Leaf Characteristics And Stomatal Opening And Closing Mechanism For The Abnormal Leaf Of Bougainvillea Spectabilis Willd

Stomata are small pores on the surfaces of leaves and generally, comprised of two guardcells. They play a critical role in plant development, plant photosynthesis and sensing thechanges of environment. Guard cells can be used as model cells for studying signal molecule.ABA (Abscisic acid) is a hormone widely distributed in plant. It can promote dormancy, inducestomatal closure, reduced plant growth and germination, regulate metabolism, enhanced stressresistance, and promote the abscission of plant organs and organ growth. H2O2and NO areimportant signaling molecules in plant. They can regulate plant growth and development,apoptosis, defense response and other physiological processes.In order to provide theory evidences for studying stomatal function, stomatal physiologyand the role of ABA in stress resistance, this study used Bougainvillea spectabilis Willd asexperimental materials to investigate the following contents:1. With the development of abnormal leaf, the changes of stomatal density, epidermal celldensity, stomatal index and guard cell length and width. The correlation between stomatalparameters.2. The effect of exogenous ABA, NO and H2O2on stomatal movement and their synergisticeffect on stomatal movement.3. The effect of different concentrations (0，50，100，300,500μM) of ABA on physiologicaland biochemical indexes of abnormal leaf.The main results are as following:1. No stomata were found in the adaxial epidermis of abnormal leaf. With the developmentof leaf, the anticlinal walls in adaxial epidermis from straight changed into sinuous; In abaxialepidermis of abnormal leaf, the epidermal cells were repand or sinuous. The stomata wereanomocytic on abnormal leaf. With the development of leaf, the stomatal density and guard cellwidth decreased; Stomatal index and guard cell length increased; The guard cells werekidney-shaped on abnormal leaf.2. Guard cell length of abnormal leaf had significant positive correlation with relative leaflength (R2=0.97**). However, a negative relationship was noted between epidermal cell densityand guard cell length, epidermal cell density and relative leaf length (R2=-0.89**). This indicated that with the development of abnormal leaf, the guard cell length increased and theepidermal cell density decreased.3. ABA (1,3,5,10μM), NO (1,3,5,10μM), H2O2(5,10,50,100μM) could inducestomatal closure dose-dependently after treated for3h. ABA-induced stomatal closure wasinhibited when NO scavenger hemoglobin (Hb) or H2O2scavenger (catalase) CAT was added.NO induced stomatal closure was inhibited by the H2O2scavenger CAT.4. After treated with different concentrations of ABA (0,50,100,300,500μM) for6h, thecontent of chlorophyll, SOD activity, soluble sugar and free proline of normal leaf increased atfirst and then decreased; the content of chlorophyll, soluble sugar, free proline and SOD activityreached maximum when treated with100μM ABA. The content of soluble protein reachedmaximum when treated with50μM ABA.