Poster: Plant-pathogen interactions
Abs #
525: Altered gene expression during the host-pathogen interaction of witches, broom disease
Interaction of the fungus Crinipellis perniciosa with Theobroma cacao causes witches’ broom disease. The pathogen causes excessive vegetative growth in its uninucleate phase and necrosis in binucleate phase. The death of the host enables the saprophytic phase of the fungus to produce fruiting bodies and eventually basidiospores. The phase transition in Crinipellis depends on the developmental stage of the host tissue and occurs in 3-5 d on mature and 10-12 d on immature leaves of cacao. To understand the molecular changes during the development of the disease, immature cocoa leaves were infected with the primary mycelium of C. perniciosa. Using mRNA differential display 53 differentially expressed genes were isolated 3 d after infection of leaves. Of these genes, 22 were down-regulated (leaf 7, fungus 15) and 31 (leaf 17, fungus 1, leaf/fungus 13) were upregulated. Eleven of the upregulated genes were expressed de novo upon host-pathogen interaction. Thirty differentially expressed genes were cloned, sequenced and their putative function was identified by comparison with data bases. The identified genes code for pathogenesis/stress-related proteins (PR- 2, 9, and 14) in the host, and development and metabolism related proteins in the pathogen. The upregulation of hormone, stress, and signal transduction-related proteins in the host and down-regulation of the same along with the genes that influence metabolism in the pathogen, signify defense-related recognition and response processes during the host-pathogen interaction. The temporal changes of these genes 5, 10, 15 and 20 d post infection will improve our understanding of disease-related gene expression. Controlling expression of some of these genes may ameliorate pathogen-induced damage to the host.
