| Fusarium head blight(FHB)is extremely harmful and destructive as one of the major wheat diseases in the humid and semi-humid areas of the world.Wheat infected by Fusarium graminearum leads to the production of toxins such as deoxynivalenol and the infection of head blight,resulting in a serious reduction in the yield and quality.The resistance types can be divided into five categories:resistance against initial infection(Type ?),resistance to pathogen spreading in infected tissue(Type II),resistance to kernel infection(Type ?),resistance to toxins in ears by decomposing them(Type IV)and tolerance to toxin(Type V),among which the kernel resistance is less studied but the research on resistance is of great significance.Fusarium damaged kemel(FDK)was always used to measure the kernel resistance.However,single-flowering inoculation during flowering period is more for assessing Type ? that kernels of resistant materials appear more serious than the susceptible.It is hard to count the FDK when kernel surface is good with broken internal damage and high toxin.To reduce the impact of Type II and evaluate kernel resistance independently,we have adopted a new kernel resistance research system.On the 5th,15th,and 25th days after the flowering stage,we inoculated each flower on the spikelets to observe the response to Fusarium graminearum in grain of resistant and susceptible material during grouting stage and sampling at the same time point.Field trials and vitro tests were used to answer the question of how to measure it from perspective of pathogens and plants.Results of kernel resistance studies are inconsistent with the Type ? performance that no significance difference between the resistant materials and the susceptible materials.Measured indicators include identification of phenotypes of living plants,shrinkage of seeds after inoculation,mycelial growth on seed surface after inoculation,growth rate of mycelium in vitro tests,toxin content measured by Elisa,number of conidia counted by hemocytometer.The major results are as follows:1.Inoculating in different grouting periood can lead to sterile lemma of materials turning brown.5th and 15th days after flowering are better choice to inoculate than the 25th.Some resisitant materials appered the high percentage of infection spikelet like Sumai3,which inoculated on 5th and 15th after flowering can up to 83.3%and 88.9%.2.Living inoculation in different grouting period could cause the kernel to shrivel and turn white.Many small holes and potholes existed on the surfuce of kernels inoculated on the 5th and the 15th days after flowering.This phenomenon occurs not only in susceptive materials but also in resisitant materials.3.Hyphal will distributed on embryo,pappus and crease of which kernels inoculated on the 5th day after flowering.There are many mycelium in the potholes and the damage of some resistant materials like Sumai3 and NIL-3 are worse.4.Kernels of all materials in different grouting period can promote the growth of mycelium and the matural kernels have the least promotion effect.5.Kernels of all materials in different grouting period can significantly improve the spore production of gibberella and some resisitant materials like Sumai3 and Ning7840 have great inducibility.6.Kernels of all materials in different grouting period can induce the production of DON effectively and some resistant materials like Sumai3 and NIL-3 and Ning7840 have better inducibility than susceptive materials.In different grouting period,the amout of DON induced by resisitant materials is more than the DON induced by susceptive materials.We found that the toxin content was positively correlated with the groutig period of kernel.7.The treatmet with Fusarium graminearum can reduce the germinating percentage and materials can all respond to the Fusarium graminearum. |
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