Transcriptome profile analysis of resistance induced by burdock fructooligosaccharide in tobacco

Burdock fructooligosaccharide (BFO), isolated from the roots of Arcitum lappa, is a novel potential elicitor. Previous studies have shown that BFO induces various defense responses in plants. However, little is known about the mechanism of BFO induced plant responses. The transcriptome profiles in tobacco leaves after treatment with BFO or distilled water were analyzed using Solexa technology. The profiling analysis revealed numerous changes in gene expression after BFO treatment, which resulted in the up-regulation of 169 genes and the down-regulation of 243 genes. The data were confirmed by reverse transcription polymerase chain reaction (RT-PCR) and real-time quantitative RT-PCR. Gene ontology analysis revealed that the differentially expressed genes were mainly involved in stress responses, defense responses, biosynthetic processes, hormone responses, RNA biosynthetic processes, signaling pathways and other processes. The results of this study suggested two important concepts. First, the differential expression of genes involved in plant hormone signaling pathways are related to defense, especially salicylic acid-mediated pathways, such as the genes encoding pathogen related proteins, WRKY transcription factors, Avr9/Cf-9 rapidly elicited protein, SA-activated MAP kinase, jasmonic acid/ethylene-related genes encoding jasmonate ZIM-domain protein and ethylene-responsive transcription factor, gibberellin-related genes encoding flowering promoting factor-like 1 and GA-insensitive dwarf 2, and abscisic acid related gene encoding ABA 8'-hydroxylase CYP707A, indicated that plant hormones and their crosstalk might play a critical role in the defense response to BFO treatment in tobacco. Second, the genes involved in the biosynthesis of secondary metabolites were increased after BFO treatment including epiaristolochene synthase and cinnamoyl-CoA reductase, which serve as attractants in defense against pathogens and herbivores.