Mechanism Of Pseudomonas Induced Tomato Resistance To Root Knot Nematode

Root-knot nematodes(RKNs)are distributed all over the world.With the continuous expansion of protected areas in China,root-knot nematode disease has become a common devastating disease.Induced systemic resistance(ISR)can explore the intrinsic resistance mechanism of plants,which will be a new method of controling the plant diseases.In this paper,five bacteria strains were screened which can induce tomato resistance to Meloidogyne incognita in the field experiments,and the efficacy was verified through the pot and field experiments.At the same time,the molecular mechanism of induction of tomato resistance to RKNs by Pseudomonas putida Sneb821 was systematically studied,and the role of At SUC2 was verified using Arabidopsis thaliana mutants during nematode development.The main findings are as follows:1.Research of screening and identifing of five bacteria that can induce tomato resistance to RKNs.After field screening tests,5 strains with high efficiency were screened from 860 strains.Sneb560,Sneb815,Sneb821,Sneb825 and Sneb851 were identified as Bacillus cereus,B.subtilis,Pseudomonas putida,P.fluorescens and Serratia proteamaculans.2.Research of the efficacy of five bacteria.It was proved that 5 strains could induce tomato resistance and affect the development of RKNs in roots.At 12 dpi,5 strains could significantly affect the development of nematodes from J2 to J3;at 24 dpi;5 strains could significantly affect the development of nematodes from J3 to J4.In the pot and field experiments,all strains could increase the growth of tomatoes,and showed significantly inhibition of the number of RKNs.It is indicating that 5 strains have great potential in the prevention of nematode disease.3.Research of the transcriptome of tomato resistant to RKNs induced by Sneb821.The RNAseq technique was used to determine the different genes.The data was annotated to 53 items by GO analysis.When comparison with the KEGG database,the most significant are phenylalanine metabolism,plant hormone signal transduction,glycolysis and gluconeogenesis metabolism and starch and sucrose metabolism.These pathways and their related genes may play an important role in the induction of tomato resistance to Meloidogyne incognita by Sneb821.4.Research of the role of plant endogenous hormones in tomato resistant to RKNs induced by Sneb821.During tomato resistant to RKNs induced by Sneb821,the auxin content reached a maximum at 12 dpi,the gene expression of Sl ARF12 was up-regulated.The content of methyljasmonate was continued to increase and the gene expression of Sl JAR1 was up-regulated.The gibberellin content was significantly higher than control,and the expression of S1GA2ox5 was up-regulated at 3 dpi~12 dpi.The abscisic acid content did not changed and the gene expression of Sl PP2 C was up-regulated.The zeatin riboside content was significantly higher than control and the gene expression of Sl CKX3 is down-regulated.It shows that endogenous plant hormones and their related genes may be involved in Snbe821 induction of tomato resistance to RKNs.5.Research of soluble sugar content in tomato resistant to RKNs induced by Sneb821 and the role of At SUC2 during RKN development.The soluble sugar content and the changes of related genes were determined by HPLC and q RT-PCR.The soluble sugar content gradually increased.The up-regulation of Sl SWEET17 and Sl TMT2 may be involved in the changes of fructose content;Sl SWEET7 a and Sl TMT3 may be involved in the changes of glucose content;Sl SUT1,Sl SUT2,Sl SWEET10 a and Sl SWEET11 d may be involved in the change of sucrose content.These genes may play an important role in the induction of tomato resistance to RKNs by Sneb821.The number of RKNs did not change significantly in Atsuc2,but the development of nematode was significantly inhibited.The histochemical analysis of p At SUC2-gus revealed that GUS activity was observed at the site of nematode infection at 24 hpi after inoculation with RKNs.The At SUC2 promoter directed the expression of GUS gene at the infective site.It is suggested that At SUC2,as a specific sucrose transporter,play an important role in the early development of RKNs.