1. Crown rust resistance of oat germplasm from the ARS- Aberdeen program J. M. Bonman (1), D.E. Obert (1), E. W. Jackson (1), S.A. Harrison (2) and M. L. Carson (3). (1)USDA-ARS, Small Grains and Potato Germplasm Research Unit, 1691 S. 2700 W., Aberdeen ID 83210; (2) Louisiana State University, AgCenter Agronomy Department, 104 MB Sturgis Hall, Baton Rouge, LA 70803; (3) USDA-ARS Cereal Disease Laboratory1551 Lindig Ave., St. Paul, MN 55108.

2. Where is Aberdeen? University of Idaho Research and Extension Center, Aberdeen, ID

3. Background Previously the program targeted the Intermountain West– objective was high yield and quality Currently a need to make Aberdeen material more widely useful by incorporating disease resistance

4. Objectives  Characterize crown rust resistance within Aberdeen cultivars and breeding lines:  Field reactions in “hot spot” locations (Castroville, TX; Baton Rouge, LA)  Seedling resistance to many isolates (CDL)  Field reactions to single isolates (isolated plots in Aberdeen, ID)  Assess partial resistance of selected materials in greenhouse inoculations with compatible isolates

5. Test lines and cultivars

6. Check cultivars  CDC Boyer  IA98822-2

7. ID field plots for single isolate tests

8. Single isolate tests Experimental units = single hills

9. Field tests— naturally occurring inoculum Entry Field Test Location LouisianaTexas DLA (%)Class a DLA (%)Class CDC Boyer (R check) 13.3check16.7check 99Ab11862 18.3R20.0R IA 98822-2 35.0R11.7R 99Ab12179 36.7R16.7R 99Ab11813 56.7S26.7R 95Ab11439 50.0S43.3R Monida 31.7R65.0S Monico 32.5R66.7S 99Ab11468 53.3S55.0S 89Ab3840 66.7S50.0I 94Ab6965 66.7S56.7S 98Ab7085 61.7S63.3S 99Ab11685 56.7S73.3S 99Ab11899 63.3S66.7S 99Ab11787 65.0S66.7S Maverick 65.0S68.3S Ajay 80.0S55.0S Otana 80.0S56.7S 99Ab12402 68.3S70.0S Lamont 80.0S63.3S 99Ab12687 76.7S70.0S Provena (S check) 75.0check73.3check 98Ab7399 80.0S70.0S 95Ab12847 76.7S S a R = not significantly different from the resistant check CDC Boyer by Dunnett's test (p = 0.05) S = not significantly different from the susceptible check Provena by Dunnett's test (p = 0.05) I = intermediate

10. Field tests— single isolate evaluations R = not significantly different from the resistant check CDC Boyer by Dunnett's test (p = 0.05) S = not significantly different from the susceptible check Provena by Dunnett's test (p = 0.05) I = intermediate Entry Specific Isolates 98MNB24503MN111CR185 DLA (%)Class a DLA (%)ClassDLA (%)Class CDC Boyer (R check)2.5check5.4check1.0check 99Ab11862 0.9R12.6R0.3R IA 98822-2 4.3R4.1R3.0R 99Ab12179 10.5R13.6R2.3R 99Ab11813 0.4R13R1.4R 95Ab11439 8.8R17R42.0I Monida 22.0R22I5.3R Monico 35.0S29S97.5S 99Ab11468 23.8R29S15.0R 89Ab3840 27.5S15.6R27.5R 94Ab6965 52.5S26.2S87.5S 98Ab7085 37.5S33S97.5S 99Ab11685 8.3R12.6R5.3R 99Ab11899 31.3S26S95.0S 99Ab11787 23.8R40S100.0S Maverick 40.0S31S72.5S Ajay 23.8R27S32.5R Otana 25.0S37S100.0S 99Ab12402 43.3S27S100.0S Lamont 30.0S33S97.5S 99Ab12687 22.5R29S90.0S Provena (S check)47.5check38check100.0check 98Ab7399 47.5S44S100.0S 95Ab12847 15.8R23S72.5S

11. Greenhouse tests versus a spectrum of isolates Entry Resistance spectrum (%) a CDC Boyer (R check)100 99Ab1186249 IA 98822-262 99Ab1217960 99Ab1181357 95Ab11439100 Monida100 Monico100 99Ab11468100 89Ab384080 94Ab6965100 98Ab708596 99Ab1168570 99Ab1189998 99Ab11787100 Maverick100 Ajay100 Otana100 99Ab12402100 Lamont98 99Ab1268794 Provena (S check)100 98Ab7399100 95Ab12847100 a Percent compatible P. coronata isolates tested at the Cereal Disease Laboratory, n = 48

12. Provena 99Ab11862 95Ab11439 99Ab11813 99Ab12179 Leaf segment inoculation technique:

13. Greenhouse test for partial resistance a Numbers within a column followed by the same letter are not significantly different by Tukey’s HSD test. Four isolates tested, no significant isolate by genotype interaction detected. GenotypeDLA (%) a FDNA (pg/mg oat tissue) Provena17.1 a1208 a 99Ab1186213.6 ab623 b 99Ab1217910.6 bc696 b 95Ab114399.2 c638 b

14. Conclusions Most of the Aberdeen cultivars and lines are highly susceptible to crown rust A few lines showed less disease in field trials –specific resistance to some isolates –partial resistance to compatible isolates in the greenhouse, thus field response probably due to partial resistance