Banca de QUALIFICAÇÃO: THAIS DANIELLE DUARTE SANTANA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : THAIS DANIELLE DUARTE SANTANA
DATE: 05/03/2026
TIME: 14:00
LOCAL: Auditório 4, Instituto de Ciências Médicas
TITLE:

Identification and characterization of new viruses associated with mites of the genus Tetranychus (Acari: Tetranychidae)

KEY WORDS:

mites; spider mites; Tetranychus; virome; viral diversity; RNA-seq; high-throughput sequencing; asymptomatic viruses; agricultural pests; potential biological control.

PAGES: 115
BIG AREA: Ciências Biológicas
AREA: Genética
SUMMARY:

Resumo em inglês: Herbivorous arthropods, such as mites and insects, harbor microorganisms that play central roles in shaping their ecology, adaptation, and evolutionary diversification. Although persistent viruses in insects have been widely described, the virome of mites of the genus Tetranychus, important agricultural pests, remains poorly explored. This study aimed to characterize the repertoire of persistent viruses associated with three agronomically relevant species (T. truncatus, T. ogmophallos, and T. urticae), using high-throughput sequencing data integrated with in silico bioinformatic analyses.In Chapter 1, in T. truncatus, three positive-sense single-stranded RNA viruses related to picornaviruses were identified in comparatively analyzed transcriptomes from asymptomatic individuals. T. truncatus-associated iflavirus 1 (TtAIV-1) exhibits features consistent with a novel species within the genus Iflavirus. T. truncatus-associated virus 1 (TtAV-1) and TtAV-2 possess bicistronic genomes containing two IRES elements, suggesting the existence of yet-unclassified viral lineages. The relative abundance of these viruses varied among natural populations and experimental treatments, indicating context-dependent ecological dynamics.In Chapter 2, in T. ogmophallos, three RNA viruses were identified following viral enrichment and sequencing, including one iflavirus and two nodaviruses. T. ogmophallos iflavirus 1 (ToIV-1) formed a phylogenetically distinct lineage within the group, whereas T. ogmophallos nodavirus 1 (ToNV-1) and ToNV-2 displayed both genomic segments (RNA1 and RNA2), with conserved ratios between them. The abundance of ToIV-1 was approximately 37-fold higher than that of ToNV-2, suggesting marked differences in replicative dynamics and possibly in competitive interactions among coexisting viruses. Detection of these viruses in asymptomatic individuals raises hypotheses regarding potentially stable and ecologically relevant host–virus relationships.In Chapter 3, in T. urticae, four segments corresponding to a highly divergent novel alphanudivirus were detected through in-depth transcriptomic analyses. The transcriptional profile revealed variation in activity among viral segments and genes, as well as the presence of arthropod gene homologs interspersed with typical nudivirus genes and additional unique genes. These findings suggest latent or low-prevalence infections and support the hypothesis that different species within the genus Tetranychus harbor species-specific viral assemblages.Taken together, the results substantially expand current knowledge of viral diversity associated with Tetranychus, highlighting the complexity and specificity of viromes in phytophagous mites. These data provide conceptual and molecular foundations for future investigations into virus–host interactions and their potential impact on sustainable agricultural pest management, including possible biotechnological applications.

COMMITTEE MEMBERS:
Externo à Instituição - ERICH YUKIO TEMPEL NAKASU - EMBRAPA
Externo à Instituição - MIGUEL DE SOUZA ANDRADE - EMBRAPA
Presidente - 2594909 - SEBASTIEN OLIVIER CHARNEAU
Externa ao Programa - 1775446 - TATIANA AMABILE DE CAMPOS - null