| Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe,is an important wheat disease worldwide, FHB is an important factor which affected yield and quality in wheat. In china, One quarter of the wheat growing area (about 6.7 million hectares) is being jeopardized by wheat FHB. The disease grain that is contaminated with mycotoxins produced by the fungus is a major safety concern to the health of human beings and livestock. In recent years, due to the gradual warming of the climate, the acreage of wheat scab showing a clear upward trend. There are many ways to control FHB, While crop management practices and chemical applications may reduce the damage to some degree, progress in developing genetically controlled resistant cultivars is critical for combating this disease.The host resistance is the most effective method for combating the disease. Scientists have tried to find new FHB resistance sources because of only a few sources of FHB resistance being available in the wheat-breeding program,so that how to fast and effective evaluate host FHB resistance is being ignored.In this study, Two components of host FHB resistance are used:resistance initial infection (type Ⅰ) and resistance to spread within the spike (type Ⅱ). It is generally accepted that type Ⅰ resistance is evaluated by spraying spikes with a macroconidial suspension to the point of runoff while type Ⅱ resistance is evaluated by injecting a macroconidial suspension into a single central floret of the spike using a hypodermic syringe. Another study showed that photosynthetic parameters may correspond to some of the physiological functions of resistant phenotype, which may be used to speculate on a variety of plants resistant to distinguish the response. In the early stage of the response, the difference between the different genotypes plants is difficult to detemine. Therefore, Finding an effective alternative is very important.To determine the effects of Fusarium graminearum inoculation on net photosynthetic rate and stomatal conductance of host flag leaves and to establish a alternative method to evaluate host FHB resistance, plants of the wheat FHB resistant genotypes L699 and its susceptible sister line L661 were artificially inoculated by injection and spraying and then measured the photosynthesis associated parameters using a modulated photosynthesis system and evaluated FHB with traditional methods. Fusarium graminearum infection FHB significantly reduced the net photosynthetic rate (Pn) and stomatal conductance (Gs) of L699 flag leaves, while the effects in L661 was very slight. However, FHB caused a significant reduction in the 1000-grain weight (KGW) and the total grain weights of single ears (SEW) in L661, but it did not cause significant reductions in those parameters for L699. The results of the resistance test indicated that L699 had significantly stronger resistance to FHB than L661 based on the visibly diseased spikelets (PDS), area under the disease progress curve (AUDPC), disease incidence (DI), and percentage of Fusarium-damaged kernels (PDK) recorded or counted. We conclude that the injection and spraying of Fusarium graminearum affected photosynthetic activity in the resistance response but had little effect in the susceptible response.This study indicated that the photosynthetic and yield indices would be useful for characterizing the resistance response and possibly be used as an alternative new method to estimate host FHB resistance. It’s a rapid, objective, efficient and accurate method to evaluate the FHB resistance of different wheat germplasm resources. This method laid a foundation for the screening of genetic resources and the important scientific problems which need to be solved urgently. |
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