Comparative analysis reveals changes in transcriptomes of sugarcane upon infection by Leifsoniaxyli subsp. xyli

Authors: FU, YUHUA - Guizhou Academy Of Agricultural Sciences; WEI, JIN-JU - Guangxi Academy Of Agricultural Sciences; Pan, Yong-Bao; ZHOU, XIANG - Collaborator; HE, ER-QI - Guizhou Academy Of Agricultural Sciences; LIU, RONG - Guizhou Academy Of Agricultural Sciences; HUANG, HUI - Collaborator; LU, JIA-JU - Guizhou Academy Of Agricultural Sciences; LIU, FAN-ZHI - Guizhou Academy Of Agricultural Sciences

Submitted to: Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2019
Publication Date: 9/24/2019
Citation: Fu, Y.-H., Wei, J.-J., Pan, Y.-B., Zhou, X., He, E.-Q., Liu, R., Huang, H., Lu, J.-J., Liu, F.-Z. 2019. Comparative analysis reveals changes in transcriptomes of sugarcane upon infection by Leifsoniaxyli subsp. xyli. Journal of Phytopathology. 167:633-644. https://doi.org/10.1111/jph.12856.
DOI: https://doi.org/10.1111/jph.12856

Interpretive Summary: The Leifsonia xyli subsp. xyli (Lxx) bacteria cause sugarcane ratoon stunting disease (RSD) that if not controled, can greatly reduce the cane yield and juice quality. The most effective method to control the disease is to breed RSD-resistant varieties. However, improvement of sugarcane for RSD resistance is hindered by limited information on the molecular mechanisms underlying Lxx infection and defense responses in sugarcane. In this study, a RSD-resistant variety CP72-2086 and a RSD-susceptible variety GT11 were involved. Plants of the two varieties were inoculated with Lxx bacteria. At five different time points post infection, gene expression (poly-A mRNA) samples were collected for cDNA library contrcution and DNA sequencing in order to identify the candidate genes involved in RSD resistance. Each treatment was repeated five times. In total, 14,494 differentially expressed genes (DEGs) were identified as the result of Lxx infection. Enrichment analysis showed that genes related to the hormone signal transduction, phenylalanine metabolism, phenylpropanoid biosynthesis, and starch and sucrose metabolism were responsible for sugarcane response to Lxx-infection. Plant hormone signaling pathway genes were significantly differentially expressed at the early infection stage between the two varieties. CP72-2086 resisted Lxx infection through jasmonic acid- and ethylene-dependent host-defense pathways, whereas GT11 preferred the salicyclic acid-dependent host-defense pathways. The findings may help unravel the molecular mechanisms of sugarcane-Lxx interaction and may pave the way for sugarcane breeding for disease resistance.

Technical Abstract: Ratoon stunting disease (RSD) caused by bacterium Leifsonia xyli subsp. xyli (Lxx), is a devastating disease of sugarcane over a large part of the world. Genetic improvement for RSD-resistant varieties is considered the most effective method to control the disease. However, genetic improvement of sugarcane is hindered by the limited information about the molecular mechanisms underlying Lxx pathogenicity and defense responses in sugarcane. In this study, genome-wide gene expression profiling was used to compare RSD resistant (CP72-2086) and RSD susceptible (GT11) genotypes at different infection stages in order to identify the candidate regulators for RSD resistance. A total of 14,494 differentially expressed genes (DEGs) were identified, indicating that dramatic changes had occurred in gene expression upon Lxx infection, especially in the susceptible genotype. Enrichment analysis showed that a large number of genes related to plant hormone signal transduction, phenylalanine metabolism, phenylpropanoid biosynthesis, and starch and sucrose metabolism were responsible for sugarcane response to Lxx-infection. Plant hormone signaling pathway genes were significantly differentially expressed at the early infection stage between the two genotypes with the smallest false discovery rate values. The resistant genotype chose the JA- and ET-dependent host-defense pathways to resist Lxx infection, whereas the susceptible genotype preferred the SA-dependent host-defense pathways. These findings help unravel the molecular mechanisms of sugarcane plant-Lxx interactions and may pave the way for sugarcane breeding for disease resistance.