Insights into and Liberibacter solanacearum interaction: a tissue-specific transcriptomic approach.

The tomato-potato psyllid, (Šulc), belonging to the Hemiptera order, is an insect pest of solanaceous crops and vectors a fastidious bacterium, Liberibacter solanacearum (Lso), the presumptive causal agent of zebra chip and vein greening diseases in potatoes and tomatoes, respectively. The genome of has been sequenced recently, providing new avenues to elucidate mechanistic insights into pathogenesis in vegetable crops. In this study, we performed RNA-sequencing of the critical psyllid organs (salivary glands and ovaries) involved in Lso pathology and transmission to host plants.

Identification and Characterization of Potato Zebra Chip Resistance Among Wild Species.

Potato zebra chip (ZC) disease, associated with the uncultured phloem-limited bacterium, Liberibacter solanacearum (Lso), is transmitted by the potato psyllid . Potato ZC disease poses a significant threat to potato production worldwide. Current management practices mainly rely on the control of the psyllid to limit the spread of Lso.

Genome-wide association study and genomic prediction of white rust resistance in USDA GRIN spinach germplasm.

White rust, caused by , is one of the major yield-limiting diseases of spinach () in some major commercial production areas, particularly in southern Texas in the United States. The use of host resistance is the most economical and environment-friendly approach to managing white rust in spinach production. The objectives of this study were to conduct a genome-wide associating study (GWAS), to identify single nucleotide polymorphism (SNP) markers associated with white rust resistance in spinach, and to perform genomic prediction (GP) to estimate the prediction accuracy (PA).

Phenotypic Diversity and Association Mapping of Ascorbic Acid Content in Spinach.

Ascorbic acid (AsA), or vitamin C, is an essential nutrient for humans. In plants, AsA functions as an antioxidant during normal metabolism or in response to stress. Spinach is a highly nutritious green leafy vegetable that is consumed fresh, cooked or as a part of other dishes.

Persistence of the Exotic Mirid (Hemiptera: Miridae) in South Texas.

The Rio Grande Valley is one of the most productive agricultural areas in the U.S and is located in the southernmost part of Texas. In October 2013, we detected an exotic plant bug, Reuter (Hemiptera: Miridae: Bryocorinae) occurring in the region.

Potato Zebra Chip: An Overview of the Disease, Control Strategies, and Prospects.

Potato ( L.) is an important food crop worldwide. As the demand for fresh and processed potato products is increasing globally, there is a need to manage and control devastating diseases such as zebra chip (ZC).

Genome-wide simple sequence repeats (SSR) markers discovered from whole-genome sequence comparisons of multiple spinach accessions.

The availability of well-assembled genome sequences and reduced sequencing costs have enabled the resequencing of many additional accessions in several crops, thus facilitating the rapid discovery and development of simple sequence repeat (SSR) markers. Although the genome sequence of inbred spinach line Sp75 is available, previous efforts have resulted in a limited number of useful SSR markers. Identification of additional polymorphic SSR markers will support genetics and breeding research in spinach.

Selection of nitrogen responsive root architectural traits in spinach using machine learning and genetic correlations.

The efficient acquisition and transport of nutrients by plants largely depend on the root architecture. Due to the absence of complex microbial network interactions and soil heterogeneity in a restricted soilless medium, the architecture of roots is a function of genetics defined by the soilless matrix and exogenously supplied nutrients such as nitrogen (N). The knowledge of root trait combinations that offer the optimal nitrogen use efficiency (NUE) is far from being conclusive.

Production system influences tomato phenolics and indoleamines in a cultivar-specific manner.

Tomato (Solanum lycopersicum) fruit is a rich source of health-promoting compounds, and epidemiological studies show that tomato consumption may reduce the risk of chronic diseases. This study compared the effect of genotype, production system, and their interaction on eight tomato varieties grown in the open-field (OF) or net-house (NH), a structure completely covered with a 50-mesh screen to reduce pest and wind damage, in South Texas. The NH structure reduced solar radiation up to ~30% and decreased wind speed by 6.

Fatty Acid Desaturases in the Chloroplast and Endoplasmic Reticulum Promote Susceptibility to the Green Peach Aphid in .

Fatty acid desaturases (FADs) in plants influence levels of susceptibility to multiple stresses, including insect infestations. In this study, populations of the green peach aphid () on were reduced by mutations in three desaturases: , which encodes a chloroplastic stearoyl-[acyl-carrier-protein] 9-desaturase, and or which encode ω-3 FADs in the chloroplast and endoplasmic reticulum (ER), respectively. These data indicate that certain FADs promote susceptibility to aphids and that aphids are impacted by desaturases in both the chloroplast and ER.

Plant hairy roots enable high throughput identification of antimicrobials against Candidatus Liberibacter spp.

A major bottleneck in identifying therapies to control citrus greening and other devastating plant diseases caused by fastidious pathogens is our inability to culture the pathogens in defined media or axenic cultures. As such, conventional approaches for antimicrobial evaluation (genetic or chemical) rely on time-consuming, low-throughput and inherently variable whole-plant assays. Here, we report that plant hairy roots support the growth of fastidious pathogens like Candidatus Liberibacter spp.

Effects of genotype and production system on quality of tomato fruits and in vitro bile acids binding capacity.

Tomato is an important source of health-promoting constituents, and researchers have focused on enhancing the content. In the present study, the influence of net-house (NH) and open-field (OF) growing conditions on physicochemical traits of tomatoes from eight different cultivars were evaluated. The tomato fruit qualities, such as color, total soluble solids (TSS), total acidity (TA), and pH were measured.

Developing Growth-Associated Molecular Markers Via High-Throughput Phenotyping in Spinach.

High-throughput imaging and genomic information can be combined to optimize marker development. Genome-wide association studies identified loci associated with plant growth traits. We identified candidate genes associated with plant growth and development.

Tomato Metabolic Changes in Response to Tomato-Potato Psyllid () and Its Vectored Pathogen Liberibacter solanacearum.

The bacterial pathogen ' Liberibacter solanacearum' (Lso) is transmitted by the tomato potato psyllid (TPP), , to solanaceous crops. In the present study, the changes in metabolic profiles of insect-susceptible (cv CastleMart) and resistant (RIL LA3952) tomato plants in response to TPP vectoring Lso or not, were examined after 48 h post infestation. Non-volatile and volatile metabolites were identified and quantified using headspace solid-phase microextraction equipped with a gas chromatograph-mass spectrometry (HS-SPME/GC-MS) and ultra-high pressure liquid chromatography coupled to electrospray quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS), respectively.

Stability of yield and its components in grafted tomato tested across multiple environments in Texas.

Grafting with vigorous rootstocks could offer tomato growers in Texas sustainable and efficient option to achieve reliable yield across a range of production systems and locations. Genotypes (G) of grafted and non-grafted tomato were grown in different environments (E) in the 2017 and 2018 spring seasons. The objectives of the study were to (i) evaluate the effects of production system and grafting on tomato yield traits, (ii) determine the size of genotypic and genotype by environment interaction (G × E) variance components, and (iii) evaluate the relative stability of tested genotypes for yield and its components across production environments.

Effect of production system and inhibitory potential of aroma volatiles on polyphenol oxidase and peroxidase activity in tomatoes.

Background: Polyphenol oxidase (PPO) and peroxidase (POD) are key enzymes associated with shelf life and defense responses. Thus, the activity of PPO and POD enzymes is usually assessed to check the quality of food samples and to understand the physiological responses of plants to different stresses. However, the outcomes of PPO and POD activity assessment studies are highly dependent on assay conditions.

Minor alleles are associated with white rust () susceptibility in spinach ().

Minor alleles (MA) have been associated with disease incidence in human studies, enabling the identification of diagnostic risk factors for various diseases. However, allelic mapping has rarely been performed in plant systems. The goal of this study was to determine whether a difference in MA prevalence is a strong enough risk factor to indicate a likely significant difference in disease resistance against white rust (WR; ) in spinach ().

Bactericera cockerelli resistance in the wild tomato Solanum habrochaites is polygenic and influenced by the presence of Candidatus Liberibacter solanacearum.

The tomato-potato psyllid (TPP), Bactericera cockerelli, is a vector for the phloem-limited bacterium Candidatus Liberibacter solanacearum (Lso), the causative agent of economically important diseases including tomato vein-greening and potato zebra chip. Here, we screened 11 wild tomato relatives for TPP resistance as potential resources for tomato (Solanum lycopersicum) cultivar development. Six accessions with strong TPP resistance (survival <10%) were identified within S.

Metabolomic studies of volatiles from tomatoes grown in net-house and open-field conditions.

In the present study, the influence of production systems (net-house and open-field) on volatile profiles of three Texas A&M University (TAMU) and five commercial tomato varieties was investigated. Forty metabolites were determined using headspace solid phase microextraction (HS-SPME) equipped with gas chromatography and mass spectrometry (GC-MS). The data was evaluated by multivariate analyses to discriminate the effects of genotype and production system, and to identify potential biomarker(s).

A Comparison of the Effects of and on Plant-Aphid Interactions.

The mutation in tomato (), which disrupts function of FATTY ACID DESATURASE 7 (FAD7), confers resistance to the potato aphid () and modifies the plant’s C6 volatile profiles. To investigate whether C6 volatiles play a role in resistance, (), which encodes a critical enzyme in C6 volatile synthesis, was silenced in wild-type tomato plants and mutants. Silencing in wild-type tomato increased potato aphid host preference and reproduction on 5-week old plants but had no influence on 3-week old plants.

Reproducible genomic DNA preparation from diverse crop species for molecular genetic applications.

Background: Several high-throughput molecular genetic analyses rely on high-quality genomic DNA. Copurification of other molecules can negatively impact the functionality of plant DNA preparations employed in these procedures. Isolating DNA from agronomically important crops, such as sugarcane, rice, citrus, potato and tomato is a challenge due to the presence of high fiber, polysaccharides, or secondary metabolites.

The ethylene response factor Pti5 contributes to potato aphid resistance in tomato independent of ethylene signalling.

Ethylene response factors (ERFs) comprise a large family of transcription factors that regulate numerous biological processes including growth, development, and response to environmental stresses. Here, we report that Pti5, an ERF in tomato [Solanum lycopersicum (Linnaeus)] was transcriptionally upregulated in response to the potato aphid Macrosiphum euphorbiae (Thomas), and contributed to plant defences that limited the population growth of this phloem-feeding insect. Virus-induced gene silencing of Pti5 enhanced aphid population growth on tomato, both on an aphid-susceptible cultivar and on a near-isogenic genotype that carried the Mi-1.

Expression of α-DIOXYGENASE 1 in tomato and Arabidopsis contributes to plant defenses against aphids.

Plant α-dioxygenases (α-DOX) are fatty acid-hydroperoxidases that contribute to the synthesis of oxylipins, a diverse group of compounds primarily generated through oxidation of linoleic (LA) and linolenic acid (LNA). Oxylipins are implicated in plant signaling against biotic and abiotic stresses. We report here that the potato aphid (Macrosiphum euphorbiae) induces Slα-DOX1 but not Slα-DOX2 expression in tomato (Solanum lycopersicum).

Regulation of inflammatory chemokine receptors on blood T cells associated to the circulating versus liver chemokines in dengue fever.

Little is known about the role of chemokines/chemokines receptors on T cells in natural DENV infection. Patients from DENV-2 and -3- outbreaks were studied prospectively during the acute or convalescent phases. Expression of chemokine receptor and activation markers on lymphocyte subpopulations were determined by flow cytometry analysis, plasma chemokine ligands concentrations were measured by ELISA and quantification of CCL5/RANTES(+) cells in liver tissues from fatal dengue cases was performed by immunochemistry.