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A novel polysaccharide (CMP-2B) was purified from Centipeda minima by anion-exchange and gel-permeation chromatography. Structural characterization revealed that CMP-2B was a homogeneous heteropolysaccharide with an average molecular weight of 113.193 KDa. CMP-2B was made up of mannose, galacturonic acid, galactose and arabinose with a molar ratio of 0.27:0.12:0.42:0.17. The backbone chain of CMP-2B consisted of 3,6)-α-D-Manp-(1 and 4,6)-β-D-Galp-(1, and the branches were comprised of 4)-α-D-GalpA-(1, 6)-β-D-Galp-(1, T-α-L-Araf-(1 and 3)-α-L-Araf -(1. Besides, the results of antioxidant assays revealed that CMP-2B possessed signifcant free radical scavenging ability. Moreover, the results of hypoglycemic assays showed that CMP-2B displayed α-glucosidase inhibitory activities, and could significantly improve glucose consumption, glycogen synthesis and the activity of pyruvate kinase of insulin-resistance HepG2 cells. Overall, these results suggested that CMP-2B could be a new source for functional foods.

Helianthus tuberosus is well-known Asteraceae plant for its high environmental adaptation ability.It is easy to cultivate,which tempts gardeners to simply leave them completely alone to grow.However,growth and development of this plant is also sensitive to cadmium.In order to evaluate the regulation effects of brassinosteroid on plant cadmium resistance of H.tuberosus,this experiment studied the regulation effect of exogenous foliar spraying 24-brassinosteroid(24-EBL) on seedling dry weight,root shoot ratio(R/S),photosynthetic pigment content,leaf gas exchange parameters,water use efficiency(WUE),cadmium(Cd) content of two H.tuberosus varieties(NY2 and NY5) under 100 μmol/L cadmium(Cd) stress.The results showed that:(1) Compared with control,the plant dry weight,R/S ratio,photosynthetic pigment content,net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr) and WUE were decreased,while the values of intercellular CO2 concentration(Ci) were increased in NY2 and NY5 seedlings under Cd stress.(2) Compared to only Cd treatment,the plant dry weight and R/S ratio were increased to varying degrees with exogenous spraying different 24-EBL concentrations(10-10,10-9,10-8,10-7 mol/L) under Cd stress.10-9 mol/L 24-EBL(EBL2) and 10-8 mol/L 24-EBL(EBL3) treatments made the dry weight of NY2 and NY5 peaked,and 50% and 64% higher than the values of only Cd stress treatment,respectively.(3) Compared to only Cd treatment,24-EBL application increased the contents of both chlorophyll(Chl) and carotenoid(Car) in two H.tuberosus seedlings under Cd stress,and also increased their Pn,Gs,Tr in NY2.However,24-EBL decreased the values of Ci in both H.tuberosus seedlings,and Ci decrease of NY5 showed more significantly than that of NY2.(4) Under Cd stress,24-EBL increased the WUE values of NY2 and NY5 in varing degrees,respectively,and WUE increase of NY5 showed greater than that of NY2.(5) Under Cd stress,Cd accumulation in new expanded leaves of NY5 was much higher than that of NY2,and EBL2 reduced its Cd content of NY2,but EBL3 enhanced its Cd content of NY5.(6) Under Cd stress,foliar spraying 24-EBL significantly decreased Cd content in all of organs of NY2 and in root of NY5,but did not markedly affect Cd content in the other organs of NY5.Generally,the suitable concentration of 24-EBL could significantly improve cadmium resistance of H.tuberosus,and it was mainly due to improvement of photosynthesis and water use caused by 24-EBL.Furthermore,compared with NY2,the better amelioration of non-stomatal restrictions on the NY5 plant applied with 24-EBL leads to its better improvement of photosynthesis and WUE,and its higher growth stimulation under cadmium stress.The results that NY5 plants has much larger biomass,more Cd accumulation and better biomass increase applied with 24-EBL under cadmium stress than NY2 also implied that NY5 can be considered as an excellent candidate for phytoremediation of metal-contaminated soils.

The plasma membrane H+-ATPase (PM H+-ATPase) plays a key role in the activation of ion and nutrient transport, and is proposed to be involved in salt tolerance. This study investigates the acclimation of PM H+-ATPase in physic nut (Jatropha curcas L.) roots and leaves treated with 0, 50 and 200 mM NaCl for 5 days. Upon comparison with control roots, the H+-ATPase hydrolytic activity, Vmax, Km, H+-pumping activity and pH gradient potential across the plasma membrane were significantly higher in roots treated with NaCl, especially under mild salt stress. The translational activation of PM H+-ATPase of physic nut roots helped to maintain K+ and Ca2+ uptake as well as nitrogen and phosphorus uptake in roots. Compared with the control leaves, the maintenance of H+ transport under 50 mM NaCl was attributed to a modification of the lipid membrane, and the increase in H+transport under 200 mM NaCl could be because of an acid-mediated activation. Differential expression of the H+-ATPase isoforms could also occur in leaves under salt stress. Thus, the stable pH gradient created by the H+-ATPase in leaves treated with 50 mM NaCl assisted normal leaf growth. These modulations of PM H+-ATPase in the roots and leaves of physic nuts could represent a set of adaptive mechanisms to salinity. Key words: Immunoprecipitation, Jatropha curcas L., plasma membrane H+-ATPase, salt stress.