high resolution genetic and physical mapping of eastern ...¾a bacterial artificial chromosome (bac)...
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High Resolution Genetic and Physical High Resolution Genetic and Physical Mapping of Eastern Filbert Blight Resistance Mapping of Eastern Filbert Blight Resistance
in Hazelnutin Hazelnut
IV INTERNATIONAL WORKSHOP ON HOST-PARASITE INTERACTIONS IN FORESTRY
Vidyasagar R. Sathuvalli and Shawn A. MehlenbacherVidyasagar R. Sathuvalli and Shawn A. MehlenbacherDepartment of Horticulture, Oregon State UniversityDepartment of Horticulture, Oregon State University
Eastern Filbert Blight in HazelnutEastern Filbert Blight in Hazelnut
Major devastating disease
First identified in southwest Washington –1968
First discovered in Willamette valley – 1986
Moved Southward @ 2‐3 km per year
More than 60 % of Oregon’s hazelnut orchards are affected or in close proximity to diseased orchards.
Causal fungus: Anisogramma anomala
Division: Ascomycota
Sub‐division: Pezizomycotina
Class: Sordariomycetes
Order: Diaporthales
Family: Valsaceae (Dict. Fung., 2001)
extension.oregonstate.edu/.../EC149902‐02.jpg
Jose R. Liberato DPI&F Jose R. Liberato DPI&F Jose R. Liberato DPI&F
Eastern Filbert Blight in HazelnutEastern Filbert Blight in Hazelnut
Adapted & Modified from http://www.eppo.org
Distribution of Distribution of Anisogramma anomalaAnisogramma anomala
Map by Jay W. Pscheidt and Pat Grimaldi, 2006
2004‐05
Life Cycle of Life Cycle of Anisogramma anomalaAnisogramma anomalaWet conditions &
Budbreak
Chilling & dormancy
13‐16 months
Disease Resistance BreedingDisease Resistance BreedingEFB resistance – Important objective of
hazelnut breeding program at OSU
‘Gasaway’ resistance – mostly employed
Resistance controlled by dominant allele at single locus
Most advanced selections – ‘Gasaway’resistance
‘Jefferson’ recently released EFB resistance cultivar
Barcelona JeffersonSusceptible
Resistant
GasawayGasaway JeffersonJefferson
Outline of mapOutline of map‐‐based cloning approachbased cloning approach
Krattinger et al., 2009
Disease resistance Linked Markers
Isolate disease resistance gene
Mapping BAC end markers
A genetic map
A large mapping population and Identification of recombinants
A Bacterial Artificial Chromosome (BAC) library
Probes for BAC library screening for chromosome walking
Requirements for mapRequirements for map‐‐based cloning approachbased cloning approach
Genetic linkage Genetic linkage mapmap
of hazelnutof hazelnut
Mehlenbacher et al. (2006) constructed a genetic linkage map for hazelnut with RAPD and SSR markers
‘Gasaway’ resistance in linkage group 6
Nine RAPD markers within 7.5cM of resistance
A genetic map
A large mapping population and Identification of recombinants
A Bacterial Artificial Chromosome (BAC) library
Probes for BAC library screening for chromosome walking
Requirements for mapRequirements for map‐‐based cloning approachbased cloning approach
Mapping PopulationMapping Population
In 2007, controlled crosses between OSU 252.146 and OSU 414.062 generated 1488 seedlings
07001 – 1080 seedlings07002 – 408 seedlings
07002 is from reciprocal cross, OSU 414.062 x OSU 252.146
Fine scale genetic mappingFine scale genetic mapping
DNA was extracted from 1488 seedlings in 2008
Screened for the presence of RAPD markers 152‐800 and 268‐580
Both markers present – Assumed to be resistant
Both markers absent – Assumed to be susceptible
One marker present and the other absent –inoculated in the greenhouse
Recombinant seedlings were used to map new BAC end markers
152-8000.0
R-locus1.4
268-5804.4
Marker1
Marker2
Inoculated in the greenhouse for disease response
RAPD Marker ScreeningRAPD Marker Screening
_ _ _ _ _ _ _ + + +_ +
UBC152‐800
UBC268‐580
_ +_ _ _ _ _ _ _+ + +
Disease InoculationsDisease Inoculations1 2
3 4
13‐16 months later
Carried out in locked greenhouse
High resolution mapping of EFB resistance High resolution mapping of EFB resistance region with RAPD markersregion with RAPD markers
Screening of 1488 seedlings identified 87 recombinants between RAPD markers 152‐800 and 268‐580.
Linkage map was constructed with 7 RAPDs, 2 HRM and 1 SCAR markers using JoinMap v.4.0
Resistance is flanked by two RAPD markers W07‐375 and X01‐825 at 0.05 and 0.06 cM, respectively.
A genetic map
A large mapping population and Identification of recombinants
A Bacterial Artificial Chromosome (BAC) library
Probes for BAC library screening for chromosome walking
Requirements for mapRequirements for map‐‐based cloning approachbased cloning approach
BAC library of HazelnutBAC library of Hazelnut
Constructed for ‘Jefferson’
Cloning enzyme ‐MboI
Vector ‐ pECBAC1 (BamHI site)
Average insert size – 117kb
Genome coverage – 12x
39,936 clones arrayed in 104 384‐well plates
A genetic map
A large mapping population and Identification of recombinants
A Bacterial Artificial Chromosome (BAC) library
Probes for BAC library screening for chromosome walking
Requirements for mapRequirements for map‐‐based cloning approachbased cloning approach
Probes for Screening BAC libraryProbes for Screening BAC library
9 RAPD markers close to resistance where cloned and sequenced
Two sequence characterized amplified region (SCAR) markers were designed
These new SCAR markers were used to screen the BAC library
152‐800 268‐580
Screening of BAC libraryScreening of BAC libraryPooling and Screening by PCR
Plate pools -
104Row pools -
16 per plateColumn pools -
24 per plateExtract DNA
Screen Plate pools
Screen Row and Column pools
Identify the positive clones
18 SCARs from 9 RAPD markers
Screening twice helps avoid false positives and other PCR artifacts
Sequence the BAC ends
Row pool
Column pool
E
17
Hit:78‐Ex17
Sequence the BAC ends
Design new primers from BAC ends
Map the new markers
Screen the BAC library with new BAC end probes
Identify new BACs
Chromosome WalkingChromosome Walking
Identify the BACs carrying resistance
Markers from BAC end sequencesMarkers from BAC end sequences
Lack of polymorphism in the BAC end markers – a major constraint
Various kinds of markers were developed from BAC end sequences
Sequence Characterized Amplified Region (SCAR)Single Stranded Conformational Polymorphism (SSCP)Simple Sequence Repeat (SSR)High Resolution Melting (HRM)Cleaved Amplified Polymorphic Sequence (CAPS)
Primers were designed either using Primer 3 or LightScanner primer design (HRM) Software
Chromosome WalkingChromosome Walking
Initial Screening with SCARs developed from RAPD markers identified 36 BACs
Two further rounds of chromosome walking were carried out from BAC end markers
A total of 93 BACs were identified
Fine mapping of the EFB resistance regionFine mapping of the EFB resistance region
BE01 BE33
BAC end SCAR markersBAC end SCAR markers
2% Agarose – 90v‐6hrs 2% Agarose – 90v‐2.5hrs
RPSPRSRS SSSS RPSPRSRS SSSS
BE04 -
SSCP
BE05 BE05 ‐‐
SSCPSSCP
RPSP RSRS SS SS
RPSP RSRS SS SS
0.5X MDE®
Gel* ‐
4.0 Watt – 12hrs
0.5X MDE®
Gel* ‐
4.0 Watt – 18hrs
BAC end SSCP Markers BAC end SSCP Markers
* Lonza Rockland, Inc., Rockland, ME, USA
BAC end HRM markersBAC end HRM markers
TBE126 TBE_II_14
Resistant melt curveSusceptible melt curve Susceptible melt curve
HRM‐based RAPD marker X01‐825 HRM‐based RAPD marker W07‐375
Susceptible melt curveResistance melt
curve
Susceptible melt curve
HRMHRM‐‐
Markers from RAPDsMarkers from RAPDs
Fine mapping of the EFB resistance regionFine mapping of the EFB resistance region
High density map – 51 markers + Resistance phenotype
Map spans a distance of 4.45cM
Averages 0.03cM between markers
34 markers placed < 1cM from resistance
High Information Content Fingerprinting (HICF) High Information Content Fingerprinting (HICF) Each BAC screening provided more than one BAC hitHigh Information Content Fingerprinting (HICF) was carried out to merge similar BACsBACs were fingerprinted and assembled using the program FPC v9.3 at a threshold of 1 x e‐35HICF assembled 22 contigs and 23 singletons
FPC output showing the BACs in a single contig
Physical Mapping of EFB resistance regionPhysical Mapping of EFB resistance region
High resolution genetic map and HICF data allowed construction of a physical map.
Sizes of the BACs were estimated using PFGE (Pulse Field Gel Electrophoresis)
Physical Map of the EFB resistance regionPhysical Map of the EFB resistance region
1 RecombinantPlant ID UY44
1 RecombinantPlant ID VC55
Rlocu
s
Identification of resistant contigIdentification of resistant contig
A single recombination event was observed between W07‐375 and resistance
A single recombination event was observed between resistance and HICF13
W07‐375 and HICF13 are from the same contig
Size of the contig is ~ 150kb
Resistant contig consists of 3 overlapping clones
87B766C2243F13
Sequencing of Whole BACsSequencing of Whole BACs
BACs in contigs from 173‐500, AA12‐850, W07‐375 and X01‐825Sequencing with Illumina IIx genome analyzer9 BACs per lane were multiplexed using 3bp barcoded adapters80bp paired end sequencing
Data analysis and BioinformaticsData analysis and Bioinformatics
80bp paired‐end reads were sorted according to the adapter barcodes using perl scrip bcsort_pe.pl (brianknaus.com)
De novo assembly of sequences carried out in three steps
1.
Sequences assembled using Velvet de novo short read assembler
2.
Sequences reassembled using SOPRA de novo assembler
3.
Contigs from Velvet and SOPRA were aligned, trimmed and corrected using CodonCode
Aligner software
CodonCode Aligner CodonCode Aligner
Assembling of BACsAssembling of BACs
Number of contigs : min 1 – max 13 per BACLargest contig : 99kbSmallest contig:350bpApproximate coverage: min 60% ‐max 100%
BACs sequenced with Illumina IIx genome analyzer were searched for the potential genes
Gene prediction carried out using the program AUGUSTUS
Arabidopsis as the gene prediction model
RNA‐Seq data from ‘Jefferson’ as the source for transcript support (Data from Mockler’s lab)
Predicted genes with a cutoff of > 60% of transcript support from RNA‐seq data were analyzed
Amino acid sequences of predicted genes were BLAST(P) searched for protein homology
Ab initio Ab initio Gene AnnotationGene Annotation
1 2
3
4
56
7
Genes predicted by AugustusGenes predicted by Augustus
Total 233 73 43 32
Gene products predicted in a BLASTP searchGene products predicted in a BLASTP search
Potential Candidate Genes in EFB resistance regionPotential Candidate Genes in EFB resistance regionPredicted gene Contig4_g19
Belongs to p‐loop NTPase superfamily
Includes NBS‐LRR type disease resistance proteins
NBS‐LRR forms the major class of R genes so far identified
Predicted gene Contig4_g25Belongs to F‐box superfamily
Plant F‐box genes – one of the largest multi gene superfamilies
Control many important biological functions including disease resistance
SummarySummary
A high resolution genetic map with 1488 seedlings was constructed with 51 markers with an average distance of 0.03cM between markers
A physical map of the EFB resistance region was constructed and the resistance gene was assigned to a single contig of three BACs
Whole BACs in the resistance region were sequenced with Illumina IIx Genome analyzer
Ab initio gene annotation of the sequences identified two potential resistance gene candidates: NBS‐LRR and F‐box genes