Physiological And Biochemical Index Changes And Transcriptomic Analysis Of Sugar Beet Brown Spot Resistant And Susceptible Materials

Sugar Beet(Beta vulgaris)is an important sugar crop and the main source of sucrose in many countries,with important economic value.Cercospora leaf spot is a fungal disease caused by cercospora beticola Sacc.,which has severely affected the planting and production of sugar beets.This illustrates the importance of sugar beet resistance breeding.In order to provide a better theoretical basis for sugar beet resistance breeding,this study carried out plant pathology research,plant defense enzyme research and transcriptome analysis.In this study,we observed the morphological structure and ultrastructure of beet leaves infected with C.beticola,analyzed some of the pathological characteristics of Cercospora leaf spot,and at the same time studied the genetic changes of sugar beet leaves after inoculation with C.beticola.The differentially expressed genes related to disease resistance were screened out,which provided abundant gene resources for further cloning and functional verification of genes related to Cercospora leaf spot resistance.The main conclusions of this study were as follows:(1)The physiological changes of the susceptible material KWS9147 in sugar beet were obvious during the infection process.The stomata in beet leaves were destroyed on the 8th day of infection.When the fungus infected beet cells,it would destroy the organelle first,and then destroy the whole cell.After infection,beet leaves will appear small spots on the 5th day,patches on the 10 th day,and large areas of necrosis on the15 th day.(2)Sugar beet related changes in the biochemical indicators include: in the process of infection,disease-resistant varieties of PPO,POD and SOD activity will increase,the average of the three kinds of enzymes in resistant varieties activity were higher than that of susceptible varieties,showed that resistance to Cercospora leaf spot associated with the 3 kinds of enzyme activity,PAL activity and frequently change is bigger,and sugar beet resistance correlation is relatively low.The average activity of PG and Cx in resistant cultivars was also higher than that in susceptible cultivars,which indirectly indicated that resistance of resistant cultivars was stronger than that of susceptible cultivars.The activities of PG and PPO increased significantly in a short time after infection,indicating that these enzymes belonged to the early acting enzymes.The activities of Cx,POD and SOD increased obviously after a period of infection,which indicated that these enzymes belonged to the late acting enzymes.(3)High-throughput transcriptome sequencing This study completed transcriptome analysis of 6 samples,obtained 47.67 Gb Clean Data,and detected 25822 expressed genes,42610 expressed transcripts,and differentially expressed genes.There were 5714 genes,of which 2583 genes were up-regulated and 3131 genes were down-regulated.Through GO functional significance enrichment analysis and KEGG metabolic pathway analysis,it was found that plant hormone signal transduction,phenylpropanol biosynthesis,plant-pathogen interaction,glutathione metabolism and other genes were significantly up-regulated,which indicated that these genes had a high correlation with the resistance to Cercospora leaf spot,and the resistance of these genes could be further explored.