New resistance genes in the Zea mays: exserohilum turcicum pathosystem

Abstract

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, F 1 generations and a BC 1 F 1 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).

Association mapping and genetic control for northern leaf blight (Exserohilum turcicum) resistance in maize lines

“…In the present study, we used QTLs on these chromosomes, as well as a QTL on chromosome 3 (Ogliari et al, 2007) and a QTL on chromosome 8 (Chung et al, 2010a;2010b;Wang et al, 2012).…”

“…However, for northern leaf blight, genetic control can be carried out by quantitative resistance with predominant additive gene action and by qualitative resistance, derived from a few non-additive action genes (Ferguson and Carson, 2007). These two types of resistance can be found acting separately or concurrently (Ogliari et al, 2007). The results indicate the existence of approximately 2.5 genes acting in the genetic control of the disease (Table 3).…”

“…The genetic control for resistance to major leaf diseases is described as qualitative in most studies, however, there are some that can be characterized as quantitative. These two types of resistance can be found acting separately or concurrently (Ogliari et al, 2007). Quantitative or horizontal resistance is widely used in the genetic control of northern leaf blight, referring to several genes of small additive effects acting on the expression of the character (Vivek et al, 2010).…”

“…However, for resistance to E. turcicum, genes of non-additive effects coming from genes under dominance and/or epistasis, have been shown to be important (Niehi and Ferreira, 2012). In this context, the quantitative resistance to northern leaf blight can be characterized also by the joint action of additive and non-additive genes (Ogliari, 2007;Vieira et al, 2009). In breeding programs, a tool that stands out for the rapidity and effectiveness in genetic studies of germplasm, has been the use of molecular marker techniques, due to the detection of polymorphism at the molecular level without taking into account environmental influence (Faleiro, 2011).…”

Assessment of Maize (Z<i>ea mays</i> L.) <i>Exserohium Turcicum</i> (Pass.) Leonard and Sugg. Isolates on Different Culture Media in Tanzania

“…Exserohilum turcicum is mostly controlled by resistant varieties derived from qualitative and quantitative genes acting together or separately [32,33,34]. Qualitative resistance is typically race-specific and controlled by single genes (monogenic) whereas quantitative resistance is race non-specific and controlled by many genes [35,36].…”