Metabonomics Study On Soybean Treated With Extracellular Polysaccharides And Secreted Proteins Of Phytophthora Sojae

Soybean blight caused by Phytophthora sojae is one of the most important diseases affecting soybean yield and quality in soybean production.As early as a decade ago,the annual economic losses caused by the disease in the world were nearly billions of dollars.With the genetic variation of P.sojae,the incidence of P.sojae has become more obvious in recent years.So it is very important to study the pathogenesis of P.sojae.In the process of soybean infection by P.sojae,it secretes polysaccharides and proteins just like the pioneer troops of the army.Therefore,the study on the physiological and biochemical effects of crude extracellular polysaccharides and secreted proteins of P.sojae on soybean provides experimental basis for studying the pathogenic mechanism of P.sojae.In this paper,P.sojae strain GY8-3 was used as material to extract crude extracellular polysaccharides and secreted proteins to treat soybean callus.The effects of crude polysaccharides and secretory proteins on soybean metabolism were evaluated by RT-PCR and GC-MS.The results showed that the content of NO and reactive oxygen species in the treatment group of exopolysaccharide and its secreted protein of P.sojae was significantly higher than that in the control group.Among the 10 resistance related genes in EPS treatment group,6 genes were significantly up-regulated six hours after the treatment,and 4 genes were up-regulated in secretory proteins treatment group.There were 58 metabolites identified by GC-MS,of which more than 20 metabolites were significantly changed in EPS treatment group(P<=0.05,VIP>1);for example,the relative contents of glucoside and proline(log2(T/C))increased 2.51 times,mannose 2.19 times,succinic acid 1.22 times;the relative contents of valine,asparagine and threonine decreased 2.16 times and 1.16 times,respectively.Propionic acid,terpinol and inositol decreased by 0.91,0.75 and 0.54 times,respectively.There were more than 30 metabolites in the secretory proteins treatment group.For example,the relative content of glucoside increased 4.77 times and mannose increased 2.71 times,both of which were higher than that in the extracellular crude polysaccharide treatment group,proline increased 2.5 times,which was similar to that in the extracellular crude polysaccharide treatment group,while the relative content of valine and asparagine did not cliange significantly.In a word,the metabolism of soybean in different treatments changed after the treatment of soybean with crude extracellular polysaccharide and its secreted protein of P.sojae.The similarity between them is that both of them improve soybean systemic resistance and induce soybean to respond to their stimuli by weakening glycolysis pathway,increasing the contents of glucoside,proline and cadaverine in vivo.The difference is that the crude polysaccharide of P.sojae can weaken the nitrogen metabolism pathway of soybean and enhance the tricarboxylic acid cycle of soybean.Ring affects the growth and development of soybean.Based on the study of metabolomics,this experiment revealed the difference of soybean metabolism under the treatment of extracellular crude polysaccharide and its secreted protein of P.sojae GY8-3 strain.It provided theoretical basis for studying the mechanism of action of these two substances during the infection of R sojae on soybean,and also provided new research ideas and methods for studying the pathogenic mechanism of P.sojae.At the same timIdentification e,it also has certain reference significance for studying the metabolic changes of soybean under external stimulation.