Análise da interação entre guaranazeiro (Paullinia cupana var. sorbilis) e Fusarium decemcellulare agente causal do superbrotamento: uma visão morfoanatômica, transcriptômica e proteômica

Abstract

Oversprouting is a disease caused by the fungus Fusarium decemcellulare that affects the guaraná tree (Paullinia Cupana var. sorbilis), a native Amazonian species, widely used by the soft drinks, cosmetics and pharmaceutical industries. Among the diseases that have an economic impact on guarana is oversprouting that affects plant growth and development, which is characterized by three different symptoms depending on the affected tissue: 1- stem galls, 2- oversprouting of vegetative buds and 3- oversprouting of inflorescences, these symptoms compromise productivity and can cause losses of up to 100%. In order to identify and characterize anatomical, histological and molecular alterations, comparative analyzes in symptomatic and asymptomatic tissues were carried out based on different approaches such as: light and electron microscopy, genomic, transcriptomic and proteomics. The morphoanatomical analyzes reveal that the different symptoms present a marked reduction in the longitudinal axis and the formation of “capsules”, with thick and hard outer walls. When the infection affects the inflorescences, extremely malformed floral organs with multiple flowers within a single flower are also observed, and in the vegetative buds the vegetative primordia are poorly differentiated, with the formation of multiple malformed organs and an axillary meristem encapsulated by very thickened bracts. On the other hand, the aggregation of multiple capsules in the same branching point produces the symptom called gall. The morphological aspects observed in the symptoms suggest a possible hormonal imbalance, which was corroborated by the identification in the complete genome of the pathogen of genes for auxin production pathways (AIA) in F. decemcellulare and subsequent metabolomic analysis that confirmed the production. These first indications, together with the data of differentially expressed genes in the transcriptome comparing symptomatic and asymptomatic tissues of the three different symptoms of the disease, provided the first indications of the molecular mechanisms of action of the pathogen and the consequences of hormonal imbalance are presented in chapter I of this thesis. For a better understanding of the mechanisms that trigger the disease in guarana, the interaction proteome was also obtained, where 3404 guarana proteins were identified, of which 253 were differentially abundant between diseased and healthy tissue. These results confirm the transcriptomic observations and reinforce the role of the imbalance caused by auxin in oversprouting. All proteins of the SCF mechanism (Skp1–Cullin–F-box) of auxin response were identified and the differential abundance of some SCF components and proteins related to AIA conjugation in diseased tissue reinforce the role of imbalance in infected tissue. Difference in the abundance of proteins such as IAR3, IAGLU and AGO10 that allow greater ability in irreversible conjugation (AIA-Asp and AIA-Glu) and Argo10 related to "downstream" modulation of the auxin response with consequent restoration of hormonal balance are more effective in genotypes with higher level of resistance.