@article{rajabu_dallas_chiunga_de leon_ateka_tairo_ndunguru_ascencio-ibanez_hanley-bowdoin_2023, title={SEGS-1 a cassava genomic sequence increases the severity of African cassava mosaic virus infection in <i>Arabidopsis</i> thaliana}, volume={14}, ISSN={["1664-462X"]}, DOI={10.3389/fpls.2023.1250105}, abstractNote={Cassava is a major crop in Sub-Saharan Africa, where it is grown primarily by smallholder farmers. Cassava production is constrained by Cassava mosaic disease (CMD), which is caused by a complex of cassava mosaic begomoviruses (CMBs). A previous study showed that SEGS-1 (sequences enhancing geminivirus symptoms), which occurs in the cassava genome and as episomes during viral infection, enhances CMD symptoms and breaks resistance in cassava. We report here that SEGS-1 also increases viral disease severity in Arabidopsis thaliana plants that are co-inoculated with African cassava mosaic virus (ACMV) and SEGS-1 sequences. Viral disease was also enhanced in Arabidopsis plants carrying a SEGS-1 transgene when inoculated with ACMV alone. Unlike cassava, no SEGS-1 episomal DNA was detected in the transgenic Arabidopsis plants during ACMV infection. Studies using Nicotiana tabacum suspension cells showed that co-transfection of SEGS-1 sequences with an ACMV replicon increases viral DNA accumulation in the absence of viral movement. Together, these results demonstrated that SEGS-1 can function in a heterologous host to increase disease severity. Moreover, SEGS-1 is active in a host genomic context, indicating that SEGS-1 episomes are not required for disease enhancement.}, journal={FRONTIERS IN PLANT SCIENCE}, author={Rajabu, Cyprian A. and Dallas, Mary M. and Chiunga, Evangelista and De Leon, Leandro and Ateka, Elijah M. and Tairo, Fred and Ndunguru, Joseph and Ascencio-Ibanez, Jose T. and Hanley-Bowdoin, Linda}, year={2023}, month={Oct} }
 @article{peng_dallas_ascencio-ibanez_hoyer_legg_hanley-bowdoin_grieve_yin_2022, title={Early detection of plant virus infection using multispectral imaging and spatial-spectral machine learning}, volume={12}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-022-06372-8}, abstractNote={AbstractCassava brown streak disease (CBSD) is an emerging viral disease that can greatly reduce cassava productivity, while causing only mild aerial symptoms that develop late in infection. Early detection of CBSD enables better crop management and intervention. Current techniques require laboratory equipment and are labour intensive and often inaccurate. We have developed a handheld active multispectral imaging (A-MSI) device combined with machine learning for early detection of CBSD in real-time. The principal benefits of A-MSI over passive MSI and conventional camera systems are improved spectral signal-to-noise ratio and temporal repeatability. Information fusion techniques further combine spectral and spatial information to reliably identify features that distinguish healthy cassava from plants with CBSD as early as 28 days post inoculation on a susceptible and a tolerant cultivar. Application of the device has the potential to increase farmers’ access to healthy planting materials and reduce losses due to CBSD in Africa. It can also be adapted for sensing other biotic and abiotic stresses in real-world situations where plants are exposed to multiple pest, pathogen and environmental stresses.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Peng, Yao and Dallas, Mary M. and Ascencio-Ibanez, Jose T. and Hoyer, J. Steen and Legg, James and Hanley-Bowdoin, Linda and Grieve, Bruce and Yin, Hujun}, year={2022}, month={Feb} }
 @article{aimone_de leon_dallas_ndunguru_ascencio-ibanez_hanley-bowdoin_2021, title={A New Type of Satellite Associated with Cassava Mosaic Begomoviruses}, volume={95}, ISSN={["1098-5514"]}, DOI={10.1128/JVI.00432-21}, abstractNote={Cassava is an important root crop in the developing world and a food and income crop for more than 300 million African farmers. Cassava is rising in global importance and trade as the demands for biofuels and commercial starch increase.}, number={21}, journal={JOURNAL OF VIROLOGY}, author={Aimone, Catherine D. and De Leon, Leandro and Dallas, Mary M. and Ndunguru, Joseph and Ascencio-Ibanez, Jose T. and Hanley-Bowdoin, Linda}, year={2021}, month={Nov} }
 @article{hoyer_fondong_dallas_aimone_deppong_duffy_hanley-bowdoin_2020, title={Deeply Sequenced Infectious Clones of Key Cassava Begomovirus Isolates from Cameroon}, volume={9}, ISSN={["2576-098X"]}, DOI={10.1128/MRA.00802-20}, abstractNote={We deeply sequenced two pairs of widely used infectious clones (4 plasmids) of the bipartite begomoviruses African cassava mosaic virus (ACMV) and East African cassava mosaic Cameroon virus (EACMCV). The ACMV clones were quite divergent from published sequences. Raw reads, consensus plasmid sequences, and the infectious clones themselves are all publicly available.}, number={46}, journal={MICROBIOLOGY RESOURCE ANNOUNCEMENTS}, author={Hoyer, J. Steen and Fondong, Vincent N. and Dallas, Mary M. and Aimone, Catherine Doyle and Deppong, David O. and Duffy, Siobain and Hanley-Bowdoin, Linda}, year={2020}, month={Nov} }
 @article{shen_dallas_goshe_hanley-bowdoin_2014, title={SnRK1 Phosphorylation of AL2 Delays Cabbage Leaf Curl Virus Infection in Arabidopsis}, volume={88}, ISSN={["1098-5514"]}, DOI={10.1128/jvi.00761-14}, abstractNote={ABSTRACT
          
            Geminivirus AL2/C2 proteins play key roles in establishing infection and causing disease in their plant hosts. They are involved in viral gene expression, counter host defenses by suppressing transcriptional gene silencing, and interfere with the host signaling involved in pathogen resistance. We report here that begomovirus and curtovirus AL2/C2 proteins interact strongly with host geminivirus Rep-interacting kinases (GRIKs), which are upstream activating kinases of the protein kinase SnRK1, a global regulator of energy and nutrient levels in plants. We used an
            in vitro
            kinase system to show that GRIK-activated SnRK1 phosphorylates recombinant AL2/C2 proteins from several begomoviruses and to map the SnRK1 phosphorylation site to serine-109 in the AL2 proteins of two New World begomoviruses:
            Cabbage Leaf Curl Virus
            (CaLCuV)
            and
            Tomato mottle virus
            . A CaLCuV AL2 S109D phosphomimic mutation did not alter viral DNA levels in protoplast replication assays. In contrast, the phosphomimic mutant was delayed for symptom development and viral DNA accumulation during infection of
            Arabidopsis thaliana
            , demonstrating that SnRK1 contributes to host defenses against CaLCuV. Our observation that serine-109 is not conserved in all AL2/C2 proteins that are SnRK1 substrates
            in vitro
            suggested that phosphorylation of viral proteins by plant kinases contributes to the evolution of geminivirus-host interactions.
          
          
            IMPORTANCE
            Geminiviruses are single-stranded DNA viruses that cause serious diseases in many crops. Dicot-infecting geminiviruses carry genes that encode multifunctional AL2/C2 proteins that are essential for infection. However, it is not clear how AL2/C2 proteins are regulated. Here, we show that the host protein kinase SnRK1, a central regulator of energy balance and nutrient metabolism in plants, phosphorylates serine-109 in AL2 proteins of three subgroups of New World begomoviruses, resulting in a delay in viral DNA accumulation and symptom appearance. Our results support SnRK1's antiviral role and reveal a novel mechanism underlying this function. Phylogenetic analysis suggested that AL2 S109 evolved as begomoviruses migrated from the Old World to the New World and may have provided a selective advantage as begomoviruses adapted to a different environment and different plant hosts. This study provides new insights into the interaction of viral pathogens with their plant hosts at the level of viral protein modification by the host.
          }, number={18}, journal={JOURNAL OF VIROLOGY}, author={Shen, Wei and Dallas, Mary Beth and Goshe, Michael B. and Hanley-Bowdoin, Linda}, year={2014}, month={Sep}, pages={10598–10612} }
 @article{reyes_nash_dallas_ascencio-ibanez_hanley-bowdoin_2013, title={Peptide Aptamers That Bind to Geminivirus Replication Proteins Confer a Resistance Phenotype to Tomato Yellow Leaf Curl Virus and Tomato Mottle Virus Infection in Tomato}, volume={87}, ISSN={["1098-5514"]}, DOI={10.1128/jvi.01095-13}, abstractNote={ABSTRACT
          
            Geminiviruses constitute a large family of single-stranded DNA viruses that cause serious losses in important crops worldwide. They often exist in disease complexes and have high recombination and mutation rates, allowing them to adapt rapidly to new hosts and environments. Thus, an effective resistance strategy must be general in character and able to target multiple viruses. The geminivirus replication protein (Rep) is a good target for broad-based disease control because it is highly conserved and required for viral replication. In an earlier study, we identified a set of peptide aptamers that bind to Rep and reduce viral replication in cultured plant cells. In this study, we selected 16 of the peptide aptamers for further analysis in yeast two-hybrid assays. The results of these experiments showed that all 16 peptide aptamers interact with all or most of the Rep proteins from nine viruses representing the three major
            Geminiviridae
            genera and identified two peptide aptamers (A22 and A64) that interact strongly with different regions in the Rep N terminus. Transgenic tomato lines expressing A22 or A64 and inoculated with
            Tomato yellow leaf curl virus
            or
            Tomato mottle virus
            exhibited delayed viral DNA accumulation and often contained lower levels of viral DNA. Strikingly, the effect on symptoms was stronger, with many of the plants showing no symptoms or strongly attenuated symptoms. Together, these results established the efficacy of using Rep-binding peptide aptamers to develop crops that are resistant to diverse geminiviruses.
          }, number={17}, journal={JOURNAL OF VIROLOGY}, author={Reyes, Maria Ines and Nash, Tara E. and Dallas, Mary M. and Ascencio-Ibanez, J. Trinidad and Hanley-Bowdoin, Linda}, year={2013}, month={Sep}, pages={9691–9706} }
 @article{sanchez-duran_dallas_ascencio-ibanez_reyes_arroyo-mateos_ruiz-albert_hanley-bowdoin_bejarano_2011, title={Interaction between Geminivirus Replication Protein and the SUMO-Conjugating Enzyme Is Required for Viral Infection}, volume={85}, ISSN={["1098-5514"]}, DOI={10.1128/jvi.02566-10}, abstractNote={ABSTRACT
          Geminiviruses are small DNA viruses that replicate in nuclei of infected plant cells by using plant DNA polymerases. These viruses encode a protein designated AL1, Rep, or AC1 that is essential for viral replication. AL1 is an oligomeric protein that binds to double-stranded DNA, catalyzes the cleavage and ligation of single-stranded DNA, and induces the accumulation of host replication machinery. It also interacts with several host proteins, including the cell cycle regulator retinoblastoma-related protein (RBR), the DNA replication protein PCNA (proliferating cellular nuclear antigen), and the sumoylation enzyme that conjugates SUMO to target proteins (SUMO-conjugating enzyme [SCE1]). The SCE1-binding motif was mapped by deletion to a region encompassing AL1 amino acids 85 to 114. Alanine mutagenesis of lysine residues in the binding region either reduced or eliminated the interaction with SCE1, but no defects were observed for other AL1 functions, such as oligomerization, DNA binding, DNA cleavage, and interaction with AL3 or RBR. The lysine mutations reduced or abolished virus infectivity in plants and viral DNA accumulation in transient-replication assays, suggesting that the AL1-SCE1 interaction is required for viral DNA replication. Ectopic AL1 expression did not result in broad changes in the sumoylation pattern of plant cells, but specific changes were detected, indicating that AL1 modifies the sumoylation state of selected host proteins. These results established the importance of AL1-SCE1 interactions during geminivirus infection of plants and suggested that AL1 alters the sumoylation of selected host factors to create an environment suitable for viral infection.}, number={19}, journal={JOURNAL OF VIROLOGY}, author={Sanchez-Duran, Miguel A. and Dallas, Mary B. and Ascencio-Ibanez, Jose T. and Reyes, Maria Ines and Arroyo-Mateos, Manuel and Ruiz-Albert, Javier and Hanley-Bowdoin, Linda and Bejarano, Eduardo R.}, year={2011}, month={Oct}, pages={9789–9800} }