Evidence that the role of plant defensins in radish defense responses is independent of salicylic acid |
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Authors: | Franky R G Terras Iris A M A Penninckx Inge J Goderis Willem F Broekaert |
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Institution: | (1) F.A. Janssens Laboratory of Genetics, Katholieke Universiteit Leuven, Kard. Mercierlaan 92, B-3001 Heverlee-Leuven, Belgium, BE |
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Abstract: | Radish leaves contain two homologous 5-kDa plant defensins which accumulate systemically upon infection by fungal pathogens
(F.R.G. Terras et al., 1995, Plant Cell 7: 573–588). Here we report on the molecular cloning of the cDNAs encoding the two
pathogen-inducible plant defensin isoforms from radish (Raphanus sativus L.) leaves. Tissue-print and whole-leaf electroblot immunostaining showed that the plant defensin peptides not only accumulate
at high levels at or immediately around the infection sites in leaves inoculated with Alternariabrassicicola, but also accumulate in healthy tissue further away from the infection sites and in non-infected leaves from infected plants.
Gel blot analysis of RNA confirmed that expression of plant defensin genes is systemically triggered upon fungal infection
whereas radish PR-1 gene expression is only activated locally. In contrast to the radish PR-1 gene(s), expression of the radish plant defensin genes was not induced by external application of salicylic acid. Activation
of the plant defensin genes, but not that of PR-1 genes, occurred upon treatment with methyl jasmonate, ethylene and paraquat.
Received: 3 December 1997 / Accepted: 3 March 1998 |
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Keywords: | :Alternaria Antifungal peptide Patho-genesis-related protein Raphanus (defensins) |
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