| Canker disease and Cytospora chrysosperma disease are the most serious diseases of poplar. Two kinds of diseases are closely related to the water physiology of poplar. Although the use of pesticides and biological control methods have achieved great results, but from another point of view, breeding disease resistant varieties is the most effective means. In view of the disadvantages of conventional breeding, it becomes more and more urgent to understand the mechanism of plant disease resistance through genetic engineering. The research to the most easily infected Beijing Yang as the experimental material, through high-throughput sequencing, of ulcer disease and rotten skin disease stress Populus Beijingensis miRNA difference expression and changes of water physiology of poplar after two kinds of diseases, in order to breeding for disease resistance to provide more information. The results obtained are as follows:1 In the fourth day after treatment, the loss rate of water conductance was significantly higher than that of the canker group? Cytospora chrysosperma disease group compared with the control group. Sixth, eighth days of the two group and the control group between the water loss rate of the difference was not significant. Two kinds of bacteria treatment plants under water by variation of loss rate agreement. Therefore, two kinds of bacteria treatment of the experimental results table, two kinds of bacteria in the initial stage significantly reduced the water dredging capacity of poplar, and with the extension of the experimental treatment time, Beijing poplar water transport capacity gradually restored.2 The top water potential of the plant was sixth and eighth days after the treatment, and the treatment group was significantly lower than that in the control group at and two days after the treatment. Fourth days after treatment, the difference between the top water potential of the two groups of canker and Cytospora chrysosperma disease and the control group was not significant. And the top water potential was gradually decreased after treatment. Populus Beijingensis inoculation upper branches of water to lead the loss rate in pathogens at the beginning of the treatment significantly reduced the plant's water dredge ability, with the extension of treatment time, moisture content translocation ability is restored gradually. The change of the top water potential and the change of the water conductance loss rate of the xylem is the synchronization. With the decrease of water potential, the loss rate of water conductance was increased. All of these further proved that the canker and Cytospora chrysosperma disease are water related diseases.3 Determination of soluble sugar and starch content in phloem and xylem in canker ?Cytospora chrysosperma disease treated and the control group plants were inoculated with upper branch and lower branch. The results showed that the contents of soluble sugar in the stem of poplar were increased fourth, sixth and eighth days after treatment, and the soluble sugar content in the stem of the poplar branch was increased in the two groups. However, the effect of pathogen treatment on the soluble sugar content of stem xylem was not significant. The content of soluble sugar in the phloem and xylem of the upper part of inoculation was higher than that in the lower part. The soluble sugar showed a vertical distribution in the phloem and xylem. Experimental treatment after the 4, 6, 8 days, pathogen treatment of two groups and the control group of branch phloem xylem and the Ministry of starch content had no obvious regularity, pathogen treatment effect on shoot starch content was not significant.4 Using Illumina high-throughput sequencing technology,the small RNA of the sample under the stress of canker? Cytospora chrysosperma disease were sequenced. Detected 54090831 clean reads of known miRNA and 30155744 clean reads of the new mi RNA. Target gene prediction of differentially expressed genes, these predicted target genes have a variety of functions. It is found that the target gene of miRNA482c-3p? novel-401?novel-439 is the disease course protein. Target genes of miRNA172, miRNA 169, miRNA 166 and many other family genes were correlated with resistance to stress. Most of the predicted target genes are related to the physiological metabolism of the plant.GO function analysis of target genes of differentially expressed genes.Many target genes are associated with transcription, metabolism, and stress related proteins. These proteins may play an important role in the regulation of gene network when confronted with the stress of disease. Pathway enrichment analysis of KEGG, gene expression of these significant differences were analyzed. 2 pathways were found to be related to plant disease resistance. This is of great value to our follow-up study. To further reveal the pathological mechanism and water physiology of poplar canker?Cytospora chrysosperma disease. |
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