The Effect Of Different Microorganisms On Crop Root Exudate

Root exudate was an important carrier in plants for the exchange of substances,energy and information with environment.Root exudate and rhizospheric microorganisms mutually affect each other,together they constituted the plant-microorganism symbiotic system.Previous studies revealed that root exudate was highly related to plant diseases.On one hand,a large number of substances was secreted into growing media by plant root and these substances may utilized by certain microorganisms asnutrient sources.On the other hand,rhizospheric microorganisms could also produce some resistant substances which could assist the plant combating certain disease.The metabolites produced by Bacillus amyloliquefaciens could induced the defenses mechanism of the plant,and inhibited the growth of pathogen.Based on this,we studied the variation of root exudates after the inoculation of different microorganisms to tobacco,tomato,pepper and corn.The results provided the theoretical basis for the combating method of bacterial wilt,blackleg and brown spot disease.In this study,tobacco,tomato,pepper and corn were selected,and Ralstonia solanacearum and its antagonistic bacteria Bacillus amyloliquefaciens YH-22,Phytophtora parasitica and its antagonistic bacteria Bacillus amyloliquefaciens infected soil 1,Alternaria logiperand its antagonistic bacteria Bacillus amyloliquefaciens Xa 1 were inoculated to the four plants.Afterward,the content change and variety change of root exudates were measured by GC-MS.The results were as follows:The main chemical components of the root exudates of four plants wereamines,alcohols,organic acids,alkanes,sugars and lipids.The root exudates variation trend of tobacco,tomato and pepper(these three plants belonged to solanaceous)were similar,while the root exudates variety of corn was significantly richer than other plants.In addition,the organic acids account for the majority in corn root exudates.After the inoculation of Ralstonia solanacearum and its antagonistic bacteria Bacillus amyloliquefaciens YH-22,Phytophtora parasitica and its antagonistic bacteria Bacillus amyloliquefaciens infected soil 1,Alternaria logiperand its antagonistic bacteria Bacillus amyloliquefaciens Xa 1 to tobacco,tomato,pepper and corn,the respective root exudates were measured and analyzed.From the results,the relative amountof allelochemical such as benzoic acid,dibutyl isophthalate,isophthalic acid and di(2-flurorophenyl)ester siginificantly decreased after the inoculation of antagonistic bacteria in tobacco,tomato and pepper group.While in corn group,the content of these substances hardly changed.These results clearly indicated that such allelochemical have chemotaxis effect on pathogen in rhizosphere of solanaceous plants.Without the inoculation of the strains,no sugers were detected in any of the plant root exudates.After the inoculation of antagonistic bacteria or pathogen,however,sugers were detected in root exudates.Moreover,the sugers content in root exudates after the inoculation of antagonistic bacteria was significantly higher than that of the inoculation of pathogen,which demonstrated that the inoculation of Bacillus amyloliquefaciens could stimulate the root to secrete sugars.