The Epidermal Morphology And Stomatal Movemental Mechanism For The Flower Of Caesalpiniaceae Bauhinia L.

Stoma is the important channel to exchange gas and water between plants and theexternal environment. In general, stoma is consisted of two guard cells.In order to lay the foundation for revealing the mechanism of how stomata on floralorgans of Caesalpiniaceae Bauhinia were effected by exogenous signal materials,flowers of Caesalpiniaceae Bauhinia L. were studied as a material in the presentresearch. The flowers of Caesalpiniaceae Bauhinia were classified into6developmental stages basing on different length of petal. The epidermal morphology,epidermal cell density and stomatal density of flowers were investigated at each stageby light microscopy. ABA, NO, H₂O₂and their scavenger (catalase CAT, hemoglobinHb) were also used to treat epidermal stomata on the flowers of CaesalpiniaceaeBauhinia. The physiological changes mechanism of stomatal movement wereobserved. The change law about epidermal stomatal density on different floral organs,the effect of inducing stomatal closure by ABA, NO, H₂O₂and the relationshipbetween these three exogenous signal materials were discussed. The main conclusionsare as follows:1. Stomata were on the surface of sepal, petal, style and anther, but not filaments orovary. Anomocytic, paracytic, and actinocytic stomatal complexes were distributed onflower organs. However, ontogenetic changes in stomatal complexes variedconsiderably among flower organs.2. Epidermal cells were polygonal with straight anticlinal walls on the uppersurface of sepal, upper surface of petal, style, anther, ovary and filaments. Butepidermal cells of lower surface of petal were irregular with repand anticlinalwalls.3. Epidermal cell density on the surface of sepal, petal, style, anther, ovary andfilaments decreased with flower development, which suggests that the growth of sepal,petal, style, anther, ovary and filaments were mainly due to cell expansion. At thesame stage, stomatal density of upper surface of petal were greater than lower surface of petal (P<0.05). Stomatal density was decreasing on surface of sepal and petalduring the development of flower. There were some stomatal clusters on the petal.Some stomatal clusters were consisted of2or3adjacent stomata. But these stomatalclusters were rare on floral epidermis of Caesalpiniaceae Bauhinia.4. ABA, NO and H₂O₂could induce stomatal closure dose-and time-dependently(P<0.05) in the10,100,500and1000μmol.L-1concentration range. With theconcentration and treatment time of the ABA, NO and H₂O₂are increasing gradually,the role of induction epidermal stomatal closure of petals is more obvious.5. The mixture of any two of ABA, NO and H₂O₂were used to treat upper and lowerepidermal stomata on petal of Caesalpiniaceae Bauhinia. The results show that thetreatment effect of the mixed solution were greater than those of the individualprocessing. But effect of inducing stomatal closure by the mixed processing of ABA,NO, H₂O₂with scavenger Hb,CAT was weakened than those of the individual andmixed processing. This shows that there is a synergistic effect among ABA, NO andH₂O₂in inducing stomatal closure.