Genetics of resistance to Amphorophora rubi (Kalt.) in the raspberry II. The genes A2–A7 from the American variety, Chief

Abstract

The American raspberry variety Chief is shown to carry three dominant genes, A5, A6 and A7, each capable of conferring strong resistance to Amphorophora rubi strain 1.Chief also carries three genes, A2, A3 and A4, for resistance to A. rubi strain 2. A2 is a dominant gene conferring full resistance by itself; A3 and A4 are dominant complementaries, neither gene by itself having any effect on resistance. A5 is linked with either A3 or A4 with a crossover value of 10%.The gene A1 from Baumforth A, which confers resistance to strains 1 and 3, when combined with A3 gives resistance to strain 2 also. Thus the three strains of A. rubi at present recognized on raspberries in Britain can be controlled by using either the combination A1A2 or A1A3.