Physiological Index Analysis Of Citrus Plants Infected By Huanglongbing And Protein Expression Ofβ-ketoacyl-ACP Reductas (FabG) In Candidatus Liberibacter

Huanglongbing(HLB) is caused by the phloem coli and caused devastating losses to citrus industry. There is no effective method of prevention and cure of the disease, also do not have citrus varieties of available resistance. Citrus infected by HLB will show the yellowing condition. HLB could result in yield and quality reduction to citrus, and even to death eventually. Their were great changes at physiology and metabolism level of citrus infected by HLB. Study of these inner physiological and metabolic changes can explain to some extent of the pathogenesis of HLB.Multiple physiological indexes of the citrus leaves and phloem including soluble sugar, starch, protein and various sugar or acid were determined and analyzed in this study. The content of soluble sugar, starch and protein in healthy and infected citrus have significant difference. After infection, in citrus leaf the contect of soluble sugar, starch and protein were increased to2.92,45.83,1.81times; the content of Each index in the phloem raised to2.26,7.17,2.27times, respectively. The Meteorological chromatography used to determine the contect of malic acid, citric acid, fructose, glucose, inositol and sucrose. To analyze the content of these sugars and acids changes, show that after infection, the content of malic acid in the phloem fell to76%; there were no changes in the content of citric acid; the content of fructose in the leaves up to1.15times; the content of glucose in the leaves and phloem rose to1.11and1.03times respectively; the content of inositol rose to1.29and1.25times respectively; And more specifically, the content of sucrose in leaves was from0to28.58mg/g, in the phloem by7.27mg/g up to64.23mg/g.According to the genome sequence of HLB published on the NCBI, we have designed primers G+and G-used for PCR and cloned the target fragment of744bp. Through connect the gene fragment to pM19-T Vector and compare to the genome sequence, the consistency of result was100%. Then FabG gene fragment was connected to the PET-28a vector and transformed into E. coli. Take positive clones under the IPTG concentration of0.1mM can express FabG protein in large quantities. SDS-PAGE was carried out on the protein expressed, the result show that most FabG protein was in precipitation.