Performing Institution:

NORTH DAKOTA STATE UNIV
FARGO , NORTH DAKOTA 58105

Performing Organization: CROP AND WEED SCIENCES CG 93-37311-9388
Investigator: ANDERSON J A
Investigator: FRANCLLJ

Project Title: MOLECULAR MAPPING OF TAN SPOT RESISTANCE GENES IN WHEAT

Duration: 09/15/93 - 09/30/96

Sub Class:

Wheat, General

Objectives: PROJ. #9304245. The objectives of this research are to estimate the number of genes conditioning resistance to tan spot in a population of recombinant inbred lines of WHEAT; and map these resistance genes on WHEAT chromosomes using DNA markers.

Approach: Resistance to tan spot in the recombinant inbred lines will be assayed by inoculating individual isolates of the tan spot fungus onto seedlings and adult plants, and recording infection type and percent leaf diseased one week after inoculation. Infection type data will be analyzed to determine segregation pattern and estimate the number of gene conditioning resistance. DNA markers (RFLPS and RAPDS) will be utilized to detect genetic polymorphisms in the population. Tan spot reaction and DNA marker type for each member of the population will be compared to identify significant associations and allow mapping to specific chromosomes.

Keywords: PLANT-DISEASES WHEAT TAN-SPOT-(WHEAT) GENETIC-MARKERS PLANT-DISEASE-RESISTANCE GENETIC-MAPPING RFLP RAPD MOLECULAR-GENETICS RECOMBINATION INBREEDING POLYMORPHISM

Progress:

Seedlings of 138 recombinant inbred lines of WHEAT (Triticum aestivum) derived from the cross W-7984/Opata 85 were inoculated with conidia of the tan spot (Pyrenophora tritici-repentis) isolate Pti-2 in two experiments. A third experiment was conducted on a subset of the population to resolve discrepancies in individual line scores from the first two experiments. Phenotypic data exhibited a bimodal distribution, consistent with the segregation of a single major resistance gene with the addition of other minor genes and/or environmental effects. Restriction fragment length polymorphisms (RFLPs) mapped in this population by other investigators were used to identify markers for tan spot resistance genes. Our laboratory has concentrated on mapping group 5 chromosomes in this population. One marker has been identified that explains approximately 35 percent of the phenotypic variation in tan spot reaction among the lines. Seedlings of the entire populations have also been screened for their reaction to infiltration of the Ptr necrosis toxin. The population was completely resistant to this inoculation, indicating that both parents contain a resistance gene at the locus controlling reaction to the necrosis toxin. Adult plant reaction to inoculation with conidia of Pti-2 will be evaluated in greenhouse experiments. Additional isolates will be screened using both conidia and toxin as inoculum. One M.S. student is working on this project.

Publications:

ANDERSON, J.A., AND L.J. FRANCL. 1993. Inheritance of tan spot resistance in a synthetic bread WHEAT. Page 80 in Agronomy Abstracts. American Society of Agronomy, Cincinnati, OH.

Relevance: Disease Control-Field Crops
Relevance: Protection Against Diseases, Parasites
Relevance: Wheat
Relevance: Genetics and Breeding-Plant

General Relevance: WHEAT
General Relevance: Protection

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