INFLUENCE OF GRAIN APHID, SITOBION-AVENAE (F), ON GLIADIN AND ESTERASE ISOENZYME PATTERNS IN SEEDS OF 2 WINTER-WHEAT CULTIVARS

The ears of two winter wheat cultivars, 'Regina' and 'Zdar', were arti ficially infested at anthesis by the grain aphid, Sitobion avenae (F.) , to evaluate aphid influence on gliadin and esterase isoenzyme patter ns of seeds. Seeds from infested (IS) and noninfested (CS) ears of bot h cultivars contained at milk (immediately after aphids had been remov ed) and fully ripe growth stages of plants cultivar-specific gliadin p atterns and two main groups - slowly and fast migrating esterase isoen zymes. There were no differences in the qualitative composition of gli adins and isoenzymes between aphid-damaged and nondamaged seeds. In IS of both cultivars, a decrease of gliadin intensity was observed, corr esponding with their significant (P < 0.01) lower weight. No visible c hanges were detected in the activity of slowly migrating isoenzymes be tween IS and CS despite the differences in the seed size. Intensity of fast migrating isoenzymes in IS at milk ripe stage was lower than tha t in CS, but this decrease was compensated till the fully ripe stage. Positive correlation between seed weight and intensity both of ''slow' ' and ''fast'' esterase isoenzymes has been experimentally confirmed. That is why S. avenae feeding on ears at anthesis seems to increase ac tivity of ''slow'' isoenzymes and plant ability to compensate decrease of ''fast'' isoenzymes till the fully ripeness stage.