ARS | Publication request: Transfer of crown rust resistance from diploid oat Avena strigosa into hexaploid cultivated oat A. sativa

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2007
Publication Date: April 2, 2007
Citation: Rines, H.W., Carson, M.L. 2007. Transfer of crown rust resistance from diploid oat Avena strigosa into hexaploid cultivated oat A. sativa [abstract]. North American Cereal Rust Workshop, April 2-4, 2007, St. Paul, MN. p. 50.

Technical Abstract: New sources of resistance to crown rust, Puccinia coronata f. sp. avenae (Eriks.), the major fungal disease of cultivated oat, Avena sativa L. (2n = 6x = 42), are constantly needed due to frequent, rapid shifts in the virulence pattern of the pathogen. Crown rust resistance identified in the diploid oat A. strigosa (Schreb.) (2n = 2x = 14) accession CI6954SP was transferred into cultivated oat by two methods: direct 2x + 6x crosses with embryo rescue and use of an initial 2x + 4x cross. Two wild oat tetraploids, a crown rust resistant A. murphyi (Ladiz.) accession P12 and a susceptible A. insularis (Ladiz.) accession INS-1, were used in the 2x + 4x crosses. F1 progeny from both methods were colchicine doubled and fertile progeny crossed to the rust susceptible agronomic cultivar 'Ogle'. Resistant backcross derived lines were recovered by both methods. Although the 2x + 4x synthetic hexaploid method did not require the laborious discovery and rescue of an infrequent initial hybrid embryo of the direct cross, the direct cross method provided more rapid backcross recovery of plants with high fertility, full transmission of resistance, and desired plant and seed phenotypes. No resistance from A. murphyi P12 was detected in advanced generations when it was introduced either as a component of a synthetic hexaploid or in direct crosses to A. sativa, indicating suppression of its resistance in interploidy combinations. The introgressed resistance genes from the different methods might be incorporated into different host chromosome segments and thus allow tests of dosage effects on resistance expression.