PHYSIOLOGICAL AND BIOCHEMICAL BASES OF RESISTANCE OF FLAX (LINUM USITATISSIMUM L.) TO PASMO

This study preliminarily aimed to discuss the relationship between the dynamic changes in physiological and biochemical indexes of flax (Linum usitatissimum L.) resistant and susceptible varieties (lines) and their resistance to pasmo pathogen (Septoria linicola), and provide the basis for exploring the mechanism of disease resistance in flax. The activities of defensive enzymes and the content of malondialdehyde (MDA) in the leaves of two flax cultivars, one resistant and another susceptible to pasmo, were detected at different stages after inoculation with the pathogen. The results showed that in the early stages of pathogen infection, the activity of superoxide dismutase of resistant varieties (lines) was significantly higher than that of susceptible varieties (lines). In addition, the changes in peroxidase, catalase, and polyphenol oxidase activities in the inoculated leaves of different flax varieties positively correlated with their varied resistance to pasmo, but with no significant difference between resistant and susceptible varieties. However, the changes in phenylalanine ammonialyase activity in the two cultivars were assumed to be negatively correlated with their resistance to pasmo. For most of the stages after inoculation with S. linicola, the changes in the MDA content were negatively correlated with host resistance, but with no significant difference between resistant and susceptible varieties.