1. Population Genetics of Puccinia coronata f. sp. avenae Hattie Dambroski and Martin Carson USDA-ARS Cereal Disease Laboratory Saint Paul, MN

2. Oat Crown Rust

3. Puccinia Pathway

4. Objective To study the diversity and population structure of Puccinia coronata. sexual populations in the north asexual populations in the south

5. DNA isolated from germinated and non-germinated urediniospores Five DNA samples isolated from aeciospores 41 dinucleotide microsatellites Target sequence (CA) n Highly Polymorphic, allelic diversity ranges from 2 to 22 Microsatellites

6. Populations Northern Populations MN, ND, SD, WI, NE Southern Populations NC, FL, LA, AL Texas California Foreign Populations Brazil, Israel, Russia, Egypt, Australia, Mexico, Canada, Uruguay, Turkey, Argentina

7. Isolates CA TX SD ND MN LA FL NC Surveyed 75 isolates so far NE WI AL

8. Statistics  H O ranged from 0.014 to 0.973  H E from 0.166 to 0.742  11 loci are in Hardy-Weinberg equilibrium (P<0.05)

9. Preliminary Results  AMOVA showed most molecular variance within populations vs. among populations  Neighbor joining tree based on genetic distance

10. Tree Results 1.Group with little genetic differentiation forming between north, south and Texas populations (asexual pop.) 2.Northern aecial isolates form a group with greater genetic differentiation between isolates (sexual pop.) 3.California isolates forming own group with great genetic differentiation from other groups

11. Things yet to do….. Finish U.S. Isolates Screen Foreign Isolates Screen Markers on other Rust species Analyze data