Analysis The Cuticular Wax And Influences Of Tissue Culture Condition On Cuticular Wax And Water Saving Of Tobacco Leaf

Plant cuticular wax covers the outer surface of aerial plant organs and tissues which isthe self-protective barrier of plant and play an important role in plant adapt to aridenvironment and a variety of biotic and abiotic stresses. Cuticular waxes mainly consist ofaliphatics and cyclic compounds, aliphatics contain very long-chain fatty acids, alkanes,alcohols, aldehydes, ketones and esters. The amount and constituents of wax are affected bymany environmental factors. The content, thickness, structure and composition characteristicsof waxes have important effect on plant drought resistance research.In our research, tobacco cultivar NC89was used as the plant material to extract thecuticular waxes. The wax composition, content and ultrastucture of wax crystals wereanalyzed by GC-MS (gas chromatography-mass spectrometry), GC-FID (gaschromatography-flame ionization detector) and SEM (scanning electron microscope). Westudied the changes of waxes load and components under tissue culture condition and theinfluences of this changes on leaf water conservation. We expected to explore a feasible wayto enhance leaf water conservation from improving cuticular wax content. The results were asfollows:1. The total content of tobacco cultivar NC89leaf cuticular waxes was5.578±0.463μg·cm-2.23chemical compounds were identified，the main components of cuticualr waxeswere alkanes, while C31alkane was dominant, with small amount of primary alcohols andtriterpenoids. N-alkanes and iso-alkanes kept odd predominance, anteiso-alkanes kept evenpredominace, and the compositions of primary alcohols and triterpenoids were rare. Cuticularwax layer on the upper and lower surface of tobacco leaf was even, smooth and withoutvisible wax crystals. They are typical smooth wax films and alkanes were the maincomposition of them.2. Tissue culture environment can affect the leaf cuticular wax load, without changingwaxy compounds and have a great influence on the content of preponderant components,especially C31alkane.The total amount of TSC (tissue-cultured seeding) cuticular wax werejust36.95%of that of control, and isoC31and anteisoC32became the dominant chemicalcompounds. Changes of alkanes content and percentage were important response of plant cuticular wax to tissue culture condition.3. Tobacco leaf water conservation was decreased under tissue culture environment.With abnormal stomatal structure, the stomatal conductance and transpiration rate of TCSleaves increased rapidly.It was difficult for plant to reduce stomatal transpiration by adjust thestomatal conductance. Under tissue culture environment, changes in wax quantity andcomponent led to changes in leaf cuticle permeability, chlorophyll leaching occurred morerapidly, leaf water loss increased significantly and water keeping ability reduced.4. Wax mixture of wheat was sprayed uniformly on tobacco leaves. Leaf surface of TCSevidently covered with mass of rodlets wax crystals like wheat and the stomatal conductanceand transpiration rate became lower. It is effective to decrease the water loss, and leaves withspraying waxes showed better water capability than normal TCS.