Gene Expression Profile of Mexican Lime (Citrus aurantifolia) Trees in Response to Huanglongbing Disease caused by Candidatus Liberibacter asiaticus.

Nowadays, Huanglongbing (HLB) disease, associated with Candidatus Liberibacter asiaticus (CLas), seriously affects citriculture worldwide, and no cure is currently available. Transcriptomic analysis of host-pathogen interaction is the first step to understand the molecular landscape of a disease. Previous works have reported the transcriptome profiling in response to HLB in different susceptible citrus species; however, similar studies in tolerant citrus species, including Mexican lime, are limited. In this work, we have obtained an RNA-seq-based differential expression profile of Mexican lime plants challenged against CLas infection, at both asymptomatic and symptomatic stages. Typical HLB-responsive differentially expressed genes (DEGs) are involved in photosynthesis, secondary metabolism, and phytohormone homeostasis. Enrichment of DEGs associated with biotic response showed that genes related to cell wall, secondary metabolism, transcription factors, signaling, and redox reactions could play a role in the tolerance of Mexican lime against CLas infection. Interestingly, despite some concordance observed between transcriptional responses of different tolerant citrus species, a subset of DEGs appeared to be species-specific. Our data highlights the importance of studying the host response during HLB disease using as model tolerant citrus species, in order to design new and opportune diagnostic and management methods.

De novo assembly and functional annotation of Citrus aurantifolia transcriptome from Candidatus Liberibacter asiaticus infected and non-infected trees.

Mexican lime (Citrus aurantifolia) belongs to the Rutaceae family and nowadays is one of the major commercial citrus crops in different countries. In Mexico, Mexican lime production is impaired by Huanglongbing (HLB) disease associated to Candidatus Liberibacter asiaticus (CLas) bacteria. To date, transcriptomic studies of CLas-Citrus interaction, have been performed mainly in sweet citrus models at symptomatic (early) stage where pleiotropic responses could mask important, pathogen-driven host modulation as well as, host antibacterial responses. Additionally, well-assembled reference transcriptomes for acid limes including C. aurantifolia are not available. The development of improved transcriptomic resources for CLas-citrus pathosystem, including both asymptomatic (early) and symptomatic (late) stages, could accelerate the understanding of the disease. Here, we provide the first transcriptomic analysis from healthy and HLB-infected C. aurantifolia leaves at both asymptomatic and symptomatic stages, using a RNA-seq approach in the Illumina NexSeq500 platform. The construction of the assembled transcriptome was conducted using the predesigned workflow Transflow and a total of 41,522 tentative transcripts (TTs) obtained. These C. aurantifolia TTs were functionally annotated using TAIR10 and UniProtKB databases. All raw reads were deposited in the NCBI SRA with accession numbers SRR10353556, SRR10353558, SRR10353560 and SRR10353562. Overall, this dataset adds new transcriptomic valuable tools for future breeding programs, will allow the design of novel diagnostic molecular markers, and will be an essential tool for studying the HLB disease.