Resistance to the insect vector enhances the robustness and durability of tomato yellow leaf curl virus resistance conferred by .

Tomato yellow leaf curl virus (TYLCV) is a begomovirus (genus , family ) transmitted persistently by the whitefly . It causes tomato yellow leaf curl disease (TYLCD), resulting in significant yield losses worldwide. TYLCD is controlled mainly by using F1 hybrid tomato cultivars harboring the TYLCV resistance gene .

Induction of Glandular Trichomes to Control in Tomato Crops: Modulation by the Natural Enemy .

Whitefly-transmitted viruses are one of the biggest threats to tomato () growing worldwide. Strategies based on the introgression of resistance traits from wild relatives are promoted to control tomato pests and diseases. Recently, a trichome-based resistance characterizing the wild species was introgressed into a cultivated tomato.

Crinivirus Tomato Chlorosis Virus Compromises the Control of Tomato Yellow Leaf Curl Virus in Tomato Plants by the Gene.

Tomato yellow leaf curl disease (TYLCD) causes severe damage to tomato crops in warm regions of the world, and is associated with infections of several whitefly ()-transmitted single-stranded (ss)DNA begomoviruses (genus , family ). The most widespread begomovirus isolates associated with TYLCD are those of the type strain of the species, known as Israel (TYLCV-IL). The gene is widely used in commercial tomato cultivars to control TYLCV-IL damage, providing resistance to the virus by restricting viral accumulation and tolerance to TYLCD by inhibiting disease symptoms.

Begomovirus Tomato Leaf Curl New Delhi Virus Is Seedborne but Not Seed Transmitted in Melon.

Seed transmission can be of considerable relevance to the dissemination of plant viruses in nature and for their prevalence and perpetuation. Long-distance spread of isolates of the begomovirus species (genus , family ) has recently occurred from Asia to the Middle East and the Mediterranean Basin. Here, we investigated the possible transmission by melon ( L.

Host Plant Resistance to to Control Damage Caused in Tomato Plants by the Emerging Crinivirus Tomato Chlorosis Virus.

Tomato chlorosis virus (genus , family ) (ToCV) is rapidly emerging, causing increased damage to tomato production worldwide. The virus is transmitted in a semipersistent manner by several whitefly (Hemiptera: Aleyrodidae) species and is expanding its geographical and host ranges associated with the emergence of whiteflies of the complex. Control is based essentially on intensive insecticide applications against the insect vector but is largely ineffective.

An Acylsucrose-Producing Tomato Line Derived from the Wild Species Decreases Fitness of the Whitefly .

A combination of biological control and host plant resistance would be desirable for optimally controlling the greenhouse whitefly, in tomato crops. Whitefly settlement preference, oviposition, and survivorship were evaluated on ABL 10-4 and 'Moneymaker', two nearly-isogenic tomato lines with, and without, whitefly-resistance traits based on type IV leaf glandular trichomes derived from the tomato wild species , respectively. Significantly reduced preference of adult whiteflies for ABL 10-4 leaves was observed.

Revisiting Seed Transmission of the Type Strain of in Tomato Plants.

Isolates of the (TYLCV) species (genus , family ) infect tomato crops worldwide, causing severe economic damage. Members of the whitefly sibling species group are the vector of begomoviruses, including TYLCV. However, transmission of isolates of the type strain (Israel [IL]) of TYLCV (TYLCV-IL) by tomato seed has recently been reported based on infections occurring in Korea.

Use of Systemic Acquired Resistance and Whitefly Optical Barriers to Reduce Tomato Yellow Leaf Curl Disease Damage to Tomato Crops.

Epidemics of tomato yellow leaf curl disease (TYLCD) caused by tomato yellow leaf curl-like begomoviruses (genus , family ) severely damage open field and protected tomato crops worldwide. Intensive application of insecticides against the whitefly vector is generally used as control strategy to reduce TYLCD impact. This practice, however, is frequently ineffective and has a negative impact on the environment and human health.

Tomato Yellow Leaf Curl Sardinia Virus, a Species Evolving by Mutation and Recombination: A Challenge for Virus Control.

The tomato leaf curl disease (TYLCD) is associated with infections of several species of begomoviruses (genus , family ) and causes severe damage to tomatoes throughout tropical and sub-tropical regions of the world. Among others, the (TYLCSV) species causes damage in the Mediterranean Basin since early outbreaks occurred. Nevertheless, scarce information is available about the diversity of TYLCSV.

World Management of Geminiviruses.

Management of geminiviruses is a worldwide challenge because of the widespread distribution of economically important diseases caused by these viruses. Regardless of the type of agriculture, management is most effective with an integrated pest management (IPM) approach that involves measures before, during, and after the growing season. This includes starting with resistant cultivars and virus- and vector-free transplants and propagative plants.

Differential Shape of Geminivirus Mutant Spectra Across Cultivated and Wild Hosts With Invariant Viral Consensus Sequences.

Geminiviruses (family ) possess single-stranded circular DNA genomes that are replicated by cellular polymerases in plant host cell nuclei. In their hosts, geminivirus populations behave as ensembles of mutant and recombinant genomes, known as viral quasispecies. This favors the emergence of new geminiviruses with altered host range, facilitating new or more severe diseases or overcoming resistance traits.

Alphasatellitidae: a new family with two subfamilies for the classification of geminivirus- and nanovirus-associated alphasatellites.

Nanoviruses and geminiviruses are circular, single stranded DNA viruses that infect many plant species around the world. Nanoviruses and certain geminiviruses that belong to the Begomovirus and Mastrevirus genera are associated with additional circular, single stranded DNA molecules (~ 1-1.4 kb) that encode a replication-associated protein (Rep).

The Heterologous Expression of the p22 RNA Silencing Suppressor of the Crinivirus Tomato Chlorosis Virus from Tobacco Rattle Virus and Potato Virus X Enhances Disease Severity but Does Not Complement Suppressor-Defective Mutant Viruses.

To counteract host antiviral RNA silencing, plant viruses express suppressor proteins that function as pathogenicity enhancers. The genome of the Tomato chlorosis virus (ToCV) (genus , family ) encodes an RNA silencing suppressor, the protein p22, that has been described as having one of the longest lasting local suppressor activities when assayed in . Since suppression of RNA silencing and the ability to enhance disease severity are closely associated, we analyzed the effect of expressing p22 in heterologous viral contexts.

Tomato Leaf Curl New Delhi Virus: An Emerging Virus Complex Threatening Vegetable and Fiber Crops.

The tomato leaf curl New Delhi virus (ToLCNDV) (genus , family ) represents an important constraint to tomato production, as it causes the most predominant and economically important disease affecting tomato in the Indian sub-continent. However, in recent years, ToLCNDV has been fast extending its host range and spreading to new geographical regions, including the Middle East and the western Mediterranean Basin. Extensive research on the genome structure, protein functions, molecular biology, and plant-virus interactions of ToLCNDV has been conducted in the last decade.

ICTV Virus Taxonomy Profile: Geminiviridae.

The geminiviruses are a family of small, non-enveloped viruses with single-stranded, circular DNA genomes of 2500-5200 bases. Geminiviruses are transmitted by various types of insect (whiteflies, leafhoppers, treehoppers and aphids). Members of the genus Begomovirus are transmitted by whiteflies, those in the genera Becurtovirus, Curtovirus, Grablovirus, Mastrevirus and Turncurtovirus are transmitted by specific leafhoppers, the single member of the genus Topocuvirus is transmitted by a treehopper and one member of the genus Capulavirus is transmitted by an aphid.

Capulavirus and Grablovirus: two new genera in the family Geminiviridae.

Geminiviruses are plant-infecting single-stranded DNA viruses that occur in most parts of the world. Currently, there are seven genera within the family Geminiviridae (Becurtovirus, Begomovirus, Curtovirus, Eragrovirus, Mastrevirus, Topocuvirus and Turncurtovirus). The rate of discovery of new geminiviruses has increased significantly over the last decade as a result of new molecular tools and approaches (rolling-circle amplification and deep sequencing) that allow for high-throughput workflows.

A Jasmonate-Inducible Defense Trait Transferred from Wild into Cultivated Tomato Establishes Increased Whitefly Resistance and Reduced Viral Disease Incidence.

Whiteflies damage tomatoes mostly via the viruses they transmit. Cultivated tomatoes lack many of the resistances of their wild relatives. In order to increase protection to its major pest, the whitefly and its transmitted (TYLCV), we introgressed a trichome-based resistance trait from the wild tomato into cultivated tomato, .

A Novel Strain of Tomato Leaf Curl New Delhi Virus Has Spread to the Mediterranean Basin.

Tomato leaf curl New Delhi virus (ToLCNDV) is a whitefly-transmitted bipartite begomovirus (genus , family ) that causes damage to multiple cultivated plant species mainly belonging to the and families. ToLCNDV was limited to Asian countries until 2012, when it was first reported in Spain, causing severe epidemics in cucurbit crops. Here, we show that a genetically-uniform ToLCNDV population is present in Spain, compatible with a recent introduction.

Tomato yellow leaf curl virus: No evidence for replication in the insect vector Bemisia tabaci.

Begomovirus ssDNA plant virus (family Geminiviridae) replication within the Bemisia tabaci vector is controversial. Transovarial transmission, alteration to whitefly biology, or detection of viral transcripts in the vector are proposed as indirect evidence of replication of tomato yellow leaf curl virus (TYLCV). Recently, contrasting direct evidence has been reported regarding the capacity of TYLCV to replicate within individuals of B.

The p22 RNA Silencing Suppressor of the Crinivirus Tomato chlorosis virus is Dispensable for Local Viral Replication but Important for Counteracting an Antiviral RDR6-Mediated Response during Systemic Infection.

Among the components of the RNA silencing pathway in plants, RNA-dependent RNA polymerases (RDRs) play fundamental roles in antiviral defence. Here, we demonstrate that the Nicotiana benthamiana RDR6 is involved in defence against the bipartite crinivirus (genus Crinivirus, family Closteroviridae) Tomato chlorosis virus (ToCV). Additionally, by producing a p22-deficient ToCV infectious mutant clone (ToCVΔp22), we studied the role of this viral suppressor of RNA silencing in viral infection in both wild-type and RDR6-silenced N.

Begomovirus-Associated Satellite DNA Diversity Captured Through Vector-Enabled Metagenomic (VEM) Surveys Using Whiteflies (Aleyrodidae).

Monopartite begomoviruses (Geminiviridae), which are whitefly-transmitted single-stranded DNA viruses known for causing devastating crop diseases, are often associated with satellite DNAs. Since begomovirus acquisition or exchange of satellite DNAs may lead to adaptation to new plant hosts and emergence of new disease complexes, it is important to investigate the diversity and distribution of these molecules. This study reports begomovirus-associated satellite DNAs identified during a vector-enabled metagenomic (VEM) survey of begomoviruses using whiteflies collected in various locations (California (USA), Guatemala, Israel, Puerto Rico, and Spain).

The p22 RNA silencing suppressor of the crinivirus Tomato chlorosis virus preferentially binds long dsRNAs preventing them from cleavage.

Viruses encode silencing suppressor proteins to counteract RNA silencing. Because dsRNA plays a key role in silencing, a general silencing suppressor strategy is dsRNA binding. The p22 suppressor of the plant virus Tomato chlorosis virus (ToCV; genus Crinivirus, family Closteroviridae) has been described as having one of the longest lasting local suppressor activities.

Vector-Enabled Metagenomic (VEM) Surveys Using Whiteflies (Aleyrodidae) Reveal Novel Begomovirus Species in the New and Old Worlds.

Whitefly-transmitted viruses belonging to the genus Begomovirus (family Geminiviridae) represent a substantial threat to agricultural food production. The rapid evolutionary potential of these single-stranded DNA viruses combined with the polyphagous feeding behavior of their whitefly vector (Bemisia tabaci) can lead to the emergence of damaging viral strains. Therefore, it is crucial to characterize begomoviruses circulating in different regions and crops globally.

Genetic diversity and silencing suppression activity of the p22 protein of Tomato chlorosis virus isolates from tomato and sweet pepper.

As for other bipartite criniviruses (genus Crinivirus, family Closteroviridae), the genome of Tomato chlorosis virus encodes an RNA silencing suppressor, the protein p22, in the 3'-proximal region of RNA1. This protein has been reported as having one of the longest lasting local suppressor activities when transiently expressed in Nicotiana benthamiana. Here, we examined the genetic diversity of the p22 gene in ToCV isolates from tomato and sweet pepper.

Recessive Resistance Derived from Tomato cv. Tyking-Limits Drastically the Spread of Tomato Yellow Leaf Curl Virus.

The tomato yellow leaf curl disease (TYLCD) causes severe damage to tomato (Solanum lycopersicum L.) crops throughout tropical and subtropical regions of the world. TYLCD is associated with a complex of single-stranded circular DNA plant viruses of the genus Begomovirus (family Geminiviridae) transmitted by the whitefy Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae).