Reinoculation and two-dimensional electrophoresis were performed to analyze the pathogenicity differentiation of Curvularia lunata.Resistant host inbred lines Shen135,Mo17,and 78599-1 were reinoculated(six generations) with low virulent isolate WS18.Results showed that the disease index had no significant change for the first 2 generations of inoculation.At the third generation,the incidence of disease was increased and the number of differential expressed proteins of mycelia were more than that in the first 2 generations.More than 100 differential expressed proteins were found in the mycelia of fifth generation when compared with the original one.In the experiment,10 differentially expressed proteins were identified by MALDI-TOF-MS analysis.Three proteins were related directly to the differentiation of virulence,2 were related to allergen,4 were related to the metabolism of carbon or signaling pathway and 1 was unkonwn to Curvularia lunata.
It was found that activities of cellulase and pectolytic enzyme produced from Curvularia lunata,were significantly affected when the pathogen inoculated on various maize germplasms with different resistant levels.Isolate 98-07,which inoculated on resistant germplasms for single generation,was induced relatively higher average cellulase activity(7.99 U/mL) than that induced on susceptible germplasms(4.91 U/mL).By consecutively inoculating low pathogenicity isolates C107 and WS18 on resistant inbred line Shen135 for 5 generations,we found that their pathogenicity improved generally as the increase of generations,and simultaneously their cellulase activities were also enhanced(C107∶32.0%;WS18∶72.2%).The data indicated that there is a significant correlation between isolate cellulase activities and the changes of its pathogenicity(C107∶r=0.916;WS18∶r=0.905) induced specifically on resistant germplasms.
