Uncovering the roles of small RNA pathways during Moniliophthora perniciosa x host interaction using tomato (cv. Micro-tom) as a proxy: integrating functional and genomic approach

• Grant number: 20/16411-3
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date until: November 15, 2021
• End date until: November 14, 2022
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Antonio Vargas de Oliveira Figueira
• Grantee: Eder Marques da Silva
• Supervisor: Tamas Dalmay
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: University of East Anglia (UEA), England
• Associated to the scholarship: 17/17000-4 - Analysis of the interaction Moniliophthora perniciosa x 'Micro-Tom' tomato: non-host type resistance, effects on the development and role of phytohormones in pathogenesis, BP.PD

Abstract

Moniliophthora perniciosa is the causal agent of witches' broom disease (WBD) in Theobroma cacao, the 'chocolate' tree. This pathogen is considered a threat to world cacao production. The M. perniciosa x host interaction is difficult to investigate as such interaction occurs between two non-model organisms. To circumvent such limitations, tomato can be used as a model due to its susceptibility to isolates of the S-biotype of M. perniciosa. Similar to cacao, the infection of Micro-Tom (MT) led to stem swelling and axillary shoot outgrowth, producing broom-like symptom. Although some advances were made toward the understanding of this pathosystem, several aspects remain elusive. In this context, the participation of small non-coding small RNA (sRNA) (e.g. microRNAs and siRNAs) pathways have not been explored. In this proposal, we have two important goals. Firstly, we want to determine the role of the microRNA156/SBP box pathway during M. perniciosa x host interaction. To do so, we will integrate our previous data (acquired via a functional approach) with a high resolution mRNAseq. In our previous results, we showed that transgenic plants (cv. MT) overexpressing the AtMIR156 (OEMIR156) is highly susceptible to M. perniciosa infection. Thus, we will perform a comparative mRNAseq from symptomatic stem between tomato (cv. MT) and the highly susceptible transgenic plants overexpressing the AtMIR156 (OEMIR156) at 40 days after inoculation (DAI) and non-inoculated plants. Together with our functional results, this mRNAseq approach will provide an overview of the molecular mechanism of the infection process. Such analysis will be the key to understand why OEMIR156 is highly susceptible to the pathogen, since we have shown that this is the only tomato genotype (to our knowledge) where the pathogen is capable to evolve to the necrotrophic phase (starting at 40 DAI). We expect to link for the first time, the interaction between M. perniciosa x host with a specific sRNA pathway. Our second goal is also based in our previous results. We made a microRNA transcriptomic profile from MT. We found several plants' microRNAs differentially expressed in response to infection. Besides, in such library, we have previously found at least 33 sRNAs from the M. perniciosa during the interaction. Thus, we will perform a degradome library from MT stem tissue at 30 DAI comparing to non-inoculated plants, which will allow us to evaluate globally the sRNA targeted mRNAs during the interaction. We will compare the degradome results with our microRNA transcriptomic profile from MT inoculated plants to verify the detailed impact of M. perniciosa infection on sRNA profile tomato. We will evaluate, via the degradome analyses, whether some of these sRNAs are potentially acting as a virulence factor by targeting host mRNAs. We will also investigate whether host sRNAs target fungal mRNAs. Finally, we intend to investigate the sRNA transcriptomic profile from roots of MT at 30 DAI. We have previously shown that M. perniciosa disrupt the MT root development and sRNAs are required to proper root development. (AU)