Postpenetration Phenomena in Wheat Cultivars with Low Receptivity to Infection byPuccinia graminisf. sp.tritici

Publisher Website
Google Scholar
Abstract
The characteristic low receptivity of wheat (T. aesitivum) cultivars ''Marquis'', ''Lee'', ''Thatcher'' and Idaed 59'' to infection by P. graminis f. sp. tritici, as shown by the number of uredia in adult plants, was constant under different environments and with several cultures of diverse races identified as virulent on seedlings of these cultivars. Fungal penetrants of putative virulent cultures interacted either compatibly or incompatibly in all cultivars with low receptivity. Compatible colonies in cultivars with low receptivity were significantly smaller than those in plants of highly receptive cultivars ''Purdue 5481C1'' and ''Baart''. In ''Lee,'' ''Thatcher'', and ''Idaed 59'', the proportion of compatible to total penetrants reflected the reduced number of uredia produced on these hosts. In ''Marquis'', the proportion of compatible penetrants did not differ significantly from that in ''Purdue 5481C1''. The reduced colony size of compatible penetrants observed histilogically at 65 and 96 h in all hosts with low receptivity was generally reflected by the smaller uredia that appeared later. Highly incompatible colonies in cultivars with low receptivity were smaller than compatible ones and were associated with collapsed host cells. Thus, these incompatible penetrants produced a hypersensitive response similar to that associated with specific gene resistance and presumably failed to produce uredia.