Association analysis of leaf structure and defense enzyme activity with fire blight resistance in different pear germplasms
In order to clarify the relationship between pear fire blight and leaf structure and defense enzyme activity,the anti fire disease resistant Pyrus betulifolia Bunge.selected by the research group in the early stage was taken as the research object,and ordinary Pyrus betulifolia Bunge.,'Korla fragrant pear'and Pyrus ussuriensis Maxim.were used as controls,and evaluated the resistance of four pear germplasms by the method of incised inoculation,observing and measuring the wax content of the leaves,the stomatal characteristics,the transverse structure of the leaves as well as the six defense enzyme activity indexes,and using analysis of variance(ANOVA)and correlation studies to study the relationship of leaf structure and defense enzyme activity with the resistance to pear fire blight.The results showed that the resistance of four pear germplasms to fire blight was as follows:resistant Pyrus betulifolia Bunge.(MR)≈Pyrus ussuriensis Maxim.(MR)>ordinary Pyrus betulifolia Bunge.(S)≈'Korla fragrant pear'(S).There was no significant correlation between leaf wax content and disease index.The correlation coefficients between stomatal density,leaf thickness,upper epidermal thickness,and lower epidermal thickness and disease index were 0.959,0.951,0.978,and 0.991,respectively,all showing significant or extremely significant positive correlation.After inoculation with Erwinia amylovora,the activities of SOD,CAT,PPO,and PAL in the leaves were effectively increased,and the resistant germplasm was higher than the disease-susceptible germplasm.The MDA content of the disease-resistant germplasm decreased the most(the resistant Pyrus betulifolia Bunge.and Pyrus ussuriensis Maxim.decreased by 48.33%and 38.42%,respectively).Therefore,the lower epidermal thickness of pear leaves can be a preliminary indicator of fire blight resistance,while the stomatal density,the thickness of the leaves,and upper epidermal thickness can be used as an auxiliary reference index;the changes in SOD,CAT,PPO,PAL activity and MDA content were most obvious,and the peak activity of the six defense enzymes can be used as a preliminary physiological indicator for early identification of pear resistance to fire blight.This study can provide new ideas and lay a theoretical foundation for the selection of disease-resistant pear germplasm resources.
万方数据
维普
