Melhoramento de plantas e resistencia

REVISÃO / REVIEW

CONCEPTS IN PLANT DISEASE RESISTANCE
FRANCISCO XAVIER RIBEIRO DO VALE1, J. E. PARLEVLIET2 & LAÉRCIO ZAMBOLIM1
1

Departamento de Fitopatologia, Universidade Federal de Viçosa, CEP 36571-000, Viçosa, MG, Brasil, e-mail: [e-mail]; 2Department of Plant Breeding (IVP), Wageningen Agricultural University, P.O. Box 386, 6700 AJ
Wageningen, The Netherlands

(Aceito para publicação em 13/08/2001)
Autor para correspondência: Francisco Xavier Ribeiro do Vale
RIBEIRO DO VALE, F.X., PARLEVLIET, J.E. & ZAMBOLIM, L. Concepts in plant disease resistance. Fitopatologia Brasileira 26:577589. 2001.

ABSTRACT
Resistance to nearly all pathogens occurs abundantly in our crops. Much of the resistance exploited by breeders is of the major gene type. Polygenic resistance, although used much less, is even more abundantly available. Many types of resistance are highly elusive, the pathogen apparently adapting very easily them. Other types of resistance, the so-called durable resistance, remain effective much longer. The elusive resistance is invariably of the monogenic type and usually of the hypersensitive type directed against specialised pathogens.

Race-specificity is not the cause of elusive resistance but the consequence of it. Understanding acquired resistance may open interesting approaches to control pathogens. This is even truer for molecular techniques, which already represent an enourmously wide range of possibilities. Resistance obtained through transformation is often of the quantitative type and may be durable in most cases.
Key words: types of resistance; genetics of resistance; acquired resistance.

RESUMO
Conceitos em resistência de plantas a doenças
Na natureza a resistência à maioria das doenças ocorre nas culturas. A maior parte da resistência explorada pelos melhoristas envolve genes maiores ou principais. Resistência poligênica, embora seja muito menos utilizada nos programas de melhoramento,