Identification of gene pairs involved in the incompatibility between an Eleusine isolate of Pyricularia oryzae and common wheat
S. ASUKE (1), I. Chuma (1), Y. Tosa (1) (1) Kobe University, Japan

Pyricularia oryzae, a causal agent of blast disease on various gramineous plants, shows host specificity at the plant genus level and cultivar level. To elucidate its mechanism, we started genetic analyses of the incompatibility between an Eleusine isolate of P. oryzae and common wheat. Segregation analysis of F1 progeny derived from a cross between an Eleusine isolate (MZ5-1-6) and Triticum isolate (Br48) suggested that MZ5-1-6 carries four avirulence (AVR) genes against wheat cultivar Chinese Spring (CS). One of the F1 progeny, 200R72, was selected and backcrossed with Br48. When the resulting BC1F1 progeny was sprayed onto CS, avirulent and virulent cultures segregated in a 1:1 ratio, indicating that an AVR gene (tentatively designated as A4) conditions the avirulence. To identify its corresponding resistance gene, F3 lines derived from CS x Hope (susceptible to 200R72) were inoculated with 200R72. Homozygous resistant : segregating : homozygous susceptible lines segregated in a 1:2:1 ratio (21:54:21, χ2=1.50), suggesting that a single gene is involved. This gene was considered to correspond to A4, and therefore designated tentatively as R4. In addition, complementation test revealed that one of the four AVR genes is the same as an AVR gene of Lolium isolates against CS. Consequently, we could identify two pairs of AVR genes and their corresponding resistance genes which are involved in the Eleusine isolate - wheat interaction.

Abstract Number: P17-488
Session Type: Poster