Figure 3.

Slp1 Binds Specifically to Chitin Oligosaccharides.

(A) Affinity precipitation experiments showing that Slp1 coprecipitates with insoluble crab shell chitin and chitin beads and was detected in the insoluble pellet fraction (P) following SDS-PAGE and Coomassie blue staining. Slp1 did not precipitate with other insoluble polysaccharides, including chitosan (deacetylated chitin) or the plant cell wall polysaccharides xylan and cellulose. Instead, Slp1 remained in the nonprecipitated supernatant fraction (S) after incubation with these polysaccharides.

(B) Slp1 does not provide protection from hyphal tip hydrolysis by chitinase enzymes. Micrographs of T. viride spores taken 24 h after addition of either water or crude extract of tomato leaves containing intracellular basic chitinases (ChiB). Pretreatment with 10 μM Avr4 prevented hydrolysis of T. viride hyphal tips by basic chitinase (Avr4 and ChiB), whereas pretreatment with 10 μM Slp1 (Slp1 and ChiB) did not. Bars = 10 μm.