Dichorhavirus coffeae: distribuição Geográfica, caracterização genética e estudo da interação com a hospedeira chenopodium quinoa willd

Abstract

Coffee is the most traded agricultural commodity in the world, and Brazil is the largest producer and exporter. Within Brazil, the state of Minas Gerais holds the largest share of production. Among the factors that can decline production and final quality of the grain is Dichorhavirus coffeae (CoRSV), the etiological agent of coffee ring spot virus. CoRSV is widely disseminated in Coffea arabica plantations in Brazil. Monitoring the genetic diversity of isolates in the field is essential to verify the occurrence of mutation and recombination events, factors that can completely alter the dynamics of the plant-virus-vector interaction. Chenopodium quinoa plants have been used as an indicator for CoRSV; however, when inoculated and kept at high temperatures (between 28 and 35 °C), unlike what occurs in C. arabica plants, in which the symptom is only local, the virus presents infection and systemic symptoms. Several reports indicate that biotic and abiotic factors, such as the presence of the virus and increased temperature, can alter the dynamics of reactive oxygen species and antioxidant enzymes. The aim of this study was to detect CoRSV in 21 municipalities in Minas Gerais, investigate genetic diversity and phylogeographic clustering based on partial and complete nucleocapsid protein. Combine incidence information and generate a map of CoRSV distribution in Brazil. Demonstrate virus detection in C. quinoa plants with different symptomatological conditions, as well as investigate the dynamics of reactive oxygen species, antioxidant enzymes (SOD, APX and CAT) and MDA levels in C. quinoa plants when inoculated with CoRSV and kept at high temperature. All municipalities tested positive for the presence of the virus. Compiling data from the literature, it was possible to verify the distribution of CoRSV in seven Brazilian states and 45 municipalities. For the 16 sequenced isolates, the complete nucleocapsid protein follows the pattern of the partial one, demonstrating that there is phylogenetic grouping based on the region. However, they follow a tendency of grouping by mesoregion. No recombination events were found and codons presented diversification and purification mutation, with the vast majority under neutral selection. The detection of CoRSV by RT-PCR in C. quinoa is dependent on symptomatic material, even in plants with systemic infection. When C. quinoa plants were inoculated with CoRSV and kept at high temperature, there was greater lipid peroxidation, quantified by malondialdehyde (MDA) levels. Under these conditions, the plant cannot efficiently eliminate the superoxide anion, even with high SOD activity and, combined with virus damage, causing high peroxidation. The plants presented lower levels of H2O2, APX and CAT. In conclusion, it is possible to verify that there may be transfer of contaminated material between mesoregions, which may be a form of inspection by competent agencies. To perform the detection of CoRSV in C. quinoa, symptomatic material must be selected. This was the first study investigating the interaction of CoRSV and C. quinoa at the crucial moment forsystemic infection, demonstrating the increase in MDA level