Study On The Interaction Mechanisms Between Paenibacillus Polymyxa SC2 And Pepper

Paenibacsillus polymyxs SC2 is a plant growth promoting rhizobacteria isolated from the rhizosphere of pepper.The strain has a wide variety of antibacterial spectrum.In order to further study the mechanism of interaction between P.polymyxa SC2 and pepper,pot experiments with the new crop soil and continuous cropping soil for pepper growth promoting effect of P.polymyxa SC2 in greenhouse conditions,combined with the sterile environment of pepper and SC2 interaction transcriptome to explore the interaction mechanism.In the new crop soil pot experiment found that SC2 could effectively promote the growth of pepper,and the stem diameter of the treated group was significantly higher than that of the control group at 30 days and 40 days(P<0.05),5.26%and 5.7%crude.The significant difference(P<0.01)was reached at 50 days after treatment,which was more than that of the control group(6.52%).The leaf length and leaf width were larger than those of the control group at 40 days,and the leaf length was significantly different from CK control group(P<0.05).The chlorophyll content of SC2 treated group was significantly higher than that of control group.The content of urease in the treatment group was 19.4%higher than that in CK group(P<0.01),and the content of sucrase was significantly higher than that of CK group(P<0.05).In the continuous cropping soil test the survival rate of pepper in SC2 group was higher than that in CK group.At the time of 10 days,20 days and 30 days the SC2 groups were significantly higher than those in the control group(P<0.05),and increased by 18.3%,9.8%and 8.7%respectively.The stem diameter of pepper in SC2 group was thicker than CK group in the whole growth period(P<0.05),and it was significantly different at 30 days(P<0.01).Cultivation of pepper root vigor of different treatments at 60 days in continuous cropping were measured,SC2 group of pepper root total absorption area,active absorption area and total surface area compared with the CK group had significant difference(P<0.01),which were 1.9 times,2.3 times and 1.22 timest of CK group.The root activity of SC2 group was stronger than that of CK group,which was beneficial to the nutrient absorption of pepper plants.The interaction between pepper and SC2 was carried out for 20 hours in Sterile environment,then pepper and SC2 were collected.RNA-Seq technique was used to analyze the interaction between SC2 and pepper.The results showed that there were 758 genes in pepper significant differences,of which 573 were up-regulated and 185 genes were down-regulated There were 15 channels in the KEGG pathway,and the difference genes mainly involve metabolism,defense and signal transduction.There were significant differences in the genes related to WRKY transcription factor family and pathogenesis related proteins in pepper,and the increase of defense resistance genes such as heat shock protein and glutathione transferase was beneficial to the growth of pepper.There were 812 genes with significant differences in SC2,of which 465 genes were up-regulated and 347 genes were down-regulated.There were six significant ways to enrich the SC2 pathway,and the difference genes mainly involve secondary metabolism,material transport and secretion.The genes related to the synthesis of fusaricidin and polymyxin in SC2 were significantly up-regulated,and the expression of auxin synthesis-related gene was significantly increased,and 42 genes in ABC transport system were significantly up-regulated.Differences in the expression of pepper and SC2 transcripts can be seen by the interaction of pepper after SC2 treatment of defense metabolism and other related genes have greatly changed.SC2 with the role of pepper metabolism and other related gene expression differences.Which lay the foundation for further study of pepper and SC2 interaction mechanism.