Effect Of Temperature On MCMV And Corn Lethal Necrosis Disease

As a major food crop,corn is endangered by many viruses.In the field investigation,the research team found corn plants with various symptoms such as mosaic,mottle,and yellowing.During the laboratory test,maize chlorotic mottle virus was infested separately in the corn sample,and the sugarcane mosaic virus was invaded alone.Dye samples,and two virus complex infections resulted in samples of maize lethal necrosis disease(MLND).The corn sample source from Yuanmou was preserved by inoculation of corn by friction.During the investigation,it was found that the lethal necrosis of corn is related to altitude,that is,with the elevation of altitude,the symptoms of MLND are alleviated,and the changes in guessing symptoms may be affected by temperature.To reveal this phenomenon,artificial simulations set different temperatures and grow at different temperatures after inoculation with the virus.The specific research contents are as follows:1.The plants infected by maize chlorotic mottle virus and sugarcane mosaic virus were identified by ELISA and RT-PCR,and their complete basal sequences were determined.Biological experiments have shown that both strains from Yuanmou can be transmitted by mechanical friction.2.Corn plants cultured to the 3-leaf stage were selected from the upper two leaves and inoculated with MCMV and then transferred to 23 ℃,27 ℃,31 ℃and 35 ℃conditions.The results showed that low temperature is more conducive to the onset,the symptoms are mosaic and chlorotic mottle,and high temperature is not conducive to the onset.The incidence rate is only 6%at 35 ℃,the symptoms disappear after 14 days of inoculation,but the inoculation rate is 100%after 7 days of inoculation.After 21 days of inoculation,the relative expression of cp gene of MCMV was detected by qRT-PCR.After ultrathin sectioning,the ultrastructural changes of cells were observed by transmission electron microscopy.Quantitative analysis showed that the expression level of cp gene was down-regulated with increasing temperature.Ultrathin sections showed changes in cell ultrastructure at four different temperatures,particularly mitochondria and chloroplasts.The results of temperature conversion experiments showed that the change of symptoms was the most obvious by the conversion of the highest temperature and the lowest temperature.The results of qRT-PCR showed that the amount of virus was directly related to the expression of symptoms.The ultrastructural changes of cells with high temperature conversion to low temperature were the most obvious,and the chloroplast collapsed,collapsed and destroyed most seriously.3.The maize plants inoculated with SCMV+MCMV were cultured at four different temperatures,and the inoculation rate was detected by ELISA.The MCMV inoculation rate was 100%at four temperatures on the 14th day after inoculation,and the SCMV was at four temperatures(23 ℃).The inoculation rates at 27 ℃,31 ℃,and 35 ℃were 33%,72%,88%,and 78%.Temperature has a great influence on the SCMV vaccination rate and incubation period.On the 21st day,the combined infection of maize plants increased with the increase of temperature,and the symptoms of MCMVcp and SCMVcp were up-regulated with increasing temperature.On the 28th day,the maize plants which were grown at the highest temperature of 35 ℃ without temperature exchange,the dried leaves of the corn leaves died.The corn plants that were transferred from high temperature to the lowest temperature had new leaves growing and the plants did not die.