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Genetic Mapping of Powdery Mildew Resistance Genes in Wheat. Ainong Shi Advisors: Steven Leath, and Paul Murphy. North Carolina State University. Wheat. Wheat powdery mildew ( Blumeria graminis f. sp. tritici) is a disease of major importance.
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Genetic Mapping of Powdery Mildew Resistance Genes in Wheat Ainong Shi Advisors: Steven Leath, and Paul Murphy North Carolina State University
Wheat powdery mildew (Blumeria graminis f. sp. tritici) is a disease of major importance. The use of single gene resistance is the primary method of control of this disease. Identification of molecular markers and genetic mapping can provide a tool for marker assisted breeding.
Objective • Identify molecular markers • Genetic mapping of genes for powdery mildew resistance in wheat
Genetic mapping procedure Phenotype Evaluation Primer Screening Linkage Analysis Genetic Map
An example Identification and mapping of Pm25 gene for wheat powdery mildew resistance
(R) (S) Coker 68-15 x NC96BGTA5 F1 x Coker 68-15 F2 BC1F1 X Obtaining segregating populations for genetic analysis
Detached leaf technique An example of detached leaf technique for reactions to powdery mildew in a F2 population. The culture dish contains 35 primary leaf segments from 35 F2 plants of a Coker 68-15/NCBGTA5 F2 population and six leaf segments from susceptible Check Chancellor on the each side.
Assessment of Reaction to Powdery Mildew 0 1 2 3 4 5 6 7 8 9 • A scale of 0 to 9 • Resistant: 0-3 • Intermediate: 4-6 • Susceptible: 7-9
Reactions to isolate 209a2 of Bgt in Coker 68-15/NCBGTA5 F2 and Coker 68-15*2/NCBGTA5 BC1F1 populations Res. Sus. Exp. c2 Gene -------------------------------------------------------------------------- F2 189 77 3:1 2.210 Pm25 BC1F1 55 52 1:1 0.08 F2 Infection type Frequency
Primer Screening • Method: Bulked segregant analysis (BSA) • Segregating population: Coker 68-15*2/NCBGTA5 BC1F1 • R bulked from 30 high resistant plants • S bulked from 30 high susceptible plants • A total of 156 ten-base random primers
An example for BSA Amplification pattern from RAPD marker OPX061050 for Pm25 in four wheat materials: 1. Coker 68-15 (None), 2. NC96BGTA5 (Pm25), 3. S bulked (None), 4. R bulked (Pm25),
Amplification pattern of DNA detecting OPX061050, OPAG04950, and OPAI14600 RAPD fragments in the Coker 68-15*2/NC96BGTA5 BC1F1 population. Lane 1 to 5 from susceptible plants and lane 6 to 11 from resistant plants with lane 1 and 7 indicating recombinants.
_______________________________________________ Rec Dist Marker Frac cM id Name _______________________________________________ (4) OPAI14600 (4.2%) 4.4 (2) OPX061050 (4.2 %) 4.4 (3) OPAG04950 (11.3 %) 12.8 (1) Pm25 A genetic map of the region carrying Pm25 constructed from the Coker 68-15*2/NC96BGTA5 BC1F1 population
Another example • Mapping Pm3b gene for resistance • to wheat powdery mildew • Method: NILs • Linkage analysis: F2 seg.
OPAN07 1 2 3 4 5 6 7 • Amplification patterns of DNA from seven ‘Chancellor’ near-isogenic lines with random primers. • Chancellor (Cc, recurrent parent), • Axminister/8*Cc (Pm1), • Ulka/8*Cc (Pm2), • Asosan/8*Cc (Pm3a), • Chul/8*Cc (Pm3b), • Sonora/8*Cc (Pm3c), • Khapli/8*Cc (Pm4a). 1400-bp A total of 332 random Operon primers were used to screen for RAPD markers in the seven ‘Chancellor’ near-isogenic lines.
Chancellor//Chul/8*Cc F2 Isolate Res. Sus. Exp. c2 E314 61 22 3:1 0.100 ------------------------------------------------------- Frequency Infection type
1400bp 1400bp Amplification pattern of DNA detecting OPAN071400 RAPD fragments from the F2 population of Chancellor//Chul/8*Cc. PS=susceptible parent, PR=resistant parent, S=Susceptible individual in the F2 and R=resistant individual in the F2. Lane M is a 1-kb molecular-weight marker.
Co-segregation of reaction of Pm3b to E314 isolate of Bgt and RAPD marker OPAN071400 in the Chancellor/(Chul/8*Cc) F2 population. ________________________________________________________ Locus Phenotype c2Ac2Bc2ABRecombination A B RM* Rm SM Sm (3:1) (3:1) (9:3:3:1) fraction Pm3b AN071400 61 0 1 21 0.100 0.004 81.776** 1.2 ________________________________________________________ * RM = resistant plant with the marker, Rm = resistant without the marker, SM = susceptible with the marker, and Sm = susceptible without the maker.
Pm3b 1.2 OPAN071400 Linkage distance
Sixteen RAPD markers linked to Pm1, Pm3b, Pm12, Pm21, Pm25, pmTD1 and Pm3 locus. Gene RAPD marker Pm1 OPU17750 Pm3b OPAN071400 Pm12 OPAE121350, OPAE12495 OPAH05580, OPAI13490 Pm21 OPAN031700, OPAI01700, OPAL03750 Pm25 OPAI14600, OPX061050, OPAG04950 pmTD1 OPQ09750 Pm3 locus OPS031400, OPN09600, OPN091200
_______________________________________________ Rec Dist Marker Frac cM id Name _______________________________________________ (4) OPAI14600 (4.2%) 4.4 (2) OPX061050 (4.2 %) 4.4 (3) OPAG04950 (11.3 %) 12.8 (1) Pm25 A genetic map of the region carrying Pm25 constructed from the NK-68-15*2/NC96BGTA5 BC1F1 population
Pm3b Pm1 1.2 2.2 OPAN071400 OPU17750 OPAI13490 1.6 Pm3 OPN09600, OPN091200 OPS031400 OPAE12495 3.2 0.0 1.0 3.3 OPAH05580 1.6 Pm12 3.3 OPAE121350
ACKNOWLEDGEMENTS North Carolina State University: Dr. Steven Leath, Dr. J. Paul Murphy, Dr. Martin L. Carson, Dr. Ben-Hui Liu, and Dr. Rebeca C. Rufty.
Thank you! Thank all of you!