Abstract

OGLIARI, Juliana Bernardi; GUIMARAES, Marco Antônio; GERALDI, Isaías Olívio  and  CAMARGO, Luis Eduardo Aranha. New resistance genes in the Zea mays: exserohilum turcicum pathosystem. Genet. Mol. Biol. [online]. 2005, vol.28, n.3, pp. 435-439. ISSN 1415-4757.  http://dx.doi.org/10.1590/S1415-47572005000300017.

The use of monogenic race-specific resistance is widespread for the control of maize (Zea mays L.) helminthosporiosis caused by Exserohilum turcicum. Inoculation of 18 Brazilian isolates of E. turcicum onto elite maize lines containing previously identified resistance genes and onto differential near-isogenic lines allowed the identification of new qualitative resistance genes. The inoculation of one selected isolate on differential near-isogenic lines, F₁ generations and a BC₁F₁ population from the referred elite lines enabled the characterization of the resistance spectrum of three new genes, one dominant (HtP), one recessive (rt) and a third with non-identified genetic action. Three physiological races of the pathogen were also identified including two with new virulence factors capable of overcoming the resistance of one of the resistance genes identified here (rt).

Keywords : Northern leaf blight; genetic inheritance; resistance genes; races; maize.