| Efficient foreign substances could improve salt tolerance in plants. That was very meaningfulfor increasing grain yields and utilizing of saline-alkali land efficiently. Many study resultsshowed that sulfated polysaccharides from Enteromorpha prolifera was a kind of bioactivesubstances, however there were little work in the literature is related to the agricultural uses ofthem. We obtained sulfated polysaccharides from E. prolifera with different molecular weights bymicrowave-assistance. Using some physiological and biochemical methods, we estimated theefforts of sulfated polysaccharides from E. prolifera on salt tolerance of plants and wanted toinvestigate the related mechanism. Our studies not only had significant meaning to improve thesalt tolerance in plants with foreign substances but also gave a way for potential use of ‘green tideseaweed’. The conclusions are as below:1. The chemical compositions showed EP was a kind of heteropolysaccharide with huge Mwand the content of total sugar was52.83%. The contents of sulfate and uronic acid in sulfatedpolysaccharide from E. prolifera (EP) were respectively21.98%and26.46%. The majorproportions of monosaccharide were rhamnose and glucose (almost1:1) and there were also smallamounts of xylose, mannose and galactose and trace amounts of fucose. The characteristicabsorption of EP in the FT-IR suggested that typical absorptions at842,1248and1642cm-1werecontributed to the stretching vibration of C-O-S, S=O and C=O respectively. A method wasestablished to degrade EP with microwave-assistance acid hydrolysis and prepared EPs withdifferent Mws. DEP-1、DEP-2and DEP-3were prepared and their Mws were234KDa,19.1KDaand5.1KDa respectively. Analysis of chemical compositions and FT-IR spectra indicated that thecontents of sulfate and uronic acid in DEP-1、DEP-2and DEP-3were similar to EP. The resultindicated that only glycosidic linkages were cleft psecially and the significant structural units inEP were not broken. 2. We investigated the influences of EP on maize and wheat under slat stress and the resultshowed:1mg/mL EP could increase plant and rootstock height both in maize and wheat under100mmol/L NaCl stress. The contents of MDA and the membrane pemeability decreased.Compared to NaCl stress, the SOD, CAT, POD and APX activity were stimulated to higher levelsunder both EP and NaCl treatment. Those free radical scavenging enzymes could avoid thedamage by accumulation of reactive oxygen species in maize and wheat. Also the degradation ofchlorophyll was declined which implied the using of EP could protect chloroplast functions andsustain photosynthesis under salt stress.3. We also studied the changes of salt tolerance in maize and wheat after being treated withdifferent Mws samples:1mg/L DEP-1, DEP-2and DEP-3could increase more plant and rootstockheight than EP both in maize and wheat under100mmol/L NaCl stress. We got the same result onbiomass accumulation. We investigated chlorophyll a fluorescence transient and some importantparameters such as Wk%, φPoand PI. Results showed that EP, DEP-1, DEP-2and DEP-3couldprotect PSⅡ from severely damage and keep photosynthetic apparatus maintain normal functionunder slat stress. It also implied that the possible mechanism may relate to alleviating effect onphotoinhibition.4. EP, DEP-1, DEP-2and DEP-3with concentrations of0.2mg/mL,1mg/mL or5mg/mLcould improve salt tolerance in arabidopsis thaliana while the samples of1mg/mL had moresignificant effort. Compared to EP, DEP-1and DEP-3had better efforts under the sameconcentration. The plants showed upregulation of SOS1and rd29A after treated with1mg/mL EP,DEP-1, DEP-2, and DEP-3by RT-PCR. Compared to CK, SOS1upregulated to1.23and1.22times after treated with DEP-1and DEP-3, while rd29A upregulated to5.6and2.5timesrespectively. Results showed that DEP-1and DEP-3increased salt tolerance well in Arabidopsisthaliana. We concluded that the EPs could increase intracellular compartmentation of Na+andosmotic adjustment to improve slat tolerance in arabidopsis thaliana. |
PDF Full Text Request