Modification Of Physiological Response To Salt Stress By Exogenous Soluble Sugars On Catharanthus Roseus

In this study,we used Catharanthus roseus as the research object in order to reveal the biological function of sucrose and trehalose with different concentration in plants and environmental interaction.Comparative study focused on depicting the phenotypic change, photosynthetic,osmotic adjustment,carbon and nitrogen metabolism in normal,salt stress and exogenous soluble sugar conditions.Catharanthus roseus seedlings have a serious stress with 250mM NaCl treatment.The direct consequence is the inhibition on plant growth,the reduction of RWC,the decrease of photosynthesis and the reduction of photosynthate.Different concentration of trehalose treatment have different shapes.ST+10mM Tre treatment increase seedlings-salt stress main stem height,root length,leaf area,LMR,LMA, biomass of shoot and root significantly.Besides light concentration trehalose treatment raise photosynthesis,chlorophyll a,b content and RWC etc.Soluble sugar(sucrose,trehalose) content free amino acids(Pro,Glu,Asp) content in seedlings also significantly increased. Judgment by morphology and photosynthesis,ST+30mM Tre treatment has a little effect to relieve salt stress,but not significant to 10mM.ST+50mM Tre treatment has no effect to salt stress.High density of trehalose has poisoning effect to Catharanthus roseus seedlings.Exogenous sucrose can relieve poisoning effect from salt stress to Catharanthus roseus seedlings in some degree.Different concentration of sucrose treatment have no different shapes. ST+100mM Suc and ST+150mM Suc treatment have same effect in the early stage. Seedlings with the treatment of ST+100mM Suc grow well in the later stage.Compared with low density of exogenous sucrose,high density can relieve decreased of biomass, photosynthesis,RWC by salt stress;increase osmotic adjustment ability.Middle,high concentration of sucrose lead to non-structural carbohydrate feedback inhibition and complex environmental effect,it may slow the growth and decrease photosynthesis of seedlings.To compare with the osmotic adjust action of Catharanthus roseus seedlings by exogenous trehalose and sucrose,ST+10mM Tre treatment has the similar results to ST+ 150mM Suc treatment,it can be explained little trehalose has same effect as multiple sucrose. It should be noted that different type and different density has different effert to help the higher plants resist salt stress.