FORMATION OF WALL OPENINGS IN ROOT-CELLS OF ARABIDOPSIS-THALIANA FOLLOWING INFECTION BY THE PLANT-PARASITIC NEMATODE HETERODERA-SCHACHTII

The induction and differentiation of feeding structures (syncytia) of the cyst nematode Heterodera schachtii in roots of Arabidopsis thalian a is accompanied by drastic cellular modifications. We investigated th e formation of cell wall openings which occurred during syncytium diff erentiation. At the beginning of syncytium induction, a callose-like l ayer was deposited inside of the wall of the initial syncytial cell (I SC). First wall dissolutions developed by gradual widening of plasmode smata between the ISC and neighbouring cells. As a general thickening of syncytial cell walls blocked existing plasmodesmata, other large op enings were formed by enzymatic dissolution of intact walls by putativ e cellulase activity.