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GrainGenes Reference Report: PHY-91-702

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Reference	PHY-91-702
Title	Sensitivity of wheat genotypes to a toxic fraction produced by Cephalosporium gramineum and correlation with disease susceptibility
Journal	Phytopathology
Year	2001
Volume	91
Pages	702-707
Author	Rahman M Mundt CC Wolpert TJ Riera-Lizarazu O
Abstract	Summary: Cephalosporium stripe is an important disease of winter wheat (Triticum aestivum) in several areas of the world, especially where stubble mulch and early seeding are practiced to maintain soil moisture and prevent erosion. We developed a procedure to mass-produce a toxic fraction produced by Cephalosporium gramineum through a modification of the method of Kobayashi and Ui. Exposure of excised wheat leaves to a concentration of 60 microliter/ml of the toxic fraction for 72 h produced distinct wilting symptoms that allowed us to distinguish toxin-sensitive wheat genotypes in a repeatable manner. Twenty wheat genotypes belonging to four distinct germ plasm groups (common, club, durum, and synthetic) were evaluated. Variation in toxin sensitivity of wheat genotypes was mostly at the level of the germ plasm group, and all differences among the four germ plasm groups were highly significant (P < 0.001) based on linear contrasts. Seventeen winter wheat genotypes representing the common, club, and durum germ plasm groups were planted in C. gramineum-infested fields at two locations. The logarithm of the percentage of tillers showing whitehead symptoms at each of the two locations was significantly (P < 0.0001) correlated with wilting symptoms measured by the toxin assay (r = 0.80 and 0.84). The common wheat genotypes were all sensitive to the toxic fraction, but showed a substantial range of disease reactions in the field. However, we found no case of a toxin-insensitive genotype being susceptible in the field. These results suggest that toxin insensitivity may be an important mechanism of resistance to Cephalosporium stripe, but that other mechanisms are operative as well. The toxin assay may be useful as an initial screening procedure to reduce the number of genotypes to be tested in the field
Keyword	[ Hide all but 1 of 44 ] assay cephalosporium common wheat correlation disease disease resistance disease susceptibility distinguish durum erosion exposure field fraction genetic variation genotype germ germ plasm hymenula cerealis insensitivity mechanism method modification moisture mycotoxins pathogenicity plant pathogenic fungi resistance screening sensitivity soil soil moisture stubble susceptibility symptoms tillers toxin triticum triticum aestivum wheat genotypes wheat leaves wilting winter winter wheat world

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