Three new rust resistance genes in flax introductions

The genetics of resistance to flax rust (caused by Melampsora lini) in six flax (Linum usitatissimum) introductions from Argentina were investigated i n a series of crosses with single-gene lines for rust resistance. These int roductions proved resistant to the most virulent rust races in the North Am erican collection of M. lini. Segregating patterns in F-2 and BCF1 populati ons from crosses with the effective rust resistance genes indicated the pre sence of three resistance genes designated as A1, A2, and A3. These genes a re different from the rust resistance genes present in the 30 single-gene l ines used to differentiate the North American races of M. lini.