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A new catalytic activity from tobacco converting 2‐coumaric acid to salicylic aldehyde
Author(s) -
Malinowski Jacek,
Krzymowska Magdalena,
Godoń Kamil,
Hennig Jacek,
Podstolski Andrzej
Publication year - 2007
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2006.00837.x
Subject(s) - salicylic acid , tobacco mosaic virus , nicotiana tabacum , phenylpropanoid , biochemistry , arabidopsis thaliana , biology , systemic acquired resistance , enzyme , chemistry , biosynthesis , arabidopsis , gene , virus , virology , mutant
Salicylic acid (SA) mediates plant response to pathogen invasion, resulting in hypersensitive response and in the formation of systemic acquired resistance. It is well known that Nicotiana tabacum and other plants respond to Tobacco Mosaic Virus (TMV) infection by increasing the content of SA but the details of SA biosynthesis are still not fully understood. Generally, SA may originate directly from isochorismate ( Arabidopsis thaliana ), or its C 6 –C 1 skeleton could be synthesized via the phenylpropanoid pathway by β‐oxidation of trans ‐cinnamic acid ( N. tabacum ), 2‐coumaric acid (OCA) ( Gaulteria procumbens , Lycopersicum esculentum ) or by retro‐aldol reaction of trans ‐cinnamoyl‐CoA ( Hypericum androsaemum ). We report here a novel putative enzyme activity from tobacco, salicylic aldehyde synthase (SAS), catalysing non‐oxidative formation of salicylic aldehyde (SALD) directly from OCA. This chain‐shortening activity is similar to that of 4‐hydroxybenzaldehyde synthase from Vanilla planifolia , Lithospermum erythrorhizon , Daucus carota , Solanum tuberosum and Polyporus hispidus but the enzyme differs in the kinetics of the reaction, substrate specificity and requirements for reducing cofactors. SAS activity is constitutively expressed in healthy tobacco leaves and doubles as a result of infection with TMV. Moreover, the product of SAS activity—SALD, applied exogenously on tobacco leaves, stimulates peroxidase activity and enhances resistance to consecutive infection with TMV. These observations could suggest a contribution of SAS and SALD to the response of tobacco to TMV infection.