Analysis of the transcriptome and metabolome of the atypical interaction between the fruits of Theobroma cacao (cocoa) and the pathogenic fungus Moniliophthora perniciosa, which causes the witch's broom

• Grant number: 18/21036-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Effective date (Start): August 01, 2019
• Effective date (End): July 31, 2021
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Gonçalo Amarante Guimarães Pereira
• Grantee: Antônio José Rocha
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 16/10498-4 - Investigation of strategies of adaptation to the pathogenic life style of fungi from the Moniliophthora genus at various levels of biological organizations: species, biotypes, and geographic lineages, AP.TEM

Abstract

Cacao stands out as one of the main perennial crops in agriculture, being economically relevant for supplying the raw material for the manufacture of chocolate, a product that moves billions of dollars in the world market every year. Despite its importance, cacao is drastically attacked by several diseases that diminish its productivity and reduce the quality of the cocoa almonds. Among these, the witches' broom (VDB), caused by the pernicious Moniliophthora basidiomycete, is an important limiting factor in cocoa production in the Americas and Brazil, and to this day there is no way to eradicate VDB once installed. M. perniciosa exhibits a wide range of hosts and organs that can infect, which indicates a great adaptive ability of this pathogen. In the cacao tree, it attacks branches, floral buds and fruits. Through new generation RNA sequencing technologies, we performed a comprehensive transcriptomic analysis of VDB aiming at elucidating the molecular mechanisms and proposing new ways of controlling this disease. A database called Atlas of transcriptomic witch's broom was constructed which comprises about 60 Representative RNA-seq libraries of various stages of development, growth conditions and responses to stress M. harmful fungus under conditions in vitro and in plant. However, the infection of the fruit has not yet been fully investigated, and preliminary data indicate that there is a great difference in the infective process between branches and fruits. In addition, there is also no information available on the metabolic changes occurring in fruits. Thus, this work aims to generate information about the transcriptomic and metabolic profile of the interaction T. cacao x pernicious M., to identify and characterize genes related to the mechanism of pathogen-interaction and the result compared with the interaction of the pathogen-branch. This proposal is divided into three main sections, and in the first one we will carry out an in - depth analysis of the gene expression and the metabolic profile in the sampled conditions and tissues (fruits). In the second, we will compare the infection strategy between branches and fruits, evaluating the activated or repressed metabolic pathways in each condition. In the last section, we will develop a strategy to identify sequences of possible non-coding RNAs associated with VDB, applying this strategy to the fungus M. perniciosa. In general these data present an important advance in the study of VDB and may be used in future work, both for the elucidation of the adaptive strategies of pernicious M. as a pathogen, as for the planning of new forms of control of the VDB.