STEROLS OF IMMUNIZED POTATO-TUBERS

It is experimentally demonstrated in the present work that treating potato tubers (Solanum tuberosum L.) with low concentrations (of the order of 10(-8) M) arachidonic acid significantly lowers the content of free sterols in treated tissues of the host plant and alters their qualitative composition, which leads to total inhibition of sporulation of the late blight agent, Phytophthora infestans (Mont.) de Bary. The inhibiting action of immunizing concentrations of AA was preserved only during the immunization period. On the other hand, treatment with high concentrations of AA (of the order of 10(-4) M) did not exert such action. The content of sterols did not increase, and the ratio of separate components did not change, a situation that was accompanied by loss of blight resistance.