WHEAT GENOTYPES THAT DEVELOP BOTH TAN NECROSIS AND EXTENSIVE CHLOROSIS IN RESPONSE TO ISOLATES OF PYRENOPHORA-TRITICI-REPENTIS

Wheat cultivars commonly develop either tan necrosis (nec) or chlorosis (chl) in response to infection by Pyrenophora tritici-repentis. We report, for the first time, wheat genotypes capable of developing both symptoms. Isolates of P. tritici-repentis can be classified on the basis of their ability to induce tan necrosis and/or extensive chlorosis. A selection of winter wheat cultivar Norstar and spring wheat line 6B699, tested to isolates from pathotypes 1 (nec+ chl+), 2 (nec+ chl-), 3 (nec- chl+), and 4 (nec- chl-), developed tan necrosis in response to nec+ isolates as well as extensive chlorosis in response to chl+ isolates. Both lines were sensitive to the Ptr-necrosis toxin. This finding suggests that tan necrosis and extensive chlorosis are controlled by different genes.