Mapping and Genetic Dissection of Loci Conditioning Disease … · 2015-10-22 · most important...
1
Background Quantitative resistance has been widely used to confer durable resistance for disease control. To gain insights into the nature and underlying genetics of quantitative resistance, our group has been using a range of complementary QTL approaches to identify, characterize and dissect loci conditioning disease resistance (disease QTLs) in maize. Two methods – chromosomal segment substitution lines (CSSLs; Szalma et al., 2007) and heterogeneous inbred family strategy (HIF; Tuinstra et al., 1997), were applied to simultaneously map QTLs and generate near-isogenic lines (NILs). The primary emphasis of this study is to identify and characterize QTLs for resistance to northern leaf blight (NLB), one of the most important corn diseases in tropical and temperate environments. Second, the concept of multiple disease resistance (MDR) is being explored in order to help farmers reduce their loss to a range of diseases. A large number of disease QTLs have been mapped in the maize genome, and clusters of QTLs for various diseases were identified in some chromosomal regions (Wisser et al., 2006). This and other evidence suggests the existence of loci that condition MDR. We used HIFs derived from MDR maize lines to analyze disease QTLs, focusing on regions of the genome associated with MDR. Outcomes I. QTLs identified using chromosomal segment substitution lines (CSSLs) – Several NLB-QTLs were mapped in CSSLs derived from B73 x Tx303 (Fig. 1 and Table 1). Their phenotypic expression was similar at different plant developmental stages (Fig. 2). – Two NLB-QTLs with larger effects, B73 allele at bin 1.02 (qEt1.02 B73 ) and Tx303 allele at bin 1.06 (qEt1.06 Tx303 ), have been further validated (Fig. 3). Their effectiveness on pathogenesis is under investigation. II. QTLs identified using heterogeneous inbred families (HIFs) – A series of NIL pairs contrasting for chromosomal regions associated with MDR is developed (Table 2). By systemically characterizing the NIL pairs for resistance to multiple diseases, several disease QTLs were identified, most of them are effective for single diseases. – The CML52 allele at bin 6.05 (qEt6.05 CML52 ) confers broad-spectrum resistance to three vascular diseases – NLB, ASR and Stewart’s wilt (Fig. 4). – The DK888 allele at bin 8.06 ( qEt8.06 DK888 ) was found to condition quantitative race-specific resistance to NLB (Fig. 5). This locus, likely Htn1, has been fine-mapped to a region of ~ 5 - 7 Mb (Fig. 6). I. I. QTLs identified using chromosomal segment substitution lines ( chromosomal segment substitution lines ( CSSLs CSSLs ) ) The TBBC3 population (Szalma et al., 2007) consists of 82 lines with an average 89% B73 constitution. Each line carries a different set of introgressions from Tx303. We screened this population for lines that differed significantly in disease resistance from the B73 recurrent parent line and from the rest of the population. II. II. QTLs identified using heterogeneous inbred families ( heterogeneous inbred families ( HIFs HIFs ) ) In HIF analysis, intermediate materials from breeding programs are used to develop nearly-isogenic line (NIL) pairs that are isogenic at the majority of loci, but differ at a specific QTL. 74 SSR markers covering 38 bins associated with MDR-QTL were targeted for NIL construction, based on a consensus map of disease QTL in maize (Wisser et al., 2006). HIF-derived NILs were developed from B73 x CML52 and S11 x DK888. The tropical lines CML52 and DK888 were chosen based on their superior resistance to NLB, gray leaf spot (GLS), southern leaf blight (SLB), and other diseases. We hypothesized that: 1) maize genotypes showing MDR phenotypes harbor alleles contributing broad-spectrum resistance, and 2) chromosomal regions where disease QTLs co-localized are enriched with defense-related genes. Chromosomal regions associated with multiple disease resistance Maize disease QTL consensus map (Wisser et al., 2006) Markers tested in CML52 HIFs Markers tested in both CML52 and DK888 HIFs Erwinia wilt Viral diseases Aspergillus flavus Ear rot and stalk rot Common smut Downy mildew Common rust Southern rust Gray leaf spot Southern leaf blight Northern leaf blight Disease QTL Flowering time QTL Chromosome 6 QTL for race-specific resistance to NLB Bin 8.06 in the maize genome is known associated with resistance to NLB and several other important diseases. Two qualitative resistance loci and several QTLs for NLB resistance were localized to this chromosomal region, and the effect has also been identified by us in the nested association mapping (NAM) population (poster 220 by Poland et al.) and recurrent selection mapping population (Wisser et al., submitted). To elucidate this complex locus, we captured the resistance allele from DK888 (qEt8.06 DK888 ), and are dissecting this region for map-based cloning. Conclusions 1. The use of CSSLs and HIFs was found to be effective for QTL analysis and NIL development. 2. The disease QTL consensus map served as a reference for targeted QTL mapping. By targeting 25 out of 41 bins that were previously reported to be associated with NLB resistance, we have successfully identified seven NLB-QTLs in bins 1.06, 1.07-1.08, 5.03, 6.05, 8.02-8.03, and 8.06. With the derived NILs, we are working towards map-based cloning for two QTLs of interest – qEt6.05 CML52 and qEt8.06 DK888 . 3. The value of the disease QTL consensus map to MDR-QTL prediction is still unclear. The limitation comes from low precision and accuracy of QTL mapping, and disease QTLs initially identified in diverse mapping populations. Our work on HIFs from only two resistance donors is not sufficient to clarify the question. References Tuinstra et al. (1997) Theor. Appl. Genet. 95: 1005-1011. Szalma et al. (2007) Theor. Appl. Genet. 114: 1211-1228. Wisser et al. (2006) Phytopathology 96: 120-129. Wisser et al. submitted. Acknowledgements Stephen Kresovich Institute for Genomic Diversity, Cornell University Margaret Smith Dept. of Plant Breeding and Genetics, Cornell University Funding from Ministry of Education, Taiwan; the Generation Challenge Program; and The McKnight Foundation. CML52 NILs contrasting for bin 6.05 Fig. 4. QTL for multiple disease resistance qEt6.05 CML52 conditions resistance to NLB, ASR, and Stewart’s wilt. Development of the three diseases all involves biotrophic interaction with newly infected cells, and subsequent colonization and destruction of the vascular tissue. We hypothesize that resistance is expressed in the xylem, and thus not against pathogens attacking other tissues. Genetic dissection of this MDR-QTL (~24 Mb) is undergoing, in order to determine whether the associated resistance is due to pleiotropy or linkage, and to shed light on the underlying defense mechanisms. qEt6.05 CML52 is the only MDR-QTL found in this study. The lack of MDR-QTL can be due to: – CML52 and DK888 have distinct QTLs for resistance to different diseases. – Background effect: Each derived NIL pair is in a unique genetic background. A susceptible background is needed for accurate detection of disease QTLs, especially minor QTLs. However, it is rather difficult to create a genetic background susceptible to many diseases, considering the diverse requirements of different pathogens and their different interaction patterns with host plant. DK888 S11 DK888 S11 EtNY001 race 0 race 1 race 23N DK888 S11 DK888 S11 10 20 15 5 0 Incubation period Fig. 5. Race specificity and map position of qEt8.06 DK888 suggest that it encompasses Htn1, a major gene that delays lesion development. NLB resistance of 82 TBBC3 CSSLs Fig. 1. The full set of 82 CSSLs was screened in NY and NC in 2006, and the outliers with introgressions of interest were identified. Overall susceptibility of the CSSL population suggested a few major QTLs in Tx303, and many minor QTLs in B73. NLB resistance of 15 selected TBBC3 lines * 0.01<P<0.05, ** 0.001<P< 0.01, and *** P<0.001 Table 1. Several NLB-QTLs were mapped by confirming the resistance effect in a subset of 15 selected CSSLs in NY and NC in 2007. Consistent - 2 envirs, 2 years -15 -10 -5 0 5 10 15 -400 -200 0 200 400 Adjusted AUDPC (area unit) (inoculated on young plants) Ajusted AvgDLA (%) (inoculated on adult plants) Fig. 2. QTL expression vs. plant maturity Inoculation and disease evaluation were conducted respectively on juvenile and adult plants. The positive correlation of disease levels revealed that the effects of the NLB-QTLs were not affected by different plant developmental stages. B73 qEt1.06 Tx303 Loss of qEt1.02 B73 Fig. 3. qEt1.02 B73 and qEt1.06 Tx303 are two NLB-QTLs with larger effects. They have been validated in F 2 populations and derived F 3 lines. Their effectiveness on pathogenesis is under investigation in derived NILs. Preliminary work suggested that qEt1.06 Tx303 protects plants from fungal penetration, while qEt1.02 B73 reduces the efficiency of hyphae growing into the vascular system (for details, see poster 192 by Walsh et al.). NLB ASR Stewart’s wilt DK888 No — No No CML52? a No CML52 No CML52 or B73 (epistasis btw QTL in bin 2.10 and 5.03) No CML52? a CML52? a NLB — — — — — No No No No No No No No GLS b S11 / DK888 B73 / CML52 Cross of origin — No No No No No 8.06 — No No S11 b No No 6.05 — No No S11 b No No 5.06 — S11 b No No No DK888 b 5.04 — No No No No No 3.04 — No No No No No 8.02/03 NLB, rust — No No CML52 b No No 7.04 SLB, ALB CML52 b No No CML52 b No No 6.05 NLB, ALB, rust — CML52 b No No No No 3.06 — No No No No No 2.10, 5.03 SLB — No No No No No 2.04/06 — No No No No No 1.07/08 SLB, ALB — No No No No No 1.06 Stewart’s wilt b Smut b Rust b ASR b ALB b SLB b Differential in resistance, but causative QTL unknown Disease resistance (allele conferring resistance) Contrasting regions in available NIL pairs (bin) a The NLB-QTL was identified from corresponding heterogeneous inbred families in 2005 to 2006, but significant phenotypic contrast was not detected in selected NIL pairs at Aurora, 2007. b Data based on one-year field or GH trials, and need to be further validated. (Common rust and common smut are from natural infection.) Table 2. The NIL pairs contrasting for different chromosomal regions were characterized for NLB, GLS, SLB, anthracnose leaf blight (ALB), anthracnose stalk rot (ASR), common rust, common smut and Stewart’s wilt. Fig. 6. Trait-marker association in a population of ~200 F 9 recombinants has localized qEt8.06 DK888 to a region of 5~7 Mb. 11 12 13 14 15 16 17 DK888 Het S11 Allele(s) at qET8.06 Incubation period (days after inoculation) -20 -15 -10 -5 0 5 10 15 20 25 30 TBBC3_39 TBBC3_02 TBBC3_03 Tx303 TBBC3_38 TBBC3_26 TBBC3_77 TBBC3_50 TBBC3_49 TBBC3_88 TBBC3_67 TBBC3_52 TBBC3_05 TBBC3_60 TBBC3_70 TBBC3_76 TBBC3_48 TBBC3_18 TBBC3_80 TBBC3_89 TBBC3_01 TBBC3_20 TBBC3_19 TBBC3_62 TBBC3_63 TBBC3_64 TBBC3_78 TBBC3_14 TBBC3_58 TBBC3_66 TBBC3_83 TBBC3_44 TBBC3_86 TBBC3_32 TBBC3_22 TBBC3_15 TBBC3_75 TBBC3_73 TBBC3_08 TBBC3_11 TBBC3_74 TBBC3_31 TBBC3_35 TBBC3_69 TBBC3_87 TBBC3_51 TBBC3_55 TBBC3_29 TBBC3_90 TBBC3_37 TBBC3_82 TBBC3_72 TBBC3_33 TBBC3_65 TBBC3_57 TBBC3_04 TBBC3_09 TBBC3_24 TBBC3_17 TBBC3_43 TBBC3_68 TBBC3_07 TBBC3_71 TBBC3_46 TBBC3_84 TBBC3_85 TBBC3_40 TBBC3_13 TBBC3_34 TBBC3_30 TBBC3_25 TBBC3_27 TBBC3_10 TBBC3_21 TBBC3_06 TBBC3_59 TBBC3_23 TBBC3_41 TBBC3_28 TBBC3_61 TBBC3_53 TBBC3_42 TBBC3_36 Maize Genotype Adjusted AUDPC (area unit) (NY) -2.0 -1.0 0.0 1.0 2.0 3.0 Adjusted disease severity (scale) (NC) Adjusted AUDPC (NY) Adjusted Dis (NC) B73 Tx303 umc1828 umc1997 umc2395 umc2356 umc1149 bnlg240 umc2361 umc2199 umc1777 umc1316 bnlg1724 umc1728 QTL region identified in F 7 umc1287 umc2210 DK888 allele at umc2210 and umc1287 confers partially dominant resistance qEt6.05 B73 qEt6.05 qEt6.05 CML52 CML52 qEt6.05 B73 qEt6.05 B73 qEt6.05 CML52 qEt6.05 CML52 Mapping and Genetic Dissection of Loci Conditioning Disease Resistance in Maize Chia-Lin Chung 1 , Joy Longfellow 1 , Ellie Walsh 1 , George Van Esbroek 3 , Peter Balint-Kurti 3 and Rebecca Nelson 12 1 Dept. of Plant Pathology and Plant-Microbe Biology, and 2 Dept. of Plant Breeding and Genetics, Cornell University, Ithaca, NY 14853, USA 3 USDA-ARS; Dept. of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
Transcript of Mapping and Genetic Dissection of Loci Conditioning Disease … · 2015-10-22 · most important...
BackgroundQuantitative resistance has been widely used to confer durable resistance for disease control. To gain insights into the nature and underlying genetics of quantitative resistance, our group has been using a range of complementary QTL approaches to identify, characterize and dissect loci conditioning disease resistance (disease QTLs) in maize. Two methods – chromosomal segment substitution lines (CSSLs; Szalma et al., 2007) and heterogeneous inbred family strategy (HIF; Tuinstra et al., 1997), were applied to simultaneously map QTLs and generate near-isogenic lines (NILs).
The primary emphasis of this study is to identify and characterize QTLs for resistance to northern leaf blight (NLB), one of the most important corn diseases in tropical and temperate environments. Second, the concept of multiple disease resistance (MDR) is being explored in order to help farmers reduce their loss to a range of diseases. A large number of disease QTLs have been mapped in the maize genome, and clusters of QTLs for various diseases were identified in some chromosomal regions (Wisser et al., 2006). This and other evidence suggests the existence of loci that condition MDR. We used HIFs derived from MDR maize lines to analyze disease QTLs, focusing on regions of the genome associated with MDR.
OutcomesI. QTLs identified using chromosomal segment substitution lines (CSSLs)
– Several NLB-QTLs were mapped in CSSLs derived from B73 x Tx303 (Fig. 1 and Table 1). Their phenotypic expression was similar at different plant developmental stages (Fig. 2).
– Two NLB-QTLs with larger effects, B73 allele at bin 1.02 (qEt1.02B73) and Tx303 allele at bin 1.06 (qEt1.06Tx303), have been further validated (Fig. 3). Their effectiveness on pathogenesis is under investigation.
II. QTLs identified using heterogeneous inbred families (HIFs)– A series of NIL pairs contrasting for chromosomal regions associated with MDR is developed (Table 2). By systemically characterizing
the NIL pairs for resistance to multiple diseases, several disease QTLs were identified, most of them are effective for single diseases. – The CML52 allele at bin 6.05 (qEt6.05CML52) confers broad-spectrum resistance to three vascular diseases – NLB, ASR and Stewart’s
wilt (Fig. 4). – The DK888 allele at bin 8.06 (qEt8.06DK888) was found to condition quantitative race-specific resistance to NLB (Fig. 5). This locus,
likely Htn1, has been fine-mapped to a region of ~ 5 - 7 Mb (Fig. 6).
I.I. QTLs identified using chromosomal segment substitution lines (chromosomal segment substitution lines (CSSLsCSSLs))
The TBBC3 population (Szalma et al., 2007) consists of 82 lines with an average 89% B73 constitution. Each line carries a different set of introgressions from Tx303. We screened this population for lines that differed significantly in disease resistance from the B73 recurrent parent line and from the rest of the population.
II.II. QTLs identified using heterogeneous inbred families (heterogeneous inbred families (HIFsHIFs))
In HIF analysis, intermediate materials from breeding programs are used to develop nearly-isogenic line (NIL) pairs that are isogenic at the majority of loci, but differ at a specific QTL. 74 SSR markers covering 38 bins associated with MDR-QTL were targeted for NIL construction, based on a consensus map of disease QTL in maize (Wisser et al., 2006). HIF-derived NILs were developed from B73 x CML52 and S11 x DK888. The tropical lines CML52 and DK888 were chosen based on their superior resistance to NLB, gray leaf spot (GLS), southern leaf blight (SLB), and other diseases. We hypothesized that: 1) maize genotypes showing MDR phenotypes harbor alleles contributing broad-spectrum resistance, and 2) chromosomal regions where disease QTLs co-localized are enriched with defense-related genes.
Chromosomal regionsassociated with
multiple disease resistanceMaize disease QTL consensus map
(Wisser et al., 2006)
Markers tested in CML52 HIFsMarkers tested in both CML52 and DK888 HIFs
Erwinia wilt
Viral diseases
Aspergillus flavus
Ear rot and stalk rot
Common smut
Downy mildew
Common rust
Southern rust
Gray leaf spot
Southern leaf blight
Northern leaf blight
Disease QTLFlowering time QTL
Chromosome 6
QTL for race-specific resistance to NLBBin 8.06 in the maize genome is known associated with resistance to NLB and several other important diseases. Two qualitative resistance loci and several QTLs for NLB resistance were localized to this chromosomal region, and the effect has also been identified by us in the nested association mapping (NAM) population (poster 220 by Poland et al.) and recurrent selection mapping population (Wisser et al., submitted). To elucidate this complex locus, we captured the resistance allele from DK888 (qEt8.06DK888), and are dissecting this region for map-based cloning.
Conclusions1. The use of CSSLs and HIFs was found to be effective for QTL analysis and NIL development.
2. The disease QTL consensus map served as a reference for targeted QTL mapping. By targeting 25 out of 41 bins that were previously reported to be associated with NLB resistance, we have successfully identified seven NLB-QTLs in bins 1.06, 1.07-1.08, 5.03, 6.05, 8.02-8.03, and 8.06. With the derived NILs, we are working towards map-based cloning for two QTLs of interest –qEt6.05CML52 and qEt8.06DK888.
3. The value of the disease QTL consensus map to MDR-QTL prediction is still unclear. The limitation comes from low precision and accuracy of QTL mapping, and disease QTLs initially identified in diverse mapping populations. Our work on HIFs from only two resistance donors is not sufficient to clarify the question.
ReferencesTuinstra et al. (1997) Theor. Appl. Genet. 95: 1005-1011.Szalma et al. (2007) Theor. Appl. Genet. 114: 1211-1228. Wisser et al. (2006) Phytopathology 96: 120-129.Wisser et al. submitted.
AcknowledgementsStephen Kresovich Institute for Genomic Diversity, Cornell UniversityMargaret Smith Dept. of Plant Breeding and Genetics, Cornell UniversityFunding from Ministry of Education, Taiwan; the Generation Challenge Program; and The McKnight Foundation.
CML52 NILs contrasting for bin 6.05
Fig. 4. QTL for multiple disease resistance
qEt6.05CML52 conditions resistance to NLB, ASR, and Stewart’s wilt. Development of the three diseases all involves biotrophicinteraction with newly infected cells, and subsequent colonization and destruction of the vascular tissue. We hypothesize that resistance is expressed in the xylem, and thus not against pathogens attacking other tissues. Genetic dissection of this MDR-QTL (~24 Mb) is undergoing, in order to determine whether the associated resistance is due to pleiotropy or linkage, and to shed light on the underlying defense mechanisms.
qEt6.05CML52 is the only MDR-QTL found in this study. The lack of MDR-QTL can be due to:
– CML52 and DK888 have distinct QTLs for resistance to different diseases.
– Background effect: Each derived NIL pair is in a unique genetic background. A susceptible background is needed for accurate detection of disease QTLs, especially minor QTLs. However, it is rather difficult to create a genetic background susceptible to many diseases, considering the diverse requirements of different pathogens and their different interaction patterns with host plant.
0
5
10
15
20
DK888 S11 DK888 S11
EtNY001 race 0 race 1 race 23N
DK888 S11 DK888 S11
10
20
15
5
0
Incu
batio
n pe
riod
Fig. 5. Race specificity and map position of qEt8.06DK888 suggest that it encompasses Htn1, a major gene that delays lesion development.
QTL at different plant developmental stages
NLB resistance of 82 TBBC3 CSSLsFig. 1. The full set of 82 CSSLs was screened in NY and NC in 2006, and the outliers with introgressions of interest were identified.
Overall susceptibility of the CSSL population suggested a few major QTLs in Tx303, and many minor QTLs in B73.
NLB resistance of 15 selected TBBC3 lines
* 0.01<P<0.05, ** 0.001<P< 0.01, and *** P<0.001
Table 1.Several NLB-QTLs were mapped by confirming the resistance effect in a subset of 15 selected CSSLs in NY and NC in 2007.
Consistent -2 envirs, 2 years
-15
-10
-5
0
5
10
15
-400 -200 0 200 400
Adjusted AUDPC (area unit)(inoculated on young plants)
Aju
sted
Avg
DLA
(%)
(inoc
ulat
ed o
n ad
ult p
lant
s)
Fig. 2. QTL expression vs. plant maturityInoculation and disease evaluation were conducted respectively on juvenile and adult plants. The positive correlation of disease levels revealed that the effects of theNLB-QTLs were not affected by different plant developmental stages.
B73 qEt1.06Tx303Loss of qEt1.02B73
Fig. 3. qEt1.02B73 and qEt1.06Tx303 are two NLB-QTLs with larger effects. They have been validated in F2 populations and derived F3 lines. Their effectiveness on pathogenesis is under investigation in derived NILs. Preliminary work suggested that qEt1.06Tx303 protects plants from fungal penetration, while qEt1.02B73 reduces the efficiency of hyphae growing into the vascular system (for details, see poster 192 by Walsh et al.).
NLB ASR Stewart’s wiltDK888No—NoNoCML52? aNoCML52No
CML52 or B73 (epistasis btw QTL in bin 2.10 and 5.03)
NoCML52? aCML52? a
NLB
—————NoNoNoNo
NoNoNoNo
GLS b
S11 / DK888
B73 / CML52
Cross of origin
—NoNoNoNoNo8.06—NoNoS11 bNoNo6.05—NoNoS11 bNoNo5.06—S11 bNoNoNoDK888 b5.04—NoNoNoNoNo3.04—NoNoNoNoNo8.02/03
NLB, rust—NoNoCML52 bNoNo7.04SLB, ALBCML52 bNoNoCML52 bNoNo6.05NLB, ALB, rust—CML52 bNoNoNoNo3.06
—NoNoNoNoNo2.10, 5.03SLB—NoNoNoNoNo2.04/06
—NoNoNoNoNo1.07/08SLB, ALB—NoNoNoNoNo1.06
Stewart’swilt b
Smut bRust bASR bALB bSLB b
Differential in resistance, but causative QTL unknown
Disease resistance (allele conferring resistance)Contrasting regions in available NIL pairs (bin)
a The NLB-QTL was identified from corresponding heterogeneous inbred families in 2005 to 2006, but significant phenotypic contrast was not detected in selected NIL pairs at Aurora, 2007.
b Data based on one-year field or GH trials, and need to be further validated. (Common rust and common smut are from natural infection.)
Table 2. The NIL pairs contrasting for different chromosomal regions were characterized for NLB, GLS, SLB, anthracnose leaf blight (ALB), anthracnose stalk rot (ASR), common rust, common smut and Stewart’s wilt.
Fig. 6. Trait-marker association in a population of ~200 F9recombinants has localized qEt8.06DK888 to a region of 5~7 Mb.
11121314151617
DK888 Het S11
Allele(s) at qET8.06
Incu
batio
n pe
riod
(d
ays
afte
r in
ocul
atio
n)
-20-15
-10-505
101520
2530
TBBC
3_39
TBBC
3_02
TBBC
3_03
Tx30
3TB
BC3_
38TB
BC3_
26TB
BC3_
77TB
BC3_
50TB
BC3_
49TB
BC3_
88TB
BC3_
67TB
BC3_
52TB
BC3_
05TB
BC3_
60TB
BC3_
70TB
BC3_
76TB
BC3_
48TB
BC3_
18TB
BC3_
80TB
BC3_
89TB
BC3_
01TB
BC3_
20TB
BC3_
19TB
BC3_
62TB
BC3_
63TB
BC3_
64TB
BC3_
78TB
BC3_
14TB
BC3_
58TB
BC3_
66TB
BC3_
83TB
BC3_
44TB
BC3_
86TB
BC3_
32TB
BC3_
22TB
BC3_
15TB
BC3_
75TB
BC3_
73TB
BC3_
08TB
BC3_
11TB
BC3_
74TB
BC3_
31TB
BC3_
35TB
BC3_
69TB
BC3_
87TB
BC3_
51TB
BC3_
55TB
BC3_
29TB
BC3_
90TB
BC3_
37TB
BC3_
82TB
BC3_
72TB
BC3_
33TB
BC3_
65TB
BC3_
57TB
BC3_
04TB
BC3_
09TB
BC3_
24TB
BC3_
17TB
BC3_
43TB
BC3_
68TB
BC3_
07TB
BC3_
71TB
BC3_
46TB
BC3_
84TB
BC3_
85TB
BC3_
40TB
BC3_
13TB
BC3_
34TB
BC3_
30TB
BC3_
25TB
BC3_
27TB
BC3_
10TB
BC3_
21TB
BC3_
06TB
BC3_
59TB
BC3_
23TB
BC3_
41TB
BC3_
28TB
BC3_
61TB
BC3_
53TB
BC3_
42TB
BC3_
36
Maize Genotype
Adj
uste
d A
UD
PC(a
rea
unit)
(NY
)
-2.0
-1.0
0.0
1.0
2.0
3.0
Adj
uste
d di
seas
e se
verit
y(s
cale
) (N
C)
Adjusted AUDPC (NY)
Adjusted Dis (NC)
B73
Tx303
umc1
828
umc1
997
umc2
395
umc2
356
umc1
149
bnlg
240
umc2
361
umc2
199
umc1
777
umc1
316
bnlg
1724
umc1
728QTL region
identified in F7 um
c128
7
umc2
210
DK888 allele at umc2210 and umc1287 confers partially dominant resistance
qEt6.05B73
qEt6.05qEt6.05CML52CML52
qEt6.05B73
qEt6.05B73
qEt6.05CML52
qEt6.05CML52
Mapping and Genetic Dissection of Loci Conditioning Disease Resistance in MaizeChia-Lin Chung1, Joy Longfellow1, Ellie Walsh1, George Van Esbroek3, Peter Balint-Kurti3 and Rebecca Nelson12
1 Dept. of Plant Pathology and Plant-Microbe Biology, and 2 Dept. of Plant Breeding and Genetics, Cornell University, Ithaca, NY 14853, USA3 USDA-ARS; Dept. of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
