Effects Ofchitosan Oligosaccharide On The Resistant Physiologyand Biochemistryof Sugarcane

Chitosan oligosaccharide which plays an important role in the regulation ofplant growth and development, is the product of deacetylated of chitosans. Inrecent years, it has received particular attention as an elictor for inducing plantresistance. Many evidences have supported the effect of chitosan oligosaccharidein modulating plants response to several biotic and abiotic stresses. However, nostudy has been realized on sugarcane treated with chitosan oligosaccharide, so far.The experimental materials were ROC22 sugarcane. They were treated withchitosan oligosaccharide hydroponic solution of various concentrations (25mg/L,50mg/L, 75mg/L) by spraying onto leaves at room temperature. Then the contentof polyphenols and the activity of resistant-related enzymes were determined. Onekind of important pathopenesis-related protein-chitinase activity was determinedwith 3,5-dinitrosalicylic acid (DNS) method. Furthermore, the conditions had beenoptimized. At the same time, research had been done to follow the changes ofproteins in sugarcane leaves after spraying chitosan oligosaccharide solution. Theresults are shown as follows:1. The content of polyphenols more or less increased after treatment withchitosan oligosaccharide solution of 3 different concentrations. The higher theconcentration, the higher the content of polyphenols. The content of polyphenols insugarcane treated with 75mg/L chitosan oligosaccharide increased 1.8 foldcompared to the control on the first day.2. The activity of polyphenolxidase (PPO), peroxidase (POD) andphenlalanine ammonialyase (PAL) in sugrancane leaves all increased aftertreatment with chitosan oligosaccharide. But the extent of increase in leaves wasrelated to the concentration. The optimal concentration of chitosan oligosaccharideto improved POD activity was 75mg/L , which increased POD activity 2.5 times on the third day. In contrast, the 50mg/L chitosan oligosaccharide was optimum toimprove PAL and PPO activities. PAL activity increased 1.8 times on the secondday,while PPO activity reached the maxium and increased 1.8 times on the firstday with.3. The chitinase activity of sugarcane leaves was determined with DNSmethod. The reaction conditions were optimized. The results indicated that theconcentration of DNS reagent was 9.45mg·g^-1, the boiling time was 10min; theoptimum time of water bath was 1h, the temperature of reaction was 60℃, and theoptimum pH was 7.0. The 3 chitosan oligosaccharide solutions with differentconcentrations all enhanced the chitinase activity, the 50mg/L chitosanoligosaccharide solution exhibited the best result.4. The content of proteins in sugarcane leaves changed with the time underdifferent concentration of chitosan oligosaccharide treatment. The 50mg/Lconcentration of chitosan oligosaccharide influenced the content of proteinsgreatly.