Biology subjects

Xavier, C. A. D.

Publications and source records attributed to Xavier, C. A. D..

5 recordsLinked to original sources

bioRxiv2025

Evolution of ssDNA plant viruses in the natural environment - a journey through time

Begomoviruses pose a major threat to food security, particularly in developing countries. These small ssDNA viruses exhibit substitution rates comparable to those of RNA viruses. The temporal dynamics of begomoviruses in non-agricultural environments have been largely overlooked, and little is known about how these viruses evolve in the absence of anthropogenic influence. In this study, we investigated the temporal dynamics of begomoviruses in a small fragment of regenerating Atlantic Forest area in the state of Minas Gerais, Brazil. Samples of Sida acuta, a wild plant native from South America, were collected at the same location over a 12-year period (2011-2022). Five distinct begomoviruses were detected infecting this host: OxYVV, SiYLCV, SimMV, MaYVV, and SiMV. OxYVV and SimMV were subdivided into multiple variants, revealing their potential as reservoirs of viral biodiversity. Several shifts in species and variant composition were observed in the viral community over time, with the most drastic change occurring in 2016, when SiYLCV outnumbered OxYVV. The reasons behind this turnover remain uncertain, but the most compelling clues point to a population expansion of SiYLCV. We detected a strong temporal signal in two of the most abundant viruses (OxYVV and SiYLCV), which allowed us to calibrate molecular clocks and estimate substitution rates for both of them. Our results indicate that, even in the natural environment, begomoviruses can evolve at rates similar to those reported in agricultural systems.

microbiology↗

bioRxiv2024

Ruvbl1 is required for the reproduction of the corn planthopper, Peregrinus maidis

Ruvbl1 (also known as TIP49, Pontin) encodes an ATPase of the AAA+ protein superfamily involved in several cellular functions, including chromatin remodeling, control of transcription, and cellular development (motility, growth, and proliferation). Here, we used an in-vivo RNA interference (RNAi) approach to evaluate the effect of Ruvbl1 silencing on the physiology of the corn planthopper, Peregrinus maidis. Silencing of P. maidis Ruvbl1 (PmRuvbl1) was correlated with visible morphology changes in female individuals with significant increases in body mass observed at 8 and 12 days after double strand RNA (dsRNA) injection. Ovary morphology was significantly affected in adult females with PmRuvbl1 silenced, with no mature oocytes observed at 8 and 12 days after gene silencing. Whereas no significant difference in egg laying was observed 4 days after dsRNA injection, significantly fewer eggs were laid in plants at 8 and 12 days after dsRNA treatment. Furthermore, dramatic reductions in egg hatching were observed at all time points after PmRuvbl1 silencing, compared to dsGFP-injected controls. These results extend PmRuvbl1 functions as a putative regulator of P. maidis reproduction and demonstrate the potential of Ruvbl1 to be further exploited as a target for RNAi-mediated insect control.

molecular biology↗

bioRxiv2023

Exportin 1 is required for the reproduction and maize mosaic virus accumulation in its insect vector Peregrinus maidis

Exportin 1 (XPO1) is the major karyopherin-{beta} nuclear receptor mediating the nuclear export of hundreds of proteins and some classes of RNA and regulates several critical processes in the cell, including but not limited to, cell-cycle progression, transcription, translation, oncogenesis and longevity. Viruses have co-opted XPO1 to promote nucleocytoplasmic transport of viral proteins and RNA. Maize mosaic virus (MMV) is an Alphanucleorhabdovirus transmitted in a circulative propagative manner by the corn planthopper, Peregrinus maidis. MMV replicates in the nucleus of plant and insect hosts, and it remains unknown whether MMV co-opts P. maidis XPO1 (PmXPO1) to complete its life cycle. Because XPO1 plays multiple regulatory roles in cell functions and virus infection, we hypothesized that RNAi-mediated silencing of XPO1 would simultaneously and negatively affect MMV accumulation and insect physiology. Although PmXPO1 expression was not modulated during MMV infection, PmXPO1 knockdown negatively affected MMV accumulation in P. maidis at 12 and 15 days after microinjection. Likewise, PmXPO1 knockdown negatively affected P. maidis survival and reproduction. PmXPO1 exhibited tissue specific expression patterns with higher expression in the ovaries compared to the guts of adult females. Survival rate was significantly lower for PmXPO1 knockdown females, compared to controls, but no effect was observed for males. Adult females with PmXPO1 knockdown were heavier and had a larger abdomen compared to controls at 4, 8 and 12 days after dsRNA microinjection. Consistent with an increase in weight, glyceride content specifically and significantly increased in PmXPO1 knockdown female planthoppers. Ovary development was significantly inhibited, and mature eggs were not observed in adult females with PmXPO1 knockdown. Consistent with a major role of PmXPO1 in ovary function and egg production, oviposition and egg hatch in plants was dramatically reduced in dsRNA PmXPO1 treated insects compared with control. Altogether, these results suggest that PmXPO1 is a positive regulator of P. maidis reproduction and that it plays a proviral role in the insect vector supporting MMV infection.

molecular biology↗

bioRxiv2022

Rescue of the first Alphanucleorhabdovirus entirely from cloned complementary DNA: an efficient vector for systemic expression of foreign genes in maize and insect vectors.

Recent reverse genetics technologies have enabled genetic manipulation of plant negative-strand RNA virus (NSR) genomes. Here, we report construction of an infectious clone for the maize-infecting Alphanucleorhabdovirus maydis, the first efficient NSR vector for maize. The full-length infectious clone was established using agrobacterium-mediated delivery of full-length maize mosaic virus (MMV) antigenomic RNA and the viral core proteins (nucleoprotein N, phosphoprotein P, and RNA-directed RNA polymerase L) required for viral transcription and replication into Nicotiana benthamiana. Insertion of intron 2 ST-LS1 into the viral L gene increased stability of the infectious clone in Escherichia coli and Agrobacterium tumefaciens. To monitor virus infection in vivo, a GFP gene was inserted in between the N and P gene junctions to generate recombinant MMV-GFP. cDNA clones of MMV-WT and MMV-GFP replicated in single cells of agroinfiltrated N. benthamiana. Uniform systemic infection and high GFP expression were observed in maize inoculated with extracts of the infiltrated N. benthamiana leaves. Insect vectors supported virus infection when inoculated via feeding on infected maize or microinjection. Both MMV-WT and MMV-GFP were efficiently transmitted to maize by planthopper vectors. The GFP reporter gene was stable in the virus genome and expression remained high over three cycles of transmission in plants and insects. The MMV infectious clone will be a versatile tool for expression of proteins of interest in maize and cross-kingdom studies of virus replication in plant and insect hosts.

plant biology↗

bioRxiv2020

Ever-increasing viral diversity associated with the red imported fire ant Solenopsis invicta (Formicidae: Hymenoptera)

BackgroundAdvances in sequencing and analysis tools have facilitated discovery of many new viruses from invertebrates, including ants. Solenopsis invicta is an invasive ant that has quickly spread around world causing significant ecological and economic impacts. Its virome has begun to be characterized pertaining to potential use of viruses as natural enemies. Although the S. invicta virome is best characterized among ants, most studies have been performed in its native range, with little information from invaded areas. MethodsUsing a metatranscriptome approach, we further characterized viruses associated with S. invicta, in two introduced areas, U.S and Taiwan. The data set used here was obtained from different stages (larvae, pupa, and adults) of S. invicta life cycle. Publicly available RNA sequences from GenBanks Sequence Read Archive were downloaded and de novo assembled using CLC Genomics Workbench 20.0.1. Contigs were compared against the non-redundant protein sequences and those showing similarity to viral sequences were further analyzed. ResultsWe characterized five putative new viruses associated with S. invicta transcriptomes. Sequence comparisons revealed extensive divergence across ORFs and genomic regions with most of them sharing less than 40% amino acid identity with those closest homologous sequences previously characterized. The first negative-sense single-stranded RNA viruses included in the orders Bunyavirales and Mononegavirales are reported. In addition, two positive single-strand viruses and one single strand DNA virus were also characterized. While the presence of a putative tenuivirus associated with S. invicta was previously suggested to be a contamination, here we characterized and present strong evidence that Solenopsis invicta virus 14 (SINV-14) is a tenui-like virus that has a long-term association with the ant. Furthermore, based on virus abundance compared to housekeeping genes, phylogenetic relationships, and completeness of viral coding sequences, our results suggest that four of five viruses reported, those being SINV-14, SINV-15, SINV-16 and SINV-17, replicate in the ant S. invicta. ConclusionsThe present study expands our knowledge about viral diversity associated with S. invicta in introduced areas with potential to be used as biological control agents, which will require further biological characterization.

microbiology↗