Effects Of Exogenous Bacillus Amyloliquefaciens And Ralstonia Solanacearum On Tomato Root Exudates

Microbial community is an important factor affecting the function of soil ecosystem.The composition of microbial community can directly reflect the interaction of soil,plant and microorganism.Therefore,it is important to understand the functional diversity,composition and dynamic characteristics of microbial community for clarifying the various agricultural practices and useful agricultural management strategies.In this study,metabolomics research was used to analyze the root exudates from tomato.And the microbial community of tomato rhizosphere soil was analyzed by 16 S rRNA sequencing.The relationship among microbes,plants and soil microbial community was explored.The present research using the Ralstonia solanacearum RS as indicator bacteria in flat confrontation test screen one Bacillus amyloliquefaciens HZ-12.The biocontrol agent B.amyloliquefaciens HZ-12 was used against the bacterial wilt caused by R.solanacearum.The inhibitory diameter of HZ-12 to RS can be 2.22 cm.HZ-12 and RS can survive well in tomato pots.And HZ-12 can limit the growth of RS in pots test.We design the test to research the effect of HZ-12 and RS on the growth of tomato and on soil properties.We found HZ-12 effect the growth of tomato positively by measuring plant height,stem circumference,yield per plant and dry weight of plants.Compared to CK,the dry root weight of group of BA-P,RS-P and BA-RS-P increased by 11.95%,5.45% and 11.17%,respectively.Meanwhile,in compared with CK,the content of organic material in BA group(BA-S and BA-PS)increased significantly,increasing by17.00% and 13.99% respectively.In this study,we also established a study method of metabolomics for tomato root exudates analysis,including the collection and purification of samples,the derivatization of samples,the detection conditions of gas chromatography-mass spectrometry(GC-MS),and the data analysis.The root metabolites and soil metabolites of tomato were detecting by GC-MS gas chromatography-mass spectrometry GC-MS.We found that there was significant difference among CK,BA,RS and BA-RS,which is caused by the addition of Exogenous Bacillus amyloliquefaciens HZ-12 and Ralstonia solanacearum RS.In the study of the effect of exogenous addition of bacteria on tomato root exudates,it was found that two strains have no effect on the composition of tomato root exudates.And tomato root exudates mainly include organic acids,alcohols,accounting for more than 1/3 of the total secretion;followed by ketones and amines,the above four types of compounds accounted for more than 50% of the total species.However,the addition of exogenous bacterial had an effect on the relative content of root exudates,and the relative content of root exudates were more than that of CK.And it was found that the relative content of octadecanoic acid and dibutyl phthalate increased in the group of BA-P,and decreased in the group of RS-P.At the same time,we found that the content of tetradecanoic acid were lower in the group of RS-P and BA-RS-P.While 2,4-bis-Tert-butylphenol as a differential substance detected only in root exudates,the relative content was reduced in these groups,which are treated with the addition of exogenous bacteria.In the study of the effect of exogenous addition of bacteria on soil metabolites,it was found that two strains have effect on soil metabolites.It contains more organic acid than other compounds,accounting for more than 1/3 of the total secretion.At the same time,we found that the content of tetradecanoic acid and hexadecanoic acid were lower than CK in the group of RS-S、BA-RS-S and BA-S.There was significant difference among the these groups(P <0.05).Compared with BA-S and CK-S,the relative content of octadecanoic acid is higher than RS-S and BA-RS-S.To research the relationship between exogenous bacteria and soil microbial community,we found that the main soil communities were Acidobacteria,Anaerolineaceae,Nitrosomonadeceae,Nitrospira,etc.To Compared with CK group,the proportion of Acidobacteria in the BA group(BA-S and BA-P)was lower significantly(P<0.05).Acidobacteria,Anaerolineaceae,Latescibacteria,Gemmatimonadeceae,RB41,H16,Cytophagaceae and Blrii41 were significant differences among different treaments.At the same time,the presence of plant and the addition of exogenous bacteria had an effect on community composition.