| Maize as the largest crop in China, it played an important role in food and industrial materials, occupied an important position in the national economy, the maize production situation directly related to the strategy of the food safety in our country. In our country, especially in the southwest region, due to the high temperature, high humidity in the maize growing period, BLSB has become one of the main diseases in the major maize producing areas, it has seriously affected and restricted in the yield and quality improvement of the maize. As Banded leaf and sheath blight (BLSB) in maize is more and more serious, commonly prevention and control measures can’t meet the needs of the production. Conduct in-depth study about the mechanism of resistance to BLSB of maize, explore and make use of the germplasm which with genetic disease resistance is the effective method to control this disease.In this study,285maize inbred lines were used as the research materials which were domestic commonly used on maize breeding and production. Screening for3years in4environments in order to find good stability of BLSB resistance source materials in maize, provide material supports for BLSB resistance genetic studies; Analysis the evaluation results of stability and correlation with the environment, in order to search the cause of the BLSB in maize occurred and developed from the environmental conditions; Compare the differences between4environments of height plant, height of main ear position, height of disease spot, internodes number at the bottom of the ear, the ratio of main ear height and plant height, the ratio of disease spot height and plant height, the ratio of disease spot height and main ear height, internodes distance at the bottom of the ear(the ratio of main ear height and internodes number at the bottom of the ear) and disease index in3years and analyze the correlation between the various indicators, for the choice of evaluation index and resistance, breeding resistance to sheath blight in maize inbred lines from the plant type to provide the reference data;10inbred lines of peroxides activity was measured; through the analysis of variance and correlation analysis comparison between inbred lines, health and disease among the plant enzyme activity change rules, in order to select evaluation index from the aspects of physiological and biochemical resistance provides some references; all the published QTL results of BLSB in maize were collected, a meta-analysis was carried out to get the consistency domain, select out the disease-resistant hot spots, To provide support for marker-assisted selection breeding, fine set the main effected QTL And in-depth development of genetic research. The main results were summarized as followed:1. After field resistance identification in3years for4environment, the disease index highest shall prevail, no immune or highly resistant and resistant lines was found.only one inbred line was resistant material, account for0.35%of the285lines. The lines of susceptible and highly susceptible were17for5.96%and267for93.68%, respectively. The results indicated that most of the inbred lines did not have good resistance to BLSB of maize, and the germplasm of high resistance were extremely poor. After two years of resistance identification, NL275(PA31) was found it had a relatively stable of the resistance, but the number of this inbred lines is less, and just had two year’s result, need to be further identified.2. Analysis of variance showed that,9kinds of measuring indexes between environment and genotype showed significant or extremely significant differences in285inbred lines, suggested that BLSB of maize is influenced by environment and genotype; Correlation analysis showed that, internodes distance at the bottom of the ear with the height of the disease spot and the ratio of main ear height and plant height had no significant correlation, others all showed extremely significant between each other measurements. Disease index showed extremely significant correction with the other eight kinds of measurements, specially, the height of the disease spot and the ratio of disease spot and plant height with the disease index has a highest level in significant correlation, respectively, both of the correlation is0.64. So author thought, all the indexes can be used as the measure of maize inbred lines in BLSB resistance and the ratio of the height of disease sport and main ear position can be used as the main evaluation.3. After inoculation of AG1-IA, POD activity showed significant differences between sampling time in ten inbred lines; POD activity showed a tendency of up-down-up in the leaves of inoculated plant, and there was no significant alteration in the leaves of health plant. Maize inbred lines with different level of resistant were closely related to the change of POD activity, it shown as:(1) the disease index in maize inbred lines was lower correspondingly when the variations in POD activity were larger, the peak of POD activity appeared earlier and the POD activity was higher before inoculation.(2) There was the highest significant negative correlation between POD activity in leaves after inoculation in0hours and the disease index. So the author thinks it can be used as a physiological indicator of the degree in disease resistance.4. Our purpose was to identify the genomic regions of maize in the control of BLSB resistance, A meta-analysis was carried out using57quantitative trait loci (QTL) from5 studies to propose meta-QTL (MQTL) on a high-density genetic linkage map (IBM2neighbors2008). Fifteen MQTL were found for BLSB resistance, mainly located on chromosomes2,4,6,8,9and10. The BLSB MQTL were clustered on five chromosome regions, bins2.02,2.06,6.02,9.01and9.04. Two MQTLs were focused on chromosome region bin2.06, there were six QTLs that come from different environmental background integrated into two MQTL (MQTL2and MQTL3), MQTL2has a minimum confidence interval (1.23cM); Also found that bin3.05which has loci of BLSB resistance and bin6.01which has one MQTL both with multiple disease resistance gene loci. |
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