International Congress BIOLOGICAL PRODUCTS - Gruppo di ...

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NEW α-ELICITIN ISOFORMS FROM Phytophthora hybernalis AS PROTEIN ELICITORS FOR A
POTENTIAL EMPLOYMENT IN THE BIOLOGICAL PEST MANAGEMENT
R. Capasso*, A. De Martino*, G. Cristinzio**, A. Di Maro*** and A. Parente***
*Dipartimento di Scienze della Pianta, del Suolo e dell’Ambiente, Università degli Studi di Napoli “Federico II”,
Portici, Italy. E-mail: capasso@unina.it
** Dipartimento di Arboricoltura, Botanica e Patologia Vegetale, Università degli Studi di
Napoli “Federico II”, Portici, Italy.
*** Dipartimento di Scienze della Vita, Seconda Università degli Studi di Napoli, Caserta, Italy.
The microbial naturally occurring compounds which are able to induce plant defence mechanisms against
phytopathogenic fungi and bacteria are named elicitors and could be consequently employed in strategies for the
biological control of plant diseases.
The genus Phytophthora produces protein elicitors, named α- and β-elicitins, which show a relative molecular weight
of 10 KDa and 98 amino acids. Their characteristic biological activities are the induction of a hypersensitive response
(HR) and systemic acquired resistance (SAR) in tobacco with the formation of phytoalexins, PR proteins and salycilic
acid; moreover, they induce protection against phytopathogenic microorganisms in tobacco and in some species of
Brassicaceae 1 .
In the present communication we describe the isolation and the preliminary data on the chemical characterization and
elicitor activity on tobacco (Nicotiana tabacum L., cv Rustica) of three new elicitin isoforms H-α1, H-α2 e H-α3,
produced in the culture filtrates of an isolate of Phytophthora hybernalis, the causal agent of rot of citrus fruits, isolated
from diseased plants in the sorrentina peninsula.
The three isoforms have been isolated by four purification steps, of which the final step was represented by a
chromatographic purification on a reverse-phase column (RP-18) eluted at low pressure with a gradient of wateracetonitrile.
It was determined their absolute molecular weight by MALDI Mass Spectrometry, obtaining values of 10239.24 for Hα1,
10235.94 for H-α2 and 10244.28 uma for H-α3.
In studies of elicitor activity carried out testing the hypersensitive response on tobacco, the three isoforms showed
different intensity responses, that is H-α1 proved to be the most active, followed by H-α2, whereas H-α3 proved to be
inactive.
Studies will be carried out on the determination of their primary structure and elicitor effects on other plants of
agricultural interest. The very low dose required for their positive biological effects on tobacco, their protein nature
and the no toxicity of the elicitins for adults 2 , render these new compounds and those previously described 1,3,4 very
interesting for investigations on their possible use in biological pest management programs.
REFERENCES
1. Ponchet, M., Panabieres, F., Milat, M.-L., Mikes, V., Montillet, J.-L., Suty, L., Triantaphylides, C.,
Tirilly, Y., Blein, J.-P., 1999. Are elicitins cryptograms in plant-Oomycete communications? Cell Mol.
Life Sci. 56, 1020-1047.
2. Mikes, V., Blein, J.-P., Milat, M.-L., Ponchet, M., Ricci, P., 1998. Use of elicitins as lipid carriers
and their medical use. Patent PCT Int. Appl. 31 pp Coden; PIXXD2.
3. Capasso, R., Cristinzio, G., Evidente, A.,Visca, C., Ferranti, P., Del Vecchio Blanco, F., Parente, A.,
Elicitin 172 from an isolate of Phytophthora nicotianae, pathogenic to tomato. Phytochem. 50,
703-709.
4. Capasso, R., Cristinzio, G., Di Maro, A. Ferranti, P., Parente, A., 2001. Syringicin a new α-elicitin from
an isolate of Phytophthora syringae, pathogenic to citrus fruit. Phytochem. 58, 257-262.
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