Modification of competence for in vitro response to Fusarium oxysporum in tomato cells. III. PR-protein gene expression and ethylene evolution in tomato cell lines transgenic for phytohormone-related bacterial genes |
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Authors: | P Bettini E Cosi M G Pellegrini L Turbanti G Vendramin M Buiatti |
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Institution: | (1) Dipartimento di Biologia animale e Genetica “Leo Pardi”, via Romana 17, 50125 Florence, Italy Fax: + 39 55 222565 E-mail: mbuiatti@dbag.unifi.it, IT;(2) Istituto per il Miglioramento Genetico delle Piante Forestali, Consiglio Nazionale delle Ricerche, via Atto Vannucci 13, 50134 Florence, Italy, IT |
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Abstract: | Previous work carried out in our laboratory has shown that, in tomato, the alteration of endogenous phytohormone equilibria
through the integration of Agrobacterium tumefaciens genes for auxin and cytokinin synthesis can modify the active defense response to Fusarium oxysporum f. sp. lycopersici. The susceptible cv ‘Red River’ acquires a stable competence for active defense, particularly when the phytohormone equilibrium
is altered in favour of cytokinins. Here, we analyse the expression of genes involved in the defense response against pathogens,
i.e. pathogenesis-related (PR)-protein genes, in the susceptible ‘Red River’ and resistant ‘Davis’ cultivars transgenic for
the aforementioned genes. Fungal cell-wall components, glutathione, salicylic acid and the ethylene-forming ethephon are used
as “probes” for the induction of defense processes, including ethylene production. The data obtained show that the extracellular
PR-proteins (acidic chitinase and PR-1 protein) that were inducible in the control tissue of the resistant ‘Davis’ cultivar
and not expressed in the susceptible ‘Red River’ cultivar became constitutive in the transgenic tissues of both. On the other
hand, expression of the intracellular PR-proteins (basic chitinase and β-1,3-glucanase) was found to be constitutive in all
cases, both in the control and in the transgenic cell lines of the resistant and the susceptible tomato cultivars. Ethylene
production was higher in ‘Davis’ than in ‘Red River’, and significantly increased in the transgenic cell lines, particularly
when cytokinin synthesis was altered.
Received: 25 February 1998 / Accepted: 7 April 1998 |
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Keywords: | Lycopersicon esculentum Fusarium oxysporum f sp lycopersici Agrobacterium tumefaciens-mediated transformation Phytohormones PR-proteins |
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