Molecular Study on Some of Physiological Changes in Susceptible and Tolerant Genotypes of Maize in Response to Maize Dwarf Mosaic Virus Infection

In this work, the changes of antioxidant enzymes activity were studied by spectrophotometry method and expression level of NPR1، FKBP، Chlorophyll a-b binding protein andMetallothionein-like protein genes in two tolerant and susceptible genotypes of maize in response to maize dwarf mosaic virus was investigated by qRT-PCR method. Experiment was done in green-house condition by mechanical inoculation and sampling was carried out at different time intervals (0, 1, 9, 24, 72) hors post inoculation (hpi). The results showed a significant increase of peroxidase activity in the tolerant genotype at all sampling times when compared to the susceptible genotype. The highest increase of peroxidase enzyme was recorded at 24hpi for both genotypes in comparison to the control plants, but after 72hpi the rate of peroxidase enzyme was reduced. Catalase enzyme activity was significantly reduced at all sampling time after virus inoculation when compared to the control plants. Gene expression analysis showed that the related expression of NPR1 and MT-LP genes were increased in both genotypes but this increase was significant only in the tolerant genotype. The expression level of FKBP gene in the tolerant genotype increased at the early times after virus inoculation and was decreased more rapidly than susceptible cultivar. The expression changes of Chlorophyll a-b binding gene plants significantly reduced in susceptible plants compared to the control plants. Changes in the antioxidant enzyme activity and gene expression could be used as bio-markers for virus-plant interaction studies and the associated markers may be selected for plant resistance to viral disease