Engineering aphid transmission of foxtail mosaic virus in the presence of potyvirus helper component proteinase through coat protein modifications.

Biotechnologies that use plant viruses as plant enhancement tools have shown great potential to flexibly engineer crop traits, but field applications of these technologies are still limited by efficient dissemination methods. Potyviruses can be rapidly inoculated into plants by aphid vectors due to the presence of the potyviral helper component proteinase (HC-Pro), which binds to the DAG motif of the coat protein (CP) of the virion. Previously it was determined that a naturally occurring DAG motif in the non-aphid-transmissible potexvirus, potato aucuba mosaic virus (PAMV), is functional when a potyviral HC-Pro is provided to aphids in plants.

The Potyviral Protein 6K2 from Turnip Mosaic Virus Increases Plant Resilience to Drought.

Virus infection can increase drought tolerance of infected plants compared with noninfected plants; however, the mechanisms mediating virus-induced drought tolerance remain unclear. In this study, we demonstrate turnip mosaic virus (TuMV) infection increases survival under drought compared with uninfected plants. To determine if specific TuMV proteins mediate drought tolerance, we cloned the coding sequence for each of the major viral proteins and generated transgenic that constitutively express each protein.

Spatiotemporal dynamics of the tomato fruit transcriptome under prolonged water stress.

Water availability influences all aspects of plant growth and development; however, most studies of plant responses to drought have focused on vegetative organs, notably roots and leaves. Far less is known about the molecular bases of drought acclimation responses in fruits, which are complex organs with distinct tissue types. To obtain a more comprehensive picture of the molecular mechanisms governing fruit development under drought, we profiled the transcriptomes of a spectrum of fruit tissues from tomato (Solanum lycopersicum), spanning early growth through ripening and collected from plants grown under varying intensities of water stress.

The Potyviral Protein 6K1 Reduces Plant Proteases Activity during Infection.

Potyviral genomes encode just 11 major proteins and multifunctionality is associated with most of these proteins at different stages of the virus infection cycle. Some potyviral proteins modulate phytohormones and protein degradation pathways and have either pro- or anti-viral/insect vector functions. Our previous work demonstrated that the potyviral protein 6K1 has an antagonistic effect on vectors when expressed transiently in host plants, suggesting plant defenses are regulated.

Effector-mediated plant-virus-vector interactions.

Hemipterans (such as aphids, whiteflies, and leafhoppers) are some of the most devastating insect pests due to the numerous plant pathogens they transmit as vectors, which are primarily viral. Over the past decade, tremendous progress has been made in broadening our understanding of plant-virus-vector interactions, yet on the molecular level, viruses and vectors have typically been studied in isolation of each other until recently. From that work, it is clear that both hemipteran vectors and viruses use effectors to manipulate host physiology and successfully colonize a plant and that co-evolutionary dynamics have resulted in effective host immune responses, as well as diverse mechanisms of counterattack by both challengers.

Potato leafroll virus reduces Buchnera aphidocola titer and alters vector transcriptome responses.

Viruses in the Luteoviridae family, such as Potato leafroll virus (PLRV), are transmitted by aphids in a circulative and nonpropagative mode. This means the virions enter the aphid body through the gut when they feed from infected plants and then the virions circulate through the hemolymph to enter the salivary glands before being released into the saliva. Although these viruses do not replicate in their insect vectors, previous studies have demonstrated viruliferous aphid behavior is altered and the obligate symbiont of aphids, Buchnera aphidocola, may be involved in transmission.

XAP5 CIRCADIAN TIMEKEEPER Affects Both DNA Damage Responses and Immune Signaling in .

Numerous links have been reported between immune response and DNA damage repair pathways in both plants and animals but the precise nature of the relationship between these fundamental processes is not entirely clear. Here, we report that XAP5 CIRCADIAN TIMEKEEPER (XCT), a protein highly conserved across eukaryotes, acts as a negative regulator of immunity in and plays a positive role in responses to DNA damaging radiation. We find mutants have enhanced resistance to infection by a virulent bacterial pathogen, pv.

Acylsugars protect Nicotiana benthamiana against insect herbivory and desiccation.

Nicotiana benthamiana acylsugar acyltransferase (ASAT) is required for protection against desiccation and insect herbivory. Knockout mutations provide a new resource for investigation of plant-aphid and plant-whitefly interactions. Nicotiana benthamiana is used extensively as a transient expression platform for functional analysis of genes from other species.

Responses of pea plants to multiple antagonists are mediated by order of attack and phytohormone crosstalk.

Plants are often attacked by multiple antagonists and traits of the attacking organisms and their order of arrival onto hosts may affect plant defences. However, few studies have assessed how multiple antagonists, and varying attack order, affect plant defence or nutrition. To address this, we assessed defensive and nutritional responses of Pisum sativum plants after attack by a vector herbivore (Acrythosiphon pisum), a nonvector herbivore (Sitona lineatus), and a pathogen (Pea enation mosaic virus, PEMV).

Responses to predation risk cues and alarm pheromones affect plant virus transmission by an aphid vector.

Herbivores assess predation risk in their environment by identifying visual, chemical, and tactile predator cues. Detection of predator cues can induce risk-avoidance behaviors in herbivores that affect feeding, dispersal, and host selection in ways that minimize mortality and reproductive costs. For herbivores that transmit plant pathogens, including many aphids, changes in herbivore behavior in response to predator cues may also affect pathogen spread.

Interspecific interactions within a vector-borne complex are influenced by a co-occurring pathosystem.

Potato virus Y (PVY) and zebra chip (ZC) disease are major threats to solanaceous crop production in North America. PVY can be spread by aphid vectors and through vegetative propagation in potatoes. ZC is associated with "Candidatus Liberibacter solanacearum" (Lso), which is transmitted by the tomato/potato psyllid, Bactericera cockerelli Šulc (Hemiptera: Triozidae).

Host susceptibility factors render ripe tomato fruit vulnerable to fungal disease despite active immune responses.

The increased susceptibility of ripe fruit to fungal pathogens poses a substantial threat to crop production and marketability. Here, we coupled transcriptomic analyses with mutant studies to uncover critical processes associated with defense and susceptibility in tomato (Solanum lycopersicum) fruit. Using unripe and ripe fruit inoculated with three fungal pathogens, we identified common pathogen responses reliant on chitinases, WRKY transcription factors, and reactive oxygen species detoxification.

Plant Immune System Activation Upon Citrus Leprosis Virus C Infection Is Mimicked by the Ectopic Expression of the P61 Viral Protein.

Citrus leprosis virus C (CiLV-C, genus , family ) is an atypical virus that does not spread systemically in its plant hosts. Upon its inoculation by mites, only localized lesions occur, and the infection remains limited to cells around mite feeding sites. Here, we aimed to gain insights into the putative causes of viral unfitness in plants by expanding the limited knowledge of the molecular mechanisms underlying plant/kitavirid interactions.

Organic management promotes natural pest control through altered plant resistance to insects.

Reduced insect pest populations found on long-term organic farms have mostly been attributed to increased biodiversity and abundance of beneficial predators, as well as to changes in plant nutrient content. However, the role of plant resistance has largely been ignored. Here, we determine whether host plant resistance mediates decreased pest populations in organic systems and identify potential underpinning mechanisms.

A polerovirus, Potato leafroll virus, alters plant-vector interactions using three viral proteins.

Potato leafroll virus (PLRV), genus Polerovirus, family Luteoviridae, is a major pathogen of potato worldwide. PLRV is transmitted among host plants by aphids in a circulative-nonpropagative manner. Previous studies have demonstrated that PLRV infection increases aphid fecundity on, and attraction to, infected plants as compared to controls.

Effects of Agricultural Management on Rhizosphere Microbial Structure and Function in Processing Tomato Plants.

Agricultural management practices affect bulk soil microbial communities and the functions they carry out, but it remains unclear how these effects extend to the rhizosphere in different agroecosystem contexts. Given close linkages between rhizosphere processes and plant nutrition and productivity, understanding how management practices impact this critical zone is of great importance to optimize plant-soil interactions for agricultural sustainability. A comparison of six paired conventional-organic processing tomato farms was conducted to investigate relationships between management, soil physicochemical parameters, and rhizosphere microbial community composition and functions.

Ethylene signaling mediates potyvirus spread by aphid vectors.

Plant pathogens can influence host characteristics such as volatile emissions, nutrient composition or plant color, modulating vector and non-vector insect dynamics in the ecosystem. While previous research has focused on insect attraction and dispersal to infected plants, little is known about mechanisms mediating these interactions. Here, we investigate the role of ethylene in green peach aphid (Myzus persicae) attraction to potyvirus-infected plants.

Network Analysis Reveals a Role for Salicylic Acid Pathway Components in Shade Avoidance.

Plants have sophisticated mechanisms for sensing neighbor shade. To maximize their ability to compete for light, plants respond to shade through enhanced elongation and physiological changes. The shade avoidance response affects many different organs and growth stages, yet the signaling pathways underlying this response have mostly been studied in seedlings.

Making a Better Home: Modulation of Plant Defensive Response by Mites.

False-spider mites of the genus are highly polyphagous pests that attack hundreds of plant species of distinct families worldwide. Besides causing direct damage, these mites may also act as vectors of many plant viruses that threaten high-value ornamental plants like orchids and economically important crops such as citrus and coffee. To better understand the molecular mechanisms behind plant-mite interaction we used an RNA-Seq approach to assess the global response of (Arabidopsis) plants along the course of the infestation with , the main vector species within the genus.

Reciprocal plant-mediated interactions between a virus and a non-vector herbivore.

Vector-borne viruses alter many physical and chemical traits of their plant hosts, indirectly affecting the fitness and behavior of vectors in ways that promote virus transmission. However, it is unclear whether viruses induce plant-mediated shifts in the behavior and fitness of non-vector herbivores, or if non-vectors affect the dynamics of vector-borne viruses. Here we evaluated reciprocal interactions between Pea enation mosaic virus (PEMV), a pathogen transmitted by the aphid Acrythosiphon pisum, and a non-vector weevil, Sitona lineatus.

A viral protease relocalizes in the presence of the vector to promote vector performance.

Vector-borne pathogens influence host characteristics relevant to host-vector contact, increasing pathogen transmission and survival. Previously, we demonstrated that infection with Turnip mosaic virus, a member of one of the largest families of plant-infecting viruses, increases vector attraction and reproduction on infected hosts. These changes were due to a single viral protein, NIa-Pro.

Vector-Borne Bacterial Plant Pathogens: Interactions with Hemipteran Insects and Plants.

Hemipteran insects are devastating pests of crops due to their wide host range, rapid reproduction, and ability to transmit numerous plant-infecting pathogens as vectors. While the field of plant-virus-vector interactions has flourished in recent years, plant-bacteria-vector interactions remain poorly understood. Leafhoppers and psyllids are by far the most important vectors of bacterial pathogens, yet there are still significant gaps in our understanding of their feeding behavior, salivary secretions, and plant responses as compared to important viral vectors, such as whiteflies and aphids.

A novel virus from Macrosiphum euphorbiae with similarities to members of the family Flaviviridae.

A virus with a large genome was identified in the transcriptome of the potato aphid (Macrosiphum euphorbiae) and was named Macrosiphum euphorbiae virus 1 (MeV-1). The MeV-1 genome is 22 780 nt in size, including 3' and 5' non-coding regions, with a single large ORF encoding a putative polyprotein of 7333 aa. The C-terminal region of the predicted MeV-1 polyprotein contained sequences with similarities to helicase, methyltransferase and RNA-dependent RNA polymerase (RdRp) motifs, while the N-terminal region lacked any motifs including structural proteins.