Induced Resistance Of Tomato By Pseudomonas Fluorescens Sneb825 Against Meloidogyne Incognita

Root knot nematode is a serious threat to the production of various vegetable crops,which is one of the most difficult soil borne diseases to prevent and control in the world.Biocontrol bacteria can effectively control the number of vegetable root knot nematode population and reduce the harm.A highly effective biocontrol bacteria strain Pseudomonas fluorescens Sneb825 was screened in our laboratory for the root knot nematode disease.This study tested the control effect of P.fluorescens Sneb825 induced resistance to Meloidogyne incognita infecting tomato through pot experiment,split root experiment and greenhouse experiment,by enzyme-linked immunosorbent assay（ELISA）and real time fluorescent quantitative PCR detected the expression of reactive oxygen species in tomato roots and the content of lignin and its related genes and the change of quantity study of P.fluorescens Sneb825 induced resistance of tomato root knot nematode biocontrol effect and mechanism of action,to provide new ideas for the prevention and control of tomato nematode disease.The results are as follows:1.The pot test of Pseudomonas fluorescens Sneb825 against root knot nematode disease:by sodium hypochlorite fuchsin staining was used to observe the different time of P.fluorescens Sneb825 treatment of root irrigation and control the number of processing tomato roots in different instars of nematodes,through the split root experiment of Sneb825 on Tomato nematode resistance nematode resistance inducing effect.The results of pot experiment showed that Sneb825 treatment significantly reduced the infection of root knot nematode on tomato root in 15 dpi,J3 in root treatment J4 and the number of females was significantly lower than the control,the reduction rates were 42.4%,48.6%and 58.3%.The results of split root test showed that J3 and J4 decreased by 51.4%and 73.5%in the root system of 15 dpi fermentation broth for Sneb825 response.2.Analysis of the content of biological stress in tomato roots of active oxygen and wood:the trace analysis method and ELISA method in different time of each treatment group of hydrogen peroxide（H₂O₂）in the tomato roots content,superoxide anion radical（O₂^-）change rate and lignin content.The study found that irrigating root inoculated nematodes double treated by Sneb825 fermentation liquid,reactive oxygen species in tomato roots（10 dpi）and lignin content（5 dpi）was significantly higher than that of control,that induced tomato root knot nematode resistance in P.fluorescens Sneb825 in the process of tomato root activity and lignin content of oxygen increased significantly.3.Expression analysis of biological stress in tomato roots of active oxygen and lignin related genes by ELISA methods the ROS synthesis related gene RBOH1,peroxidase gene Ep5C and lignin synthesis related gene Tpx1 relative expression in different time points.The results show that the maximum in the expression of 10 dpi and RBOH1 the amount of Ep5C,the expression of Tpx1 in 5 dpi reached the maximum,and the gene expression analysis of the physiological and biochemical results,showed that ROS and lignin in P.fluorescens Sneb825induced resistance of tomato root knot nematode plays an important role.4.Field experiments on the control of root knot nematode by P.fluorescens Sneb825.The field height,aboveground fresh weight and dry weight,underground part fresh weight and dry weight,gall index and control effect were investigated at 25 d and 45 d after tomato transplanting.The test results showed that tomato transplanting 45 d after Sneb825 treatment to upper tomato plants plant height,fresh weight and dry weight were significantly higher than that of CK,increased by 5.6%,27.1%and 32.1%,and the gall index decreased significantly,the control effect was 38.3%and the tomato plants have significant growth in.The results show that the accumulation of reactive oxygen species and lignin is one of the defensive countermeasures to inhibit the infection of the root knot nematode by P.fluorescens Sneb825.P.fluorescens can effectively control root knot nematode disease,and has potential application prospects in agricultural production practice.