Accumulation of lectins in cereal roots invaded by the cereal cyst nematode Heterodera avenae

Barley lectin and wheat germ agglutinin (WGA) accumulated in the roots of both resistant and susceptible cultivars of barley (Hordeum vulgate) and wheat (Triticum aestivum) following invasion by seeond-stage juveniles (J2) of the cereal cyst nematode Heterodera avenae Woll. In non-infected root the amounts of barley lectin and WGA decreased rapidly for 4 days after germination, whereas in nematode-infected roots their amounts dropped slowly. In H. avenae infected wheat roots the WGA precursor was observed 4-6 days after inoculation, whereas a barley-lectin precursor was not detected in barley roots. These phenomena were also observed in seedlings treated with abscisic acid and jasmonic acid. Immunohistological studies revealed the presence of WGA in epidermal cells of the root tip and in the nematode feeding-site (ayncytium) region. Commercial WGA bound to the cuticular surface of H. avenae J2 in vitro. WGA did not accumulate in wheat roots inoculated with J2 of another cereal cyst nematode, H. latipons, and the commercial WGA did not bind to the J2 surface in vitro. The lectins are suggested to play a role in the H. avenueplant interaction.