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PubMed1994

Transgenic tomato plants expressing the tomato yellow leaf curl virus capsid protein are resistant to the virus.

The tomato yellow leaf curl virus (TYLCV) gene that encodes the capsid protein (V1) was placed under transcriptional control of the cauliflower mosaic virus 35S promoter and cloned into an Agrobacterium Ti-derived plasmid and used to transform plants from an interspecific tomato hybrid, Lycopersicon esculentum X L. pennellii (F1), sensitive to the TYLCV disease. When transgenic F1 plants, expressing the V1 gene, were inoculated with TYLCV using whiteflies fed on TYLCV-infected plants, they responded either as untransformed tomato or showed expression of delayed disease symptoms and recovery from the disease with increasingly more resistance upon repeated inoculation. Transformed plants that were as sensitive to inoculation as untransformed controls expressed the V1 gene at the RNA level only. All the transformed plants that recovered from disease expressed the TYLCV capsid protein.

Base Sequence↗

PubMed2004

Potato aphid, Macrosiphum euphorbiae (Thomas), in tomatoes: plant canopy distribution and binomial sampling on processing tomatoes in California.

A binomial sampling method for the potato aphid, Macrosiphum euphorbiae (Thomas), on processing tomato plants, Lycopersicon esculentum (Mill), is proposed. Relationships between mean number of M. euphorbiae per leaf and proportion of leaves infested [P(I)] with M. euphorbiae for both upper and interior leaves of the processing tomato varieties 'Alta' and 'Halley' are presented. A split-plot design was used with variety, position in the plant canopy, and block as the factors examined through linear regression and analysis of variance (ANOVA). Results supported the hypotheses that M. euphorbiae densities on upper canopy leaves are predictive of densities on inner canopy leaves and that proportion of M. euphorbiae infested leaves are predictive of mean densities per leaf. Mean M. euphorbiae density was greater on 'Alta' than 'Halley' tomato plants, supporting the assumption that 'Alta' is the more susceptible variety. Taylor's Power Law coefficients, a and b, were similar for proportion of M. euphorbiae-infested upper and inner leaves of both 'Alta' and 'Halley'. Taylor's b coefficients ranged from 1.57 to 1.74, indicating a highly clumped distribution for M. euphorbiae.

Animals↗

PubMed2004

Tomato psyllid behavioral responses to tomato plant lines and interactions of plant lines with insecticides.

Adult tomato psyllid, Bactericerca (Paratrioza) cockerelli (Sulc) (Homoptera: Psyllidae), behavioral responses were evaluated for five tomato plant lines and for the interactions of insecticides with four commercial cultivars. Plant lines tested included the commercial 'Shady Lady', 'Yellow Pear', '7718 VFN', 'QualiT 21', and the plant introduction line PI 134417. Insecticides included a kaolin particle film, pymetrozine, pyriproxyfen, spinosad, and imidacloprid. Psyllids spent significantly more time feeding on 'Yellow Pear' than all other plant lines except '7718 VFN'. In comparisons among plant lines, psyllids exposed to the wild accession PI 1.34417 showed a 98% reduction in feeding, a significant increase in jumping behavior, and a significant tendency to abandon the leaves, thereby demonstrating repellency, not just an antixenosis response. Interactions between plant lines and insecticides influenced behavioral responses. All insecticides tested significantly reduced feeding durations on all cultivars except the preferred 'Yellow Pear'. However, nonfeeding activities such as walking, probing, resting, and jumping varied substantially with chemical and cultivar combination. The behavior assay results offered insight into host resistance mechanisms, provided a useful technique for measuring effects of interaction of plant lines with insecticides, and generated information for selecting insecticides for specific cultivars used in integrated pest management program for the tomato psyllid.

Animals↗

PubMed1996

Musculoskeletal problems in the tomato growing industry: 'tomato trainer's shoulder'?

Tomato training entails highly repetitive shoulder muscle contractions, static contractions and work at shoulder level, factors linked in other working groups with neck and shoulder complaints. The frequency of musculoskeletal complaints was compared using the Nordic Questionnaire in 56 tomato trainers and 52 other matched glasshouse workers whose job did not include these work task factors. A higher 12- month (odds ratio (OR) = 5.9; [95% confidence interval (CI) = 2.4-16.7] and 7- day (OR = 3.6, CI = 1.2-11.1) period prevalence of shoulder complaint was recorded in trainers than in pickers and deleafers. Other upper limb and upper trunk complaints were also more common in tomato trainers, highlighting an area of ergonomic concern.

Adult↗

PubMed2001

Overexpression of Pti5 in tomato potentiates pathogen-induced defense gene expression and enhances disease resistance to Pseudomonas syringae pv. tomato.

The tomato Pti5 gene encodes a pathogen-inducible ethylene response element-binding protein-like transcription factor that interacts with the disease resistance gene product Pto. Overexpression of Pti5 or Pti5-VP16, a translational fusion with a constitutive transcriptional activation domain, in tomato enhanced resistance to Pseudomonas syringae pv. tomato. Constitutive expression of Pti5 or Pti5-VP16 did not affect the basal level of pathogenesis-related gene expression, but it accelerated pathogen-induced expression of GluB and Catalase. The results demonstrate a positive role of Pti5 in defense gene regulation and disease resistance and suggest that a pathogen-activated posttranscriptional regulatory step is necessary for the pathogen induction of the defense gene expression.

DNA-Binding Proteins↗

PubMed2001

Overcoming host- and pathogen-mediated resistance in tomato and tobacco maps to the M RNA of Tomato spotted wilt virus.

A viral genetic system was used to map the determinants of the ability of Tomato spotted wilt virus (TSWV) to overcome the R gene (Sw-5) in tomato and the resistance conferred by the nucleocapsid gene of TSWV (N gene) in tobacco. A complete set of reassortant genotypes was generated from TSWV isolates A and D. TSWV-A was able to overcome the Sw-5 gene in tomato and the TSWV N gene in tobacco, whereas TSWV-D was repressed by both forms of resistance. The ability to overcome both forms of resistance was associated with the M RNA segment of TSWV-A (M(A)). Overcoming the Sw-5 gene was linked solely to the presence of M(A), and the ability of M(A) to overcome the TSWV N gene was modified by the L RNA and the S RNA of TSWV-A, which is consistent with previous reports that suggest that the nucleocapsid gene is not the primary determinant for overcoming the nucleocapsid-mediated resistance. Sequence analysis of the M RNA segment of TSWV-A, -D, and the type isolate BR-01 revealed multiple differences in the coding and noncoding regions, which prevented identification of the resistance-breaking nucleotide sequences.

Bunyaviridae↗

PubMed2002

Overexpression of the tomato Asc-1 gene mediates high insensitivity to AAL toxins and fumonisin B1 in tomato hairy roots and confers resistance to Alternaria alternata f. sp. lycopersici in Nicotiana umbratica plants.

The sphinganine-analog mycotoxins (SAMs) fumonisin B1 and AAL toxins are inhibitors of eukaryotic sphinganine N-acyltransferase in vitro. Treatment of eukaryotes with SAMs generally results in an accumulation of sphingoid base precursors and a depletion of complex sphingolipids. The asc,asc genotypes of tomato (Lycopersicon esculentum) and Nicotiana umbratica are sensitive to SAMs and host of the AAL toxin-producing fungus Alternaria alternata f. sp. lycopersici. Codominant insensitivity to SAMs in tomato is mediated by the Asc-1 gene, and sensitivity is associated with a frame-shift mutation present in asc-1. We investigated the function of Asc-1 in mediating insensitivity to SAMs and resistance to the fungus by overexpression of asc-1 and Asc-1. In this study, it is shown that overexpression of these genes did not lead to visual symptoms in tomato hairy roots and N. umbratica plants. Overexpression of asc-1 did not influence the (in)sensitivity to SAMs. Overexpression of Asc-1 in SAM-sensitive hairy roots and N. umbratica plants, however, mediated a high insensitivity to SAMs and resistance to plant infection by Alternaria alternata f. sp. lycopersici.

Alternaria↗

PubMed1997

Amino acid changes in the putative replicase of tomato mosaic tobamovirus that overcome resistance in Tm-1 tomato.

Replacement of Gln-979 by Glu in the putative replicase of tomato mosaic tobamovirus is sufficient to overcome Tm-1 resistance in tomato. It has been suggested that this change decreases the local net charge of the protein which is important in overcoming the resistance. In this study, we constructed five mutants, designated TLAsn, TLAsp, TLHis, TLLys and TLArg, in which Gln-979 was replaced by Asn, Asp, His, Lys and Arg, respectively, and analysed their abilities to overcome Tm-1 resistance. Unexpectedly, not only TLAsp, but also TLLys multiplied in tomato cells with the Tm-1 gene. TLAsn and TLArg multiplied at a reduced level. Multiplication of TLHis was virtually almost inhibited. From these results, it is unlikely that a decrease in the local net charge is the major reason for overcoming Tm-1 resistance.

Base Sequence↗

PubMed1975

Comparison between Biosynthesis of ent-Kaurene in Germinating Tomato Seeds and Cell Suspension Cultures of Tomato and Tobacco.

Biosynthesis of ent-kaurene was investigated in extracts of cell suspension cultures derived from tobacco callus (Nicotiana tabacum L.), tomato callus (Solanum lycopersicum L.), and in germinating tomato seeds. Incubation of extracts derived from the two cell cultures with either isopentenyl pyrophosphate-(14)C or with (14)C-labeled mevalonate, followed by alkaline phosphatase hydrolysis, resulted in the formation of trans-geranylgeraniol-(14)C and trans-farnesol-(14)C. The corresponding pyrophosphates of trans-geranyl-geraniol-(14)C and trans-farnesol-(14)C were also detected. No detectable amount of ent-kaurene-(14)C was produced by these enzymatic preparations when trans-geranylgeranyl-(14)C pyrophosphate served as substrate. However, copalyl-(14)C pyrophosphate served as a substrate for the production of ent-kaurene. Cell-free extracts derived from germinating tomato seeds catalyzed the formation of ent-kaurene-(14)C from mevalonate-(14)C, isopentenyl-(14)C pyrophosphate, trans-geranylgeranyl-(14)C pyrophosphate, and copalyl-(14)C pyrophosphate.

Journal Article↗

PubMed1991

Molecular cloning of tomato pectin methylesterase gene and its expression in rutgers, ripening inhibitor, nonripening, and never ripe tomato fruits.

We have purified pectin methylesterase (PME; EC 3.1.11) from mature green (MG) tomato (Lycopersicon esculentum Mill. cv Rutgers) pericarp to an apparent homogeneity, raised antibodies to the purified protein, and isolated a PME cDNA clone from a lambdagtll expression library constructed from MG pericarp poly(A)(+) RNA. Based on DNA sequencing, the PME cDNA clone isolated in the present study is different from that cloned earlier from cv Ailsa Craig (J Ray et al. [1989] Eur J Biochem 174:119-124). PME antibodies and the cDNA clone are used to determine changes in PME gene expression in developing fruits from normally ripening cv Rutgers and ripening-impaired mutants ripening inhibitor (rin), nonripening (nor), and never ripe (Nr). In Rutgers, PME mRNA is first detected in 15-day-old fruit, reaches a steady-state maximum between 30-day-old fruit and MG stage, and declines thereafter. PME activity is first detectable at day 10 and gradually increases until the turning stage. The increase in PME activity parallels an increase in PME protein; however, the levels of PME protein continue to increase beyond the turning stage while PME activity begins to decline. Patterns of PME gene expression in nor and Nr fruits are similar to the normally ripening cv Rutgers. However, the rin mutation has a considerable effect on PME gene expression in tomato fruits. PME RNA is not detectable in rin fruits older than 45 days and PME activity and protein begin showing a decline at the same time. Even though PME activity levels comparable to 25-day-old fruit were found in root tissue of normal plants, PME protein and mRNA are not detected in vegetative tissues using PME antibodies and cDNA as probes. Our data suggest that PME expression in tomato pericarp is highly regulated during fruit development and that mRNA synthesis and stability, protein stability, and delayed protein synthesis influence the level of PME activity in developing fruits.

Journal Article↗

PubMed2004

High-resolution fine mapping and fluorescence in situ hybridization analysis of sun, a locus controlling tomato fruit shape, reveals a region of the tomato genome prone to DNA rearrangements.

The locus sun on the short arm of tomato chromosome 7 controls morphology of the fruit. Alleles from wild relatives impart a round shape, while alleles from certain cultivated varieties impart an oval shape typical of roma-type tomatoes. We fine mapped the locus in two populations and investigated the genome organization of the region spanning and flanking sun. The first high-resolution genetic map of the sun locus was constructed using a nearly isogenic F(2) population derived from a cross between Lycopersicon pennellii introgression line IL7-4 and L. esculentum cv Sun1642. The mapping combined with results from pachytene FISH experiments demonstrated that the top of chromosome 7 is inverted in L. pennellii accession LA716. sun was located close to the chromosomal breakpoint and within the inversion, thereby precluding map-based cloning of the gene using this population. The fruit-shape locus was subsequently fine mapped in a population derived from a cross between L. esculentum Sun1642 and L. pimpinellifolium LA1589. Chromosome walking using clones identified from several large genomic insert libraries resulted in two noncontiguous contigs flanking sun. Fiber-FISH analysis showed that distance between the two contigs measured 68 kb in L. esculentum Sun1642 and 38 kb in L. pimpinellifolium LA1589, respectively. The sun locus mapped between the two contigs, suggesting that allelic variation at this locus may be due to an insertion/deletion event. The results demonstrate that sun is located in a highly dynamic region of the tomato genome.

Chromosome Mapping↗

PubMed2001

The effectiveness of ecologically acceptable ways of protection of field-grown tomato (Lycopersicon lycopersicum (L.) Karsten) from tomato late blight (Phytophthora infestans (Mont.) de Bary) in extreme weather conditions.

During the extremely wet vegetation season in 1999 the efficiency of protection of two cultivars of field grown tomato (Lycopersicon lycopersicum (L.) Karsten), 'Pick Rite' and 'GO 101', against tomato late blight (Phytophthora infestans (Mont.) de Bary) using three ecologically acceptable growing techniques and agrochemical measures (growing on black plastic mulch with no fungicides used, spraying with Dithane M-45 (mancozeb), spraying with Cuprablau-Z (Cu-hydroxide) and control) have been studied. It was found out that under such extreme weather conditions none of these measures can ensure an adequate protection of tomato. The highest yield of healthy fruits (0.30 kg per plant) was obtained after a threefold spraying with Dithane M-45 (mancozeb), the highest percentage of non infected fruits (38.1%) after a twofold spraying with Cuprablau-Z (Cu-hydroxide). The black plastic mulch, used with the intention to reduce the plant contact with the potential inoculum in the soil proved to be ineffective.

Agriculture↗

PubMed2003

Selection of tomato plants resistant to a local Polish isolate of tomato spotted wilt virus (TSWV).

We found that the Sw-5 gene confers resistance to one of the Polish isolates of tomato spotted wilt virus (TSWV). A series of tomato breeding accessions was analysed along with standards of resistance and susceptibility to TSWV. The presence of the Sw-5 gene was determined using the available PCR marker. Subsequently plants from these accessions were grown in the presence of the TSWV isolate from Poland. Some of them developed severe symptoms of the TSWV disease. Expression of the virus proteins was also assayed in tissues of the investigated plants. We found general agreement between either lack or presence of the disease symptoms, virus proteins and resistance gene. Some observed discrepancies of these data are also discussed. Our results indicate that marker-assisted selection can be used for breeding of the TSWV-resistant tomato in Poland.

Enzyme-Linked Immunosorbent Assay↗

PubMedDate not supplied

Liquid chromatographic determination of tenuazonic acid and alternariol methyl ether in tomatoes and tomato products.

A liquid chromatographic (LC) method for determining tenuazonic acid (TA) and alternariol methyl ether (AME) in tomatoes and tomato products is described. The Alternaria metabolites are extracted from a water slurry of the sample with CHCl3, the mixture is centrifuged, and the extract is fractionated on a silica gel column. Reverse phase LC with an ultraviolet detector (for TA) and a fluorescence detector (for AME) connected in series is used for final separation and determination. The limit of determination for TA and AME is 25 and 3 ng/g, respectively, with average recoveries from catsup of 83 and 68%, respectively. The LC method also detects alternariol, but interfering peaks in some samples prevent accurate quantitation. Chemical ionization mass spectrometry (CIMS) is used to confirm TA. Samples (142) of tomatoes collected from commercial processing lines were analyzed; TA was found in 73 samples (0.4-70 micrograms/g).

Alternaria↗

PubMed1978

[Behavior of Ethephon residues on tomatoes. Part I. Green house tomatoes].

The preparation Flordimex, which contains Ethephon (2-chloroethanephosphonic acid) as the active ingredient, is used for accelerating the ripening of tomatoes. During the years 1974--1977, tomato samples from 89 experiments were tested for Ethephon residues. The determination was performed gas chromatographically using alkali flame ionization detector as 2-chloroethanephosphonic acid dimethyl ester; the detection limit of the method was 0.01 mg/kg. The observed results must be evaluated on the basis of the permissible value (1 mg/kg) stipulated for vegetables by the Ministry of Health of the GDR. 1--2 days after the use of concentrations of 0.1%, 0.2%, 0.3% and 0.4%, respectively, the following mean residue values were found: 0.31, 0.50, 0.39 and 0.91 mg/kg, respectively, which decreased but slowly. This leads to the conclusion that formulation concentrations of more than 0.3% and applications of more than 6 1/ha should not be allowed by the Ministry. In case of repeated uses, 3-week intervals are imperative. Under the above-mentioned conditions of use, the mean residue values determined 4--5 days after application approximated 0.6 mg/kg. This period is to be regarded as a tentative waiting-period that must be respected after the treatment of glasshouse tomatoes with Flordimex.

Chromatography, Gas↗

PubMed1990

Infection of tomato by the tomato yellow leaf curl virus: susceptibility to infection, symptom development, and accumulation of viral DNA.

Symptom development in tomato plants following whitefly-mediated inoculation with tomato yellow leaf curl virus (TYLCV) was related to the occurrence of viral DNA using a specific DNA probe. Although disease symptoms were first observed 15 days post-inoculation, viral DNA could be detected 7 days earlier. TYLCV-DNA concentrations reached an optimum 4 days before symptoms appeared. The highest concentrations of TYLCV-DNA were found in rapidly growing tissues (shoot apex, young leaves, roots) and in the stems; the lowest concentrations were found in the older leaves and cotyledons. Plants were also inoculated on specific sites. Young leaves and apices were the best targets for virus inoculation. In these tissues, the viral DNA replicated at the site of inoculation and was transported first to the roots, then to the shoot apex and to the neighboring leaves and the flowers. Inoculation through the oldest leaves was inefficient.

DNA Probes↗

PubMed1997

Map-based cloning of the tomato genomic region that spans the Sw-5 tospovirus resistance gene in tomato.

Two yeast artificial chromosomes (YACs) containing genomic DNA from tomato have been isolated using CT220, an RFLP marker which is tightly linked to the tomato spotted wilt virus resistance gene, Sw-5. High-resolution mapping of the YAC ends and internal YAC probes demonstrated that one of the YAC clones, TY257 (400 kb), spans Sw-5. By chromosome walking in a cosmid library, the position of Sw-5 has been delimited within the YAC to a maximal chromosomal segment of 100 kb, spanned by nine overlapping cosmid clones.

Chromosome Mapping↗

PubMed2007

Identification and characterisation of tomato torrado virus, a new plant picorna-like virus from tomato.

A new virus was isolated from tomato plants from the Murcia region in Spain which showed symptoms of 'torrado disease'; very distinct necrotic, almost burn-like symptoms on leaves of infected plants. The virus particles are isometric with a diameter of approximately 28 nm. The viral genome consists of two (+)ssRNA molecules of 7793 (RNA1) and 5389 nts (RNA2). RNA1 contains one open reading frame (ORF) encoding a predicted polyprotein of 241 kDa that shows conserved regions with motifs typical for a protease-cofactor, a helicase, a protease and an RNA-dependent RNA polymerase. RNA2 contains two, partially overlapping ORFs potentially encoding proteins of 20 and 134 kDa. These viral RNAs are encapsidated by three proteins with estimated sizes of 35, 26 and 23 kDa. Direct protein sequencing mapped these coat proteins to ORF2 on RNA2. Phylogenetic analyses of nucleotide and derived amino acid sequences showed that the virus is related to but distinct from viruses belonging to the genera Sequivirus, Sadwavirus and Cheravirus. This new virus, for which the name tomato torrado virus is proposed, most likely represents a member of a new plant virus genus.

Amino Acid Motifs↗