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High‐affinity binding site for ethylene‐inducing xylanase elicitor on Nicotiana tabacum membranes
Author(s) -
Hanania Uri,
Avni Adi
Publication year - 1997
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1997.12010113.x
Subject(s) - elicitor , nicotiana tabacum , membrane , biochemistry , fluorescein isothiocyanate , binding site , biology , biophysics , gene , fluorescence , physics , quantum mechanics
Summary Challenge of Nicotiana tabacum cv Xanthi with the ethylene‐inducing xylanase (EIX) from Trichoderma viride causes rapid induction of plant defense responses leading to hypersensitive necrosis. This phenomenon is cultivar‐specific; no response is detected when N. tabacum cv Hicks is similarly treated. The responsiveness is determined in tobacco and tomato by a single dominant gene. EIX was labeled with fluorescein‐isothiocyanate and incubated with cell suspension cultures, protoplasts or microsomal membranes. Binding of EIX to the microsomal membranes was found to be specific and saturable, with a dissociation constant of 6.2 nM. Using confocal laser microscopy, the EIX binding site was localized to the plasma membrane. Binding of EIX to its high‐affinity site occurred in responsive species. These results demonstrate the existence of a high‐affinity binding site for EIX on the plasma membrane of responsive cultivars. Chemical cross‐linking of EIX to microsomal membranes from responding plants revealed a 66 kDa protein complex. This protein may function as the receptor that mediates the hypersensitive response induced by EIX binding.