Omics' application for the study of two fungal cocoa diseases

Author(s)

Alinne Batista Ambrosio

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2012-02-08

Examining board members

Gonçalo Amarante Guimarães Pereira; Aristóteles Goes Neto; Lazaro Eustáquio Pereira Peres; Carlos Augusto Colombo; Renato Vicentini

• Advisor: Odalys García Cabrera; Gonçalo Amarante Guimarães Pereira

Abstract

Cacao tree (Theobroma cacao L., Sterculeaceae) is a native plant from Amazon region andthe main species commercially exploited for seed production among the 22 of the genus.This plant has a great economic importance because of its use in the production ofchocolate. Due to this, producing regions always has been concern to seed production,and diseases are the most important factors of decline in cocoa production. In Brazil,cacao witches' broom and ceratocystis wilt are major diseases causing production losses.The witches' broom is caused by the fungus Moniliophthora perniciosa and thecharacteristic hyperplasia and hypertrophy symptoms of cells gives rise to anomaloustissue called broom. Meanwhile, the ceratocystis wilt caused by Ceratocystis cacaofunestais an asymptomatic disease; it is detected only with the death of the plant. Both diseaseswere studied using genomic tools in an attempt to identify mechanisms of host-pathogeninteraction. In Ceratocystis cacaofunesta, a mitochondrial global analysis integrating datafrom genomics, transcriptomics and proteomics was made. This work generated the firstinventory of mitochondrial proteins of a plant pathogenic fungus, in which 1,124 proteinswere predicted and 304 were identified experimentally. Among the proteins listed in theinventory, 117 have unknown function and 7 appear to be specific to this fungus. Dataanalysis of the genome of M. perniciosa suggests that the fungus could be producinggibberellin, it may explain much of the events that happen during the interaction M.perniciosa-cacao in biotrophic phase of the fungus. Therefore, this work showed theimportance of this hormone in disease progression, as well as altered metabolism ofgibberellin in the plant during the interaction. The data obtained in this work generatedknowledge to develop strategies to control these two diseases, and can drive studies withother pathogens (AU)