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 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

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

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

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

Test lines and cultivars

Check cultivars  CDC Boyer  IA

ID field plots for single isolate tests

Single isolate tests Experimental units = single hills

Field tests— naturally occurring inoculum Entry Field Test Location LouisianaTexas DLA (%)Class a DLA (%)Class CDC Boyer (R check) 13.3check16.7check 99Ab R20.0R IA R11.7R 99Ab R16.7R 99Ab S26.7R 95Ab S43.3R Monida 31.7R65.0S Monico 32.5R66.7S 99Ab S55.0S 89Ab S50.0I 94Ab S56.7S 98Ab S63.3S 99Ab S73.3S 99Ab S66.7S 99Ab S66.7S Maverick 65.0S68.3S Ajay 80.0S55.0S Otana 80.0S56.7S 99Ab S70.0S Lamont 80.0S63.3S 99Ab S70.0S Provena (S check) 75.0check73.3check 98Ab S70.0S 95Ab S 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

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 99Ab R12.6R0.3R IA R4.1R3.0R 99Ab R13.6R2.3R 99Ab R13R1.4R 95Ab R17R42.0I Monida 22.0R22I5.3R Monico 35.0S29S97.5S 99Ab R29S15.0R 89Ab S15.6R27.5R 94Ab S26.2S87.5S 98Ab S33S97.5S 99Ab R12.6R5.3R 99Ab S26S95.0S 99Ab R40S100.0S Maverick 40.0S31S72.5S Ajay 23.8R27S32.5R Otana 25.0S37S100.0S 99Ab S27S100.0S Lamont 30.0S33S97.5S 99Ab R29S90.0S Provena (S check)47.5check38check100.0check 98Ab S44S100.0S 95Ab R23S72.5S

Greenhouse tests versus a spectrum of isolates Entry Resistance spectrum (%) a CDC Boyer (R check)100 99Ab IA Ab Ab Ab Monida100 Monico100 99Ab Ab Ab Ab Ab Ab Ab Maverick100 Ajay100 Otana100 99Ab Lamont98 99Ab Provena (S check)100 98Ab Ab a Percent compatible P. coronata isolates tested at the Cereal Disease Laboratory, n = 48

Provena 99Ab Ab Ab Ab12179 Leaf segment inoculation technique:

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 99Ab ab623 b 99Ab bc696 b 95Ab c638 b

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