| Gray leaf spot(GLS)has become a major disease in China's corn production.Breeding resistant varieties is one of the effective ways to control corn gray spot.In this study,the disease-resistant inbred line Qi 319,the susceptible inbred line ? 478,and the two parental lines containing the first chromosome(bin1.02)target QTL interval were used as experimental materials.The artificial inoculation of Cercospora cerevisiae was carried out.The propagation process of pathogenic bacteria in anti-inductive materials at different stages before and after inoculation was observed by optical microscope.The changes of tissue cell structure in anti-inductive materials before and after inoculation were observed by transmission electron microscopy,and the resistance of maize to gray spot disease tissue cells was revealed.Mechanism: The physiological mechanism of maize resistance to gray spot was revealed by analyzing the differences in enzyme activities and soluble sugars in leaf tissues before and after inoculation.The main results of this study are as follows:1.The Qi 319,Ye 478 and fragment substitution lines were observed by transmission electron microscopy at 0 d,3.5 d,15 d and 35 d after inoculation.The susceptible material was more damaged than the diseased material leaf mesophyll cells,and the starch in the susceptible material.The granules tend to increase gradually,and the starch granules in the disease-resistant materials show a constant or slightly decreasing trend.It indicated that the disease-resistant material could resist the damage of the mesophyll cells caused by the infection of Cercospora cerevisiae,and the pathogen infection had little effect on the corn sheath cells.2.The Qi 319,Ye 478 and fragment substitution lines were observed by transmission electron microscopy at 0 d,3.5 d,15 d and 35 d after inoculation.The susceptible material was more damaged than the diseased material leaf mesophyll cells,and the starch in the susceptible material.The granules tend to increase gradually,and the starch granules in the disease-resistant materials show a constant or slightly decreasing trend.It indicated that the disease-resistant material could resist the damage of the mesophyll cells caused by the infection of Cercospora cerevisiae,and the pathogen infection had little effect on the corn sheath cells.3.The POD enzyme activity,SOD activity,CAT enzyme activity and MDA content ofmaize leaves at 0 d,3.5 d,15 d and 35 d after inoculation were determined by using the susceptible material Ye 478 and resistant fragments.The results showed that the anti-inductive materials played a role in POD enzyme activity,SOD activity,CAT enzyme activity and MDA content after infection by Cercospora cerevisiae.The activity of POD enzyme was 3.5 d,the activity of POD in the treatment group was significantly higher than that in the control group.After 15 days,the activity of POD enzyme increased steadily and slightly,and the activity of POD enzyme in the resistant disease replacement material was significantly higher than that of the susceptible material.Better than susceptible materials.The activity of SOD enzyme in the treated group was significantly higher than that in the control group after 15 days,and there was a certain relationship between the activity of SOD enzyme and the disease resistance of the resistant material.It indicated that the activity of SOD enzyme in the disease-resistant substituting material was high,which was strong against the invasion of gray spot disease,which delayed the damage of the pathogen to the host plant and showed certain disease resistance.The activity of CAT enzyme was significantly higher than that of the control group after 35 days,and the increase of CAT enzyme activity of resistant fragments was significantly higher than that of susceptible materials,indicating that the maize resistant fragments were replaced.There is a certain relationship between the disease resistance of the material and the CAT enzyme activity.The anti-disease substitution material has high CAT enzyme activity,which is strong against the invasion of gray spot disease,delays the damage of the pathogenic bacteria to the host plant,and shows certain disease resistance.The content of MDA changed after 3.5 days,and the MDA content of the susceptible material in the treated group was higher than that of the disease resistant material,and the MDA content of the susceptible material was significantly higher than that of the resistant fragment replacement material.The damage of the leaf cell membrane of the diseased material is more serious than that of the disease-resistant fragment replacement material.There is a certain relationship between the MDA content and the degree of cell membrane damage in corn anti-inductive materials.4.The soluble sugar content of corn stalks at 0 d,3.5 d,15 d and 35 d after inoculation was determined by the Ye 478 and resistant fragments of the susceptible material.The results showed that the resistance of the genus Corydalis was infected.The change ofsoluble sugar content in the material had a certain relationship with the degree of pathogenesis in the field.At 3.5 days,the soluble sugar content of anti-inductive materials in the treatment group decreased.The result of insufficient supply of sugar in the host due to the invasion of pathogens. |
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