USE OF PROTEIN ELECTROPHORESIS TO QUANTIFY RESISTANCE OF FLAX GENOTYPES TO POWDERY MILDEW DISEASE

Ten flax genotypes were evaluated for powdery mildew resistance under field
conditions in 200212003 and L003/2004 growing seasons. Lines 42014, 421/43, and
421/60 showed the lowest ratings of disease severity, while line 110/3 showed the
highest rating. The remaining genotypes showed intermediate ratings ranging from
40.93 to 57.89%. Proteins of cultivar seeds were separated by SOS-PAGE, and the
obtained banding patterns were visualized by using the silver nitrate staining system.
Data for powdery mildew ratings and amounts of protein fractions were entered into a
computerized stepwise multiple regression. Using the predictors supplied by stepwise
regression, a four-factor model was constructed to predict powdery mildew severity. This
model showed that powdery mildew severity differences were due largely to the protein
fractions nos. 33, 31, 6, and 53, which accounted for 95.43% of the total variation in
severity ratings. This result indicates that SOS-PAGE of seed proteins may provide a
supplementary assay to field tests to distinguish quantitatively between powdery mildew
resistant or susceptible genotypes.