Research Of DIMBOA Content And PAL Activity In Different Resistant Maize Varieties

In this research an important secondary metabolites-DIMBOA in maize was extracted and identified,and the chromatography method of detecting DIMBOA content was optimized.On the basis of the results,DIMBOA content in 7-day-old etiolated seedling of 46 maize varieties were quantitative analysed.Furthermore,eight maize varieties were selected for field testing,in order to detect the changes of DIMBOA content and the activity of PAL in leaves during different growth duration,mean while the difference of DIMBOA content between 7-day-old etiolated seedling and 7-day-old normal seedlings was analyesed.The main results were summarized as follows:1.Some pink needle-like crystals were extracted and purified from 7-day-old etiolated seedlings Zhengda 619 maize variety,Identified with the methods of melting point,UV,HPLC and HPLC-MS,the data was the same as literature,it showed that the crystals was DIMBOA,Its molecular weight was 211. 2.Optimized the chromatographic method of detecting DIMBOA content in maize sample.The chromatographic method of detecting DIMBOA content in 7-day-old etiolated seedlings was:column:WatersXTerra ^TMRp C₁₈, 250mm×4.6mm,5μm;column temperature:30℃;mobile phase:methanol: acetic acid solution=28%:72%(pH=2.6);The flow rate was 1ml/min; detecting wavelength 280nm;injected sample quantity 10μl.The chromatographic method of detecting DIMBOA content in 7-day-old normal seedlings was:column:WatersXTerra ^TMRP C₁₈,250mm×4.6mm,5μm; column temperature:30℃;mobile phase:methanol:acetic acid solution=25%: 75%(pH=2.6);The flow rate was 1ml/min;detecting wavelength 280nm; injected sample quantity 10μl。3.The results of quantitative detect showed that,all tested maize varieties' 7-day-old etiolated seedlings contained DIMBOA,but the content was significantly different among different maize varieties.Among them the zhengda 619s' DIMBOA content was the highest,the Guiyu 505s' DIMBOA content was the least.DIMBOA content in tested sweet waxy corn's was relatively lower than the content in most of normal maize varieties.4.During different growth duration,the DIMBOA content and PAL activity in the first leaf from top,third leaf from top and ear leaf were detected separately.It showed that all tested maize varieties' DIMBOA content decreased simultaneously with the increase of growth duration both in first leaf from top and third leaf from top,meanwhile the PAL activity increased with the increase of growth duration both in first leaf from top and third leaf from top.In ear leafves,there were two kinds of changes about the DIMBOA content,in 5 varieties the DIMBOA content decreased with the increase of growth duration,another 3 varieties' DIMBOA content decreased afert increase.The PAL activity changed in two trends,one was increased continuancely with the increase of growth duration,another one was decreased afert increase.It can be concluded that in the reproductive period the changes of DIMBOA content and PAL activity in maize leaves were contrary.