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The pathogenic mechanism analysis of sugarcane ratoon stunting disease base on histology and transcriptomics

Ying Guo: Fujian Institute of Subtropical Botany

<div>Sugarcane ratoon stunting disease (RSD) is worldwide. In this research, we inoculated Lxx to Badila to explore the infecting process, obtained differential gene expression profile of sugarcane interacting with Lxx, and identified genes which were expressed differentially and confirmed involving in key metabolic pathways and signal transduction by q-PCR. Detailed results were as follow.</p> <p>1 Results of in-situ PCR of stem and leaf from infected Badila showed Lxx maily distributed in xylem and phloem in stem, xylem in main vains and bundle sheath cells near upper epidermis, vascular bundle sheath cell wall in mesophyll tissue and the mesophyll cells. Pathological section observed in microscope displayed that cell wall of "wreath" mesophyll cells outside leaf bundle sheath was thin and shrinked irregularly, and sugarcane stem cells of vascular bundles in the xylem and phloem cells were hashed obviously. Lxx quantitative analysis results in infected sugarcane stem showed that the extent of damage in phloem and xylem of vascular tissue and Lxx bacteria planting density were positively correlated;</p> <p>2 The differential transcriptome analysis among various stages in infected sugarcanes showed that the differential expressed genes mainly involved in plant hormone signal transduction, phenylalanine metabolism, phenylpropanoids biosynthesis, carbon metabolism, photosynthesis, plants and pathogen interactions. SA activated PR gene expression and induced sugarcane to produce system acquired resistance. Phenylalanine metabolic pathway was also activated responsing to Lxx stress, and defense system was started. The key genes involved in photosynthetic organism carbon fixation were down-regulated, maybe Lxx destroyed photosynthesis is one of the reason for leading to stunting disase in sugarcane.</div>