Amesuviridae: a new family of plant-infecting viruses in the phylum Cressdnaviricota, realm Monodnaviria.

The phylum Cressdnaviricota comprises viruses with single-stranded, circular DNA genomes that encode an HUH-type endonuclease (known as Rep). The phylum includes two classes, eight orders, and 11 families. Here, we report the creation of a twelfth family in the order Mulpavirales, class Arfiviricetes of the phylum Cressdnaviricota. The family Amesuviridae comprises viruses that infect plants and is divided into two genera: Temfrudevirus, including the species Temfrudevirus temperatum (with temperate fruit decay-associated virus as a member), and Yermavirus, including the species Yermavirus ilicis (with yerba mate-associated circular DNA virus as a member). Both viruses encode Rep proteins with HUH endonuclease and SH3 superfamily helicase domains. Phylogenetic analysis indicates that the replicative module of amesuviruses constitutes a well-supported monophyletic clade related to Rep proteins from viruses in the order Mulpavirales. Furthermore, both viruses encode a single capsid protein (CP) related to geminivirus CPs. Phylogenetic incongruence between the replicative and structural modules of amesuviruses suggests a chimeric origin resulting from remote recombination events between ancestral mulpavirales and geminivirids. The creation of the family Amesuviridae has been ratified by the International Committee on Taxonomy of Viruses (ICTV).

A systematic review and repeatability study on the use of deep learning for classifying and detecting tuberculosis bacilli in microscopic images.

Tuberculosis (TB) is among the leading causes of death worldwide from a single infectious agent. This disease usually affects the lungs (pulmonary TB) and can be cured in most cases with a quick diagnosis and proper treatment. Microscopic sputum smear is widely used to diagnose and manage pulmonary TB. Despite being relatively fast and low cost, it can be exhausting because it depends on manually counting TB bacilli (Mycobacterium tuberculosis) in microscope images. In this context, different Deep Learning (DL) techniques are proposed in the literature to assist in performing smear microscopy. This article presents a systematic review based on the PRISMA procedure, which investigates which DL techniques can contribute to classifying TB bacilli in microscopic images of sputum smears using the Ziehl-Nielsen method. After an extensive search and a careful inclusion/exclusion procedure, 28 papers were selected from a total of 400 papers retrieved from nine databases. Based on these articles, the DL techniques are presented as possible solutions to improve smear microscopy. The main concepts necessary to understand how such techniques are proposed and used are also presented. In addition, replication work is also carried out, verifying reproducibility and comparing different works in the literature. In this review, we look at how DL techniques can be a partner to make sputum smear microscopy faster and more efficient. We also identify some gaps in the literature that can guide which issues can be addressed in other works to contribute to the practical use of these methods in laboratories.

MicroRNAs expression profiles in early responses to different levels of water deficit in Setaria viridis.

Water deficit is a major constraint for crops of economic importance in almost all agricultural regions. However, plants have an active defense system to adapt to these adverse conditions, acting in the reprogramming of gene expression responsible for encoding microRNAs (miRNAs). These miRNAs promote the regulation to the target gene expression by the post-transcriptional (PTGS) and transcriptional gene silencing (TGS), modulating several pathways including defense response to water deficit. The broader knowledge of the miRNA expression profile and its regulatory networks in response to water deficit can provide evidence for the development of new biotechnological tools for genetic improvement of several important crops. In this study, we used Setaria viridis accession A10.1 as a C4 model plant to widely investigate the miRNA expression profile in early responses to different levels of water deficit. Ecophysiological studies in Setaria viridis under water deficit and after rewatering demonstrated a drought tolerant accession, capable of a rapid recovery from the stress. Deep small RNA sequencing and degradome studies were performed in plants submitted to drought to identify differentially expressed miRNA genes and their predicted targets, using in silico analysis. Our findings showed that several miRNAs were differentially modulated in response to distinctive levels of water deficit and after rewatering. The predicted mRNA targets mainly corresponded to genes related to cell wall remodeling, antioxidant system and drought-related transcription factors, indicating that these genes are rapidly regulated in early responses to drought stress. The implications of these modulations are extensively discussed, and higher-effect miRNAs are suggested as major players for potential use in genetic engineering to improve drought tolerance in economically important crops, such as sugarcane, maize, and sorghum. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01226-z.

A plant-specific syntaxin-6 protein contributes to the intracytoplasmic route for the begomovirus CabLCV.

Because of limited free diffusion in the cytoplasm, viruses must use active transport mechanisms to move intracellularly. Nevertheless, how the plant single-stranded DNA begomoviruses hijack the host intracytoplasmic transport machinery to move from the nucleus to the plasmodesmata remains enigmatic. Here, we identified nuclear shuttle protein (NSP)-interacting proteins from Arabidopsis (Arabidopsis thaliana) by probing a protein microarray and demonstrated that the cabbage leaf curl virus NSP, a facilitator of the nucleocytoplasmic trafficking of viral (v)DNA, interacts in planta with an endosomal vesicle-localized, plant-specific syntaxin-6 protein, designated NSP-interacting syntaxin domain-containing protein (NISP). NISP displays a proviral function, unlike the syntaxin-6 paralog AT2G18860 that failed to interact with NSP. Consistent with these findings, nisp-1 mutant plants were less susceptible to begomovirus infection, a phenotype reversed by NISP complementation. NISP-overexpressing lines accumulated higher levels of vDNA than wild-type. Furthermore, NISP interacted with an NSP-interacting GTPase (NIG) involved in NSP-vDNA nucleocytoplasmic translocation. The NISP-NIG interaction was enhanced by NSP. We also showed that endosomal NISP associates with vDNA. NISP may function as a docking site for recruiting NIG and NSP into endosomes, providing a mechanism for the intracytoplasmic translocation of the NSP-vDNA complex toward and from the cell periphery.

Sugar metabolism and developmental stages of rubber tree (Hevea brasiliensis L.) seeds.

Changes in the concentration of sugars and sucrose metabolism enzymes can characterize the developmental stages of a seed. In recalcitrant species such as Hevea brasiliensis L., little is known about these changes. We aimed to evaluate the three main stages of development of rubber tree seeds - histodifferentiation, cell elongation and accumulation of reserves. The activities of acid and neutral invertases (E.C. 3.2.1.26) and sucrose synthase (EC 2.4.1.13), and the concentrations of reducing sugars (RS), total soluble sugars (TSS) and sucrose (Suc) were determined concomitantly with the histochemical and anatomical evaluation of seed structure. Histodifferentiation in rubber tree seeds occurs up to 75 days after anthesis (DAA). The concentration of RS is high and of Suc is low during seed histodifferentiation, which occurs along with a visible increase in the number of cell divisions. After that period, there is an increase in the concentration of Suc (mg g-1 ) and in the number and size of starch granules, and a decrease in the concentration of RS (mg g-1 ). At that point, cell elongation occurs. At 135 DAA, there is an inversion in the concentration of these two sugars and an increase in reserve accumulation. Thus, in seeds of the evaluated clone, the period up to 75 DAA is characterized as the histodifferentiation stage, while from that time up to 120 DAA the cell elongation stage takes place. The final stage of seed maturation and reserve accumulation begins at 135 DAA, and the seed, including the embryo, is completely formed at 175 DAA.

Genetic variability and population structure of the New World begomovirus Euphorbia yellow mosaic virus.

The emergence of begomoviruses (whitefly-transmitted viruses classified in the genus Begomovirus, family Geminiviridae) in Brazil probably occurred by horizontal transfer from non-cultivated plants after the introduction of Bemisia tabaci MEAM1. The centre of diversity of Euphorbia heterophylla (Euphorbiaceae) is located in Brazil and Paraguay, where it is an invasive species in soybean and other crops. Reports of possible begomovirus infection of E. heterophylla in Brazil date back to the 1950s. In 2011, Euphorbia yellow mosaic virus (EuYMV) was described in symptomatic plants collected in the Brazilian state of Goiás. Here we assess the genetic variability and population structure of begomoviruses infecting E. heterophylla in samples collected throughout nine Brazilian states from 2009 to 2014. A total of 158 and 57 haplotypes were compared in DNA-A and DNA-B datasets, respectively. Analysis comparing population structure in a large sampled area enabled us to differentiate two subpopulations. Further, the application of discriminant analysis of principal components allowed the differentiation of six subpopulations according to sampling locations and in agreement with phylogenetic analysis. In general, negative selection was predominant in all six subpopulations. Interestingly, we were able to reconstruct the phylogeny based on the information from the 23 sites that contributed most to the geographical structure proposed, demonstrating that these polymorphisms hold supporting information to discriminate between subpopulations. These sites were mapped in the genome and compared at the level of amino acid changes, providing insights into how genetic drift and selection contribute to maintain the patterns of begomovirus population variability from a geographical structuring point of view.

The Stress-Induced Soybean NAC Transcription Factor GmNAC81 Plays a Positive Role in Developmentally Programmed Leaf Senescence.

The onset of leaf senescence is a highly regulated developmental change that is controlled by both genetics and the environment. Senescence is triggered by massive transcriptional reprogramming, but functional information about its underlying regulatory mechanisms is limited. In the current investigation, we performed a functional analysis of the soybean (Glycine max) osmotic stress- and endoplasmic reticulum (ER) stress-induced NAC transcription factor GmNAC81 during natural leaf senescence using overexpression studies and reverse genetics. GmNAC81-overexpressing lines displayed accelerated flowering and leaf senescence but otherwise developed normally. The precocious leaf senescence of GmNAC81-overexpressing lines was associated with greater Chl loss, faster photosynthetic decay and higher expression of hydrolytic enzyme-encoding GmNAC81 target genes, including the vacuolar processing enzyme (VPE), an executioner of vacuole-triggered programmed cell death (PCD). Conversely, virus-induced gene silencing-mediated silencing of GmNAC81 delayed leaf senescence and was associated with reductions in Chl loss, lipid peroxidation and the expression of GmNAC81 direct targets. Promoter-reporter studies revealed that the expression pattern of GmNAC81 was associated with senescence in soybean leaves. Our data indicate that GmNAC81 is a positive regulator of age-dependent senescence and may integrate osmotic stress- and ER stress-induced PCD responses with natural leaf senescence through the GmNAC81/VPE regulatory circuit.

A novel, highly divergent ssDNA virus identified in Brazil infecting apple, pear and grapevine.

Fruit trees of temperate and tropical climates are of great economical importance worldwide and several viruses have been reported affecting their productivity and longevity. Fruit trees of different Brazilian regions displaying virus-like symptoms were evaluated for infection by circular DNA viruses. Seventy-four fruit trees were sampled and a novel, highly divergent, monopartite circular ssDNA virus was cloned from apple, pear and grapevine trees. Forty-five complete viral genomes were sequenced, with a size of approx. 3.4 kb and organized into five ORFs. Deduced amino acid sequences showed identities in the range of 38% with unclassified circular ssDNA viruses, nanoviruses and alphasatellites (putative Replication-associated protein, Rep), and begomo-, curto- and mastreviruses (putative coat protein, CP, and movement protein, MP). A large intergenic region contains a short palindromic sequence capable of forming a hairpin-like structure with the loop sequence TAGTATTAC, identical to the conserved nonanucleotide of circoviruses, nanoviruses and alphasatellites. Recombination events were not detected and phylogenetic analysis showed a relationship with circo-, nano- and geminiviruses. PCR confirmed the presence of this novel ssDNA virus in field plants. Infectivity tests using the cloned viral genome confirmed its ability to infect apple and pear tree seedlings, but not Nicotiana benthamiana. The name "Temperate fruit decay-associated virus" (TFDaV) is proposed for this novel virus.