The Occurrence of Cell Wall Appositions in Flag Leaves of Spring Wheats, Susceptible and Partially Resistant to Wheat Leaf Rust

Abstract

AbstractIn two experiments, the presence of cell wall appositions in flag leaves of spring wheat genotypes susceptible and partially resistant to wheat leaf rust was studied. More cell wall appositions were observed near aborted infection structures than in estabhshed colonies. There was not a marked difference in the number of cell wall appositions per colony between susceptible and partially resistant genotypes. More cell wall appositions per unit area colony were present in partially resistant genotypes. It was concluded that the low number of cell wall appositions could not be responsible for the observed difference in colony size between susceptible and partially resistant genotypes. Partial resistance in wheat to wheat leaf rust can be divided into two phases. The first phase is pre‐haustorial and results in a reduction of the number of colonizing infection structures. In the second phase a post‐haustorial retardation of fungal growth rate occurs. The latter appears to be the more important phase.