Selecting And Proteomic Analysis Of Magnaporthe Oryzae Under Extreme Low-temperature

Rice is the main crop in northeastern region of China, and as one of three majordiseases of rice, rice blast has brought great threat to rice production. In recent years,rice blast has become the most important serious diseases in northeastern of China. Itis extremely difficult to be prevented and controlled because of its frequent variation.Compare epidemic characteristics of rice blast between the northeastern and southernareas, we found that extreme low-temperature was the most important differencebetween these two regions, and we speculated that extreme low-temperature promotedthe variation of the rice blast fungus Magnaporthe oryzae. We performed that thetolerance comparisons to low temperature between different strains of M. oryzaeisolated from rice fields of northeastern and southern China and tried to find themechanism. This study provided important information for exploring the effect ofenvironmental factors on M. oryzae, and effective strategy for preventing andcontrolling rice blast.We confirmed-15℃as the extreme low-temperature condition. Statisticalanalysis indicated that there were individual differences in low temperature tolerancebetween different strains.57.9%of northeastern strains could survive after treated-15℃more than three weeks whereas4.7%of them died in one week.Approximately56.2%of southern strains died after treated-15℃two weekswhereas4.5%of them could tolerate low temperature of-15℃more than threeweeks. Obvious geographical differences were observed between northeastern andsouthern isolates.34.8%strains from northeastern china could not tolerate-15℃one week, however there were only4.7%southern strains died.95.5%southernstrains died after three weeks of-15℃, however57.9%trains from northeasternchina still could survive. The strains from northeastern and southern china were divided into four groupsaccording to difference in low temperature tolerance. Average relative conductivityanalysis showed that the strains which had the stronger low-temperature toleranceown the lower relative conductivity.Ten strains were selected and subjected to the critical lethal low temperature forsuccessive generations, the results indicated that eight strains were improved on low-temperature tolerability after fifty-five cycles of repeated freeze-thaw treatment.Resistance to tricyclazole of some strains changed, but this was not universal. Thethermal hysteresis activity of isolate200805apoplast protein increased after repeatedfreeze-thaw treatment.Two-dimensional electrophoresis system and technology of M. oryzae weresuccessfully established. Apoplast protein spectra of isolate200805changed afterrepeated freeze-thaw treatment. Two-dimensional electrophoresis showed more thantwo hundreds protein spots,38spots up-regulated and18spots down-regulated.