Transcriptome profiles of a native rice variety Hongyou-4 responding to infections of hypervirulent and hypovirulent Xanthomonas oryzae pv. oryzicola strains

Abstract

Bacterial leaf streak of rice (BLS), caused by Xanthomonas oryzae pv. oryzicola (Xoc), is an increasingly serious disease in southwestern China. This study aimed to evaluate the response of the native rice variety Hongyou-4 (HY4) to two different transcription activator-like effectors (TALEs) genotypes of Xoc. HY4 was significantly susceptible to Xoc strain 13T19 and resistant to Xoc strain YM15. Transcriptomic analysis of HY4 leaves inoculated with the two Xoc TALEs genotypes revealed 1339 and 1219 differentially expressed genes (DEGs) in rice inoculated with Xoc strain 13T19 (HY.Q) and Xoc strain YM15 (HY.R), respectively, compared to the control. Quantitative real-time PCR (qRT-PCR) for expression of 10 randomly selected genes was used to verify the RNA-Seq data. Gene ontology (GO) analysis of the transcriptomic data showed DEGs of defense-related genes were predominantly assigned to 11 GO terms, with nine terms showing differential expression in HY4 after inoculation with the two Xoc genotypes. KEGG pathway clustering analysis revealed DEGs involved in plant-pathogen interactions and secondary metabolite pathways of phenylpropanoid biosynthesis were down-regulated in HY.Q compared to HY.R. Four transcription factors including bZIP, GLK, MADS, and MYB families, three resistance genes, and the TalAM2 effector target gene OsSWEET13, were differentially expressed in HY4 inoculated with the two Xoc TALEs genotypes. These data clarify the mechanism of interactions between rice and different TALE genotypes of Xoc, and can help reveal disease-related metabolic pathways, molecular regulatory networks, and candidate genes involved in rice responses to TALEs of Xoc.