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Poster: Molecular & Cellular Plant-Microbe Interactions: Plant Defense Responses


Transcriptome analysis of resistance against Phytophthora cinnamomi and the role of β-cinnamomin elicitins in pathogenicity
M. ISLAM (1), H. Hussain (1), J. Rookes (2), A. Chambery (3), A. Schallmey (4), W. Oßwald (5), D. Cahill (2) (1) Deakin University, Australia; (2) Deakin University, Australia; (3) Università degli Studi di Napoli, Italy; (4) RWTH Aachen University, Germa

Resistance to the destructive oomycete pathogen Phytophthora cinnamomi is rare. We have explored resistance in roots, following infection, of the Australian native monocot Lomandra longifolia. Inoculated plants developed restricted lesions and analysis of lignin, callose and hydrogen peroxide indicated their involvement in resistance. We then used a transcriptomic approach to further examine resistance in this system. As the genome of L. longifolia is not sequenced, we performed RNA-seq analysis and the data showed the elevated expression of a range of resistance-related genes including those involved in jasmonic acid synthesis, lignin biosynthesis and in disease resistance signalling. Blast2GO analysis of contigs revealed the presence of elicitin and elicitin-like proteins. We then investigated the role of elicitins in pathogenicity of P. cinnamomi. Elicitins were isolated from liquid culture and different isoforms were identified by isoelectric focusing analysis. A β-cinnamomin elicitin was purified, an antibody produced and its specificity was shown by Western blot analysis. β-cinnamomin production at different life stages of the pathogen was confirmed by confocal microscopy. Elicitins were also detected in inoculated roots of the susceptible plant species, Lupinus angustifolius. Elucidation of resistance-related mechanisms and pathogenicity factors provides opportunities for modification of susceptible plants and identification of targets to prevent infection.