Analysis of quantitative disease resistance to southern leaf blight and of multiple disease resistance in maize, using near-isogenic lines

AbstractPlant disease resistance is largely governed by complex genetic architecture. In maize, few disease resistance loci have been characterized. Near-isogenic lines (NILs) are a powerful genetic tool to dissect quantitative trait loci (QTL). We analyzed an introgression library of maize near-isogenic lines (NILs), termed a nested NIL (nNIL) library for resistance to northern leaf blight (NLB) caused by the fungal pathogen Setosphaeria turcica. The nNIL library was comprised of 412 BC5F4 NILs that originated from 18 diverse donor parents and a common recurrent parent, B73. Single nucleotide polymorphisms identified through genotyping by sequencing (GBS) were used to define introgressions and for association analysis. NILs that conferred resistance and susceptibility to NLB were comprised of introgressions that overlapped known NLB QTL. Genome-wide association analysis and stepwise regression further resolved five QTL regions, and implicated several candidate genes, including Liguleless1 (Lg1), a key determinant of leaf architecture in cereals. Two independently-derived mutant alleles of lg1 inoculated with S. turcica showed enhanced susceptibility to NLB. In the maize nested association mapping population, leaf angle was positively correlated with NLB in five recombinant inbred line (RIL) populations, and negatively correlated with NLB in four RIL populations. This study demonstrates the power of a nNIL library combined with high density SNP coverage to resolve QTLs. Furthermore, the role of lg1 in leaf architecture and in resistance to NLB has important applications in crop improvement.Significance Statement (120 words)Understanding the genetic basis of disease resistance is important for crop improvement. We analyzed response to northern leaf blight (NLB) in a maize population consisting of 412 near-isogenic lines (NILs) derived from 18 diverse donor parents backcrossed to a recurrent parent, B73. NILs were genotyped by sequencing to detect introgressed segments. We identified NILs with greater resistance or susceptibility to NLB than B73. Genome-wide association analysis, coupled with stepwise regression, identified 5 candidate loci for NLB resistance, including the liguleless1 gene. The LIGULELESS1 transcription factor is critical in development of the leaf ligular region and influences leaf angle. We found that liguleless1 mutants are significantly more susceptible to NLB, uncovering a pleiotropic role for liguleless1 in development and disease resistance.

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Maize Introgression Library Provides Evidence for the Involvement of liguleless1 in Resistance to Northern Leaf Blight

G3 Genes|Genome|Genetics ◽

10.1534/g3.120.401500 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3611-3622

Author(s):

Judith M. Kolkman ◽

Josh Strable ◽

Kate Harline ◽

Dallas E. Kroon ◽

Tyr Wiesner-Hanks ◽

...

Keyword(s):

Disease Resistance ◽

Quantitative Trait Loci ◽

Quantitative Trait ◽

Leaf Blight ◽

Near Isogenic Lines ◽

Northern Leaf Blight ◽

Leaf Architecture ◽

Isogenic Lines ◽

Trait Loci ◽

Introgression Library

Plant disease resistance is largely governed by complex genetic architecture. In maize, few disease resistance loci have been characterized. Near-isogenic lines are a powerful genetic tool to dissect quantitative trait loci. We analyzed an introgression library of maize (Zea mays) near-isogenic lines, termed a nested near-isogenic line library for resistance to northern leaf blight caused by the fungal pathogen Setosphaeria turcica. The population was comprised of 412 BC5F4 near-isogenic lines that originated from 18 diverse donor parents and a common recurrent parent, B73. Single nucleotide polymorphisms identified through genotyping by sequencing were used to define introgressions and for association analysis. Near-isogenic lines that conferred resistance and susceptibility to northern leaf blight were comprised of introgressions that overlapped known northern leaf blight quantitative trait loci. Genome-wide association analysis and stepwise regression further resolved five quantitative trait loci regions, and implicated several candidate genes, including Liguleless1, a key determinant of leaf architecture in cereals. Two independently-derived mutant alleles of liguleless1 inoculated with S. turcica showed enhanced susceptibility to northern leaf blight. In the maize nested association mapping population, leaf angle was positively correlated with resistance to northern leaf blight in five recombinant inbred line populations, and negatively correlated with northern leaf blight in four recombinant inbred line populations. This study demonstrates the power of an introgression library combined with high density marker coverage to resolve quantitative trait loci. Furthermore, the role of liguleless1 in leaf architecture and in resistance to northern leaf blight has important applications in crop improvement.

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Use of a Maize Advanced Intercross Line for Mapping of QTL for Northern Leaf Blight Resistance and Multiple Disease Resistance

Crop Science ◽

10.2135/cropsci2009.02.0066 ◽

2010 ◽

Vol 50 (2) ◽

pp. 458-466 ◽

Cited By ~ 34

Author(s):

Peter J. Balint-Kurti ◽

Junyun Yang ◽

George Van Esbroeck ◽

Janelle Jung ◽

Margaret E. Smith

Keyword(s):

Disease Resistance ◽

Leaf Blight ◽

Blight Resistance ◽

Northern Leaf Blight ◽

Advanced Intercross Line ◽

Multiple Disease Resistance

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Linked, if Not the Same, Mi-1 Homologues Confer Resistance to Tomato Powdery Mildew and Root-Knot Nematodes

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-06-10-0145 ◽

2011 ◽

Vol 24 (4) ◽

pp. 441-450 ◽

Cited By ~ 22

Author(s):

Alireza Seifi ◽

Isgouhi Kaloshian ◽

Jack Vossen ◽

Daidi Che ◽

Kishor K. Bhattarai ◽

...

Keyword(s):

Disease Resistance ◽

Powdery Mildew ◽

Gene Cluster ◽

Chromosome 6 ◽

R Genes ◽

Near Isogenic Lines ◽

Root Knot Nematodes ◽

Isogenic Lines ◽

Tomato Chromosome ◽

Tomato Powdery Mildew

On the short arm of tomato chromosome 6, a cluster of disease resistance (R) genes have evolved harboring the Mi-1 and Cf genes. The Mi-1 gene confers resistance to root-knot nematodes, aphids, and whiteflies. Previously, we mapped two genes, Ol-4 and Ol-6, for resistance to tomato powdery mildew in this cluster. The aim of this study was to investigate whether Ol-4 and Ol-6 are homologues of the R genes located in this cluster. We show that near-isogenic lines (NIL) harboring Ol-4 (NIL-Ol-4) and Ol-6 (NIL-Ol-6) are also resistant to nematodes and aphids. Genetically, the resistance to nematodes cosegregates with Ol-4 and Ol-6, which are further fine-mapped to the Mi-1 cluster. We provide evidence that the composition of Mi-1 homologues in NIL-Ol-4 and NIL-Ol-6 is different from other nematode-resistant tomato lines, Motelle and VFNT, harboring the Mi-1 gene. Furthermore, we demonstrate that the resistance to both nematodes and tomato powdery mildew in these two NIL is governed by linked (if not the same) Mi-1 homologues in the Mi-1 gene cluster. Finally, we discuss how Solanum crops exploit Mi-1 homologues to defend themselves against distinct pathogens.

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Mapping Resistance Quantitative Trait Loci for Three Foliar Diseases in a Maize Recombinant Inbred Line Population—Evidence for Multiple Disease Resistance?

Phytopathology ◽

10.1094/phyto-100-1-0072 ◽

2010 ◽

Vol 100 (1) ◽

pp. 72-79 ◽

Cited By ~ 57

Author(s):

John C. Zwonitzer ◽

Nathan D. Coles ◽

Matthew D. Krakowsky ◽

Consuelo Arellano ◽

James B. Holland ◽

...

Keyword(s):

Disease Resistance ◽

Quantitative Trait Loci ◽

Inbred Line ◽

Recombinant Inbred Line ◽

Quantitative Trait ◽

Recombinant Inbred ◽

Leaf Blight ◽

Foliar Diseases ◽

Multiple Disease Resistance ◽

Trait Loci

Southern leaf blight (SLB), gray leaf spot (GLS), and northern leaf blight (NLB) are all important foliar diseases impacting maize production. The objectives of this study were to identify quantitative trait loci (QTL) for resistance to these diseases in a maize recombinant inbred line (RIL) population derived from a cross between maize lines Ki14 and B73, and to evaluate the evidence for the presence genes or loci conferring multiple disease resistance (MDR). Each disease was scored in multiple separate trials. Highly significant correlations between the resistances and the three diseases were found. The highest correlation was identified between SLB and GLS resistance (r = 0.62). Correlations between resistance to each of the diseases and time to flowering were also highly significant. Nine, eight, and six QTL were identified for SLB, GLS, and NLB resistance, respectively. QTL for all three diseases colocalized in bin 1.06, while QTL colocalizing for two of the three diseases were identified in bins 1.08 to 1.09, 2.02/2.03, 3.04/3.05, 8.05, and 10.05. QTL for time to flowering were also identified at four of these six loci (bins 1.06, 3.04/3.05, 8.05, and 10.05). No disease resistance QTL was identified at the largest-effect QTL for flowering time in bin 10.03.

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