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

Abstract

The aim of this work was to identify genomic regions associated with northern leaf blight resistance (Exserohilum turcicum) in common maize lines and to study the control involved in the resistance. For association mapping, 72 maize lines were previously genotyped for SNP markers on the 650K platform (Affymetrix®), and their respective genotypic values were predicted by mixed models for northern leaf blight. In order to avoid spurious associations between SNP markers and the studied character, the analysis of population structure was initially performed. The analysis of association between the SNP and northern leaf blight markers was carried out using a linear mixed model. For the study of genetic control, the experiment was conducted in 2016 and it was composed of randomized blocks with three repetitions. Through the notes attributed to the lines and their respective generations, the genotypic data related to the inheritance of the studied disease were extracted. Analyzing the results, QTLs were found on chromosomes 1, 2, 3, 4, 6, 8, 9 and 10 for northern leaf blight in maize, which may increase, reduce or even override the effect of this attribute. Among the QTLs found, five genomic regions were detected for increased resistance to northern leaf blight with the use of SNP markers, found in chromosomes 3 (SNP210703), 8 (SNP507268 and SNP507269), 9 (SNP544616) and 10 (SNP610500). The genetic control of resistance to northern leaf blight is quantitative, with the additive effects being more important in the character determination. In addition, it presents high restricted heritability (88%), which allows good selection efficiency and selection gains.

Mapping and Validation of Major Quantitative Trait Loci for Resistance to Northern Corn Leaf Blight Along With the Determination of the Relationship Between Resistances to Multiple Foliar Pathogens of Maize (Zea mays L.)

“…The QTL localized in chromosome bin 5.04 was previously detected in the NAM population (Poland et al, 2011) and is known to contain a candidate gene, GRMZM2G024612 (Xia et al, 2020). The genomic region in chromosome 8 is important as two resistant genes Ht2 and Htn1 were identified previously (Zaitlin et al, 1992;Simcox and Bennetzen, 1993;Hurni et al, 2015;Kaefer et al, 2017). Wisser et al (2006) reported Histatin-1 (Htn1) as a maize disease resistance gene against NCLB and is known to encode a wall-associated receptor-like kinase that acts as an important component of the plant innate immune system by perceiving pathogen or host-derived elicitors (Hurni et al, 2015).…”

Diallel analysis for resistance to northern leaf blight in popcorn under contrasting nitrogen availability

“…Results of the joint analysis indicated that developing NLBresistant hybrids for growing under different nitrogen availability conditions and locations, choosing a line with larger GCA can contribute to an effective reduction of AUDPC/S. Kaefer et al (2017), studying the genetic control of NLB in corn lines, showed that additive effects are mainly responsible for disease resistance. Such statement corroborates our results since GCA result from additive gene action in trait expression.…”

Genomics-Assisted Breeding for Quantitative Disease Resistances in Small-Grain Cereals and Maize

“…High levels of quantitative NCLB resistance have been detected in non-adapted (sub)tropical materials [ 96 , 97 , 98 ] that might be used for widening the resistance diversity in European maize. In a multi-parental QTL mapping, 17 QTLs distributed along the ten chromosomes were identified, each QTL explaining 3.6 to 32.0% of the genotypic variance [ 98 ].…”