Inheritance of resistance to Fusarium graminearum in wheat

To study the inheritance of resistance in wheat to Fusarium graminearum, si x resistant cultivars from China were crossed to two susceptible cultivars. The parents and their progenies were evaluated in the greenhouse for resis tance to the spread of scab within a spike. A central floret was inoculated by injecting a droplet of inoculum at the time of anthesis. Inoculated pla nts were kept in a moist chamber for three subsequent nights. The proportio n of scabbed spikelets was recorded six-times from 3-days to 21-days after inoculation, and the area under the disease progress curve (AUDPC) was calc ulated from these proportions. One to three genes, depending on the cultiva r, conditioned resistance to scab as reflected by the AUDPC. A simple addit ive-dominance effect model fitted the segregation data for 8 of the 11 cros ses. Dominance and epistatic effects were significant in a few crosses. The se effects increased resistance in some crosses but decreased resistance in others. However, relative to additive effects, dominant and epistatic effe cts accounted for only a small portion of the genetic effects in the popula tions evaluated. The importance of additive effects means that it should be possible to accumulate different genes to enhance resistance to scab in wh eat.