Identification of differentially expressed genes during pseudomonas fluorescens mediated systemic resistance in cabbage

The study of microbial ecology and the microbial interactions with plants provides an insight into the biocontrol of plant diseases using antagonistic microbes. Pseudomonas fluorescens was used as a biological control agent against black rot disease caused by Xanthomonas campestris pv. campestris. The Suppression subtractive hybridization (SSH) was used to elucidate the differentially expressed genes in cabbage (Brassica oleracea var. capitata) upon the application of Pseudomonas fluorescens. A total of 140 expressed sequence tags (EST) were obtained. The analyses of these ESTs showed that many defense related genes like peroxidase, heat shock proteins, were upregulated. Many transcripts related to signalling pathways and pathogen recognition were identified. The important finding of the study is the identification of the unigene belonging to the SWEET protein family in cabbage. The study also resulted in the identification of 10 unigenes which possibly depict the interaction of Pseudomonas fluorescens in combating disease. These unigenes have been submitted to dbEST. The results show that those genes which are upregulated during pathogen attack are also induced upon application of Pseudomonas fluorescens indicating the possible mechanism of systemic resistance induced by P. fluorescens to combat disease