The genetic basis of flecking and its relationship to disease resistance in the IBM maize mapping population

Abstract

In this paper, we determine the genetic architecture controlling leaf flecking in maize and investigate its relationship to disease resistance and the defense response. Flecking is defined as a mild, often environmentally dependent lesion phenotype observed on the leaves of several commonly used maize inbred lines. Anecdotal evidence suggests a link between flecking and enhanced broad-spectrum disease resistance. Neither the genetic basis underlying flecking nor its possible relationship to disease resistance has been systematically evaluated. The commonly used maize inbred Mo17 has a mild flecking phenotype. The IBM-advanced intercross mapping population, derived from a cross between Mo17 and another commonly used inbred B73, has been used for mapping a number of traits in maize including several related to disease resistance. In this study, flecking was assessed in the IBM population over 6 environments. Several quantitative trait loci for flecking were identified, with the strongest one located on chromosome 6. Low but moderately significant correlations were observed between stronger flecking and higher disease resistance with respect to two diseases, southern leaf blight and northern leaf blight and between stronger flecking and a stronger defense response.

The plant hypersensitive response: concepts, control and consequences

“…B), appearing in several widely used lines as well as in several other species such as barley (Makepeace et al , ), wheat (Nair and Tomar, ) and oats (Ferdinandsen and Winge, ). Recent work has indicated that in some cases flecking seems to be a mild form of misregulated HR (Olukolu et al , ; Vontimitta et al , ).…”

The Genetics of Leaf Flecking in Maize and Its Relationship to Plant Defense and Disease Resistance

“…Despite its potential utility as a convenient marker for disease resistance, there have been few attempts to understand its genetic basis and its relationship to disease resistance. A recent study using 300 lines from the maize intermated B73 3 Mo17 advanced intercross line mapping population identified low but moderately significant positive correlations between increased flecking and increased disease resistance and defense response (Vontimitta et al, 2015). In this study, using much larger populations, we show that the genetic architecture controlling variation in the flecking phenotype is complex.…”

“…A recent study using 300 lines from the maize intermated B73 3 Mo17 population advanced intercross line mapping population identified low but moderately significant positive correlations between increased flecking and increased disease resistance and defense response (Vontimitta et al, 2015). Loci associated with variation in flecking were mapped, although these loci did not colocalize with QTLs identified previously for disease resistance and defense response traits (BalintKurti et al, 2007(BalintKurti et al, , 2008(BalintKurti et al, , 2010Olukolu et al, 2013).…”

“…We have defined leaf flecking as the mild, genetically determined spotting observed on many maize inbred cultivars (Vontimitta et al, 2015;Fig. 1).…”

“…Photographs were taken in Clayton, North Carolina, 12 weeks after planting. This figure is adapted from Figure 1 of Vontimitta et al (2015).…”