INHERITANCE OF CROWN RUST RESISTANCE IN 4 ACCESSIONS OF AVENA-STERILIS L

Genetic resistance in common oat, Avena sativa L., provides an effecti ve means of controlling crown rust, caused by Puccinia coronata Cda. f . sp. avenae Eriks. Four Avena sterilis L. accessions (IB 1487, IB 240 2, IB 2465, and IB 3432) were selected for a genetic study based on lo w disease reaction to 15 isolates of crown rust and ease of hybridizat ion to common oat. Crosses were made to determine the mode of inherita nce of the resistance in each accession and to detect the linkage rela tionship of the resistance genes with several known crown-rust resista nce genes. The accessions were crossed to the susceptible common oat l ine Rodney 0, intercrossed among themselves, and crossed to six Lines, each with a single gene for crown rust resistance: Pc38, Pc56, Pc58, Pc61, Pc63, and Pc68. In a greenhouse, the F-2 populations were evalua ted for seedling reaction after inoculation of the first leaf with cro wn rust isolate CR 13. Each accession had a single incompletely domina nt or dominant gene conferring resistance, and genes were designated a s Gene A in IB 1487, Gene B in IB 2402, Gene C in IB 2465, and Gene D in IB 3432. Gene A is allelic or closely linked to Pc56. Genes B and C are allelic or closely linked to Pc68. Having not been described prev iously, Gene D may be a useful addition to existing germplasm.