Gene Analysis of Mutants Resistant to Alternaria alternata Strawberry Pathotype Selected from Calliclones of Strawberry Cultivar Morioka-16

Abstract

Gene analysis of the disease-resistant selections, 'M16-AR 1', 'M16-AR 2' and 'M16-AR3' was made. These calliclones were derived by culturing the shoot apices of 'Morioka-16' which is susceptible to Alternaria alternata strawberry pathotype. The analysis is based on the results of disease reactions of their progenies from selfing (S₁) and hybrid crosses (F₁)with 'Morioka-16' and with 'Hokowase', a recessive homozygote with respect to the susceptible gene. The following results were obtained:
S₁ progenies of each line showed resistance to the pathogen. F₁ progenies of reciprocal crosses between 'M16-AR 1, 2 or 3' × 'Morioka-16' (heterozygous in relation to the susceptible gene) and between 'M16-AR 1, 2 or 3' × 'Hokowase' (homozygous recessive in relation to the susceptible gene) resulted in the following segregation ratios of susceptibility (S) and resistance (R) to the pathogen.
'M16-AR 1, 2 or 3' × 'Morioka-16' and vice versa l (S) : 1 (R)
'M16-AR 1, 2 or 3' × 'Hokowase' and vice versa 0 (S) : 1 (R)
The results described above suggest that the genotype of each of the three lines exhibited variation from the genotype of 'Morioka-16', namely, heterozygote to recessive homozygote with respect to the susceptible gene.