INHERITANCE OF RESISTANCE TO NET BLOTCH IN BARLEY. II. GENES CONDITIONING RESISTANCE AGAINST RACE W.A.-2

Abstract

Resistance to race W.A.-2 of net blotch has been found to be conditioned by a single gene, designated Pt a , in each of the three varieties originating from Manchuria: Manchuria (C.I. 2330), Ming (C.I. 4797) and Tifang (C.I. 4407-1). Resistance to the same race, exhibited by each of two varieties of Ethiopian origin (C.I. 5791 and C.I. 9819), has been found to be conditioned by duplicate genes, one of which is allelic to Pt a . The relationship of the second gene has not been determined. It was concluded that Pt a , differs from the three genes, viz. Pt 1 , Pt 2 , and Pt 3 , previously identified in California, and was shown to segregate independently of the two-row characteristic.Differences were noted in the dominance relationships of gene Pt a contributed by the Manchurian varieties. This indicates differences in the genetic background of the sources of resistance from this area which would likely detract from their value as parents in any Western Australian breeding program.