besides the conventional parts such as leaves and stems. But the stomata are absent from the root.2. The stomatal index and stomatal density on the adaxial leaf epidermis are significantly greater than on the abaxial (P<0.05). The stomatal index and stomatal density on the scape and leaf are significantly greater than on the petal and fruit (P<0.05). The stomatal index and stomatal density reach minimum on the exocarp. The guard cell area is largest on the abaxial leaf epidermis (P<0.01), but smallest on the lower petal surface (P<0.01). There is no significant correlation between the stomatal density and guard cell area on the petal (y=0.089, P>0.05). An extremely significant negative correlation is observed between the stomatal density and guard cell area on the leaf (γ=-0.535, P<0.01).3. NO, H2O2 and ABA could induce various degrees of stomatal closure in dose-dependently.4. The effects of the mixed solution of NO, H2O2 or ABA were greater than those of the individual processing. NO scavenger Hb and H2O2 scavenger CAT could weaken the effect of NO, H2O2 or ABA significantly. This showed that the stomatal closure could be co-induced by NO,H2O2 and ABA.5. NO, H2O2 and ABA could induce the stomatal closure in the corolla, bulb scale and leaf of Z. candida. This showed that reproductive organ (flower), below ground organ (bulb) and above-ground vegetative organ (leaf) were of unity. While NO, H2O2 and ABA could induce various degrees of stomatal closure in the different organs, which showed that there was difference from the different organs.