The Epidermal Morphology And Stomatal Movemental Mechanism Of Erythrina Corallodendron Flower

ObjectiveGuard cells determine the extent of stomatal aperture, and then regulate water loss through transpiration and CO2 uptake for photosynthesis by sensing environmental conditions. Via stomata, flowers can undergo non-foliar photosynthesis, which is mainly affected by stomatal density. Pollens are released from anthers, and the dehiscence of anther is caused by dehydration of anther wall. Therefore, this study was mainly designed to investigate the following:1. Stomatal density and photosynthesis of Erythrina corallodendron flower organs.2. Whether stomata in the adaxial and the abaxial epidermis of sepals underwent the same function of sensing environmental conditions.3. The relationship between anther stomata and dehiscence of anther.Methods1. The epidermal morphology, epidermal cell density, stomatal density, guard cell length and width of flowers at each stage were investigated by light microscopy. Photosynthesis of flower organs was also measured.2. The influence of exogenous abscisic acid (ABA) on stomatal aperture of the adaxial and the abaxial epidermis of sepals and anthers were studied.3. The movement mechanism of these stomata by plasmolysis and fluorescence experiments was further investigated.Results1. Stomata were on the surface of sepal, vexilla, keel, anther, gynophore, ovary, and style but not wing or filaments. Flower organs showed anomocytic, paracytic, and actinocytic stomatal complexes. However, ontogenetic changes in stomatal complexes varied considerably among flower organs. Epidermal cell density on the surface of sepal, vexilla, keel, wing and filaments decreased with flower development, which suggests that the growth of sepal, vexilla, keel, wing and filaments were mainly due to cell expansion. Stomatal density of most flower organs, such as sepal, vexilla, keel, gynophore, and ovary, did not change markedly at later developmental stages. Changes in guard cell length and width varied considerably among different organs during flower development. Unlike the leaves, vexilla did not undergo photosynthesis.2. Stomata in the abaxial epidermis of sepals were induced to close by abscisic acid (ABA), while stomata in the adaxial epidermis of sepals and anthers did not close in response to exogenous ABA. In the adaxial epidermis of sepals and anthers, stomata did not close even when guard cell's turgor was reduced to zero by plasmo lysis, while stomata in the abaxial epidermis of sepals closed and had plasmolysis by sucrose solution.3. Stomata in the adaxial and adaxial epidermis of sepals and anthers were fluorescent under fluorescence miroscope, suggesting that protoplasts of guard cells were alive.Conclusion:1. Ontogenetic changes in stomatal distributions and complexes varied considerably among flower organs. Changes in guard cell length and width varied considerably among different organs during flower development.2. Guard cells in the adaxial and the abaxial epidermis of these sepals underwent the different function of sensing environmental conditions, and the cause of the failure of guard cells in the adaxial epidermis to sense environmental conditions may lie mainly in the lack of guard cell wall elasticity.3. The cause for the failure of anther stomata to close may lie mainly in the less elasticity of guard cells wall. And these continuously open stomata on anther may be accelerating dehiscence of anther.