Pot studies on the effects of mycorrhizal root colonization on plant growth and nematode reproduction in tomato-Meloidogyne incognita and carrot-Pratylenchus penetrans pathosystems were carried out. The mycorrhizal fungus Glomus mosseae did not protect tomato plants inoculated with the pathogen M.incognita when it was inoculated simultaneously with the mycorrhiza, as plants inoculated with M.incognita died before harvest. On the other hand, when tomato seedlings were inoculated with the nematode three weeks after mycorrhization, colonization of tomato roots by G. mosseae compensated for the reduction of plant growth caused by M.incognita infection. Tomato shoot weight was 24% greater and gall index 33% lower than plants inoculated with the nematode alone, and final soil densities of M.incognita were reduced by 85% when tomato roots were colonized by the mycorrhiza. Root infection by P.penetrans reduced carrot growth, but soil inoculation with Glomus sp. spores compensated for the damage caused by P.penetrans. Addition of Glomus spores to soil reduced P.penetrans soil densities by 49%.

This study was undertaken to investigate the relevance of tomato allergy in pollen-allergic patients, and to identify and characterize tomato allergens. Therefore, sera of a group of 32 pollen-allergic patients with a history of adverse reactions to tomato were investigated by means of immunoblotting and specific IgE measurements (CAP, EAST, EAST inhibition and CCD [cross-reactive carbohydrate determinants] – ELISA). IgE-reactive spots on 2D blots were analyzed by amino acid microsequencing.Tomato allergy was found to occur with a prevalence of about 9% in our group of birch pollen-allergic patients. Of the patients with adverse reactions to tomato, 44% presented IgE to tomato profilin and 35.5% specific IgE to CCD. Two patients were sensitized to a lipid transfer protein in tomato. Microsequencing of other IgE-reactive proteins, separated by 2D-gel electrophoresis and transferred to PVDF membranes, revealed β-fructofuranosidase, polygalacturonase 2A, and pectinesterase as further tomato allergens. Our data show that tomato is a relevant allergenic food in pollen-allergic patients. It seems that the majority of pollen-associated allergies to tomato is caused by known ubiquitous allergenic structures such as profilin and cross-reactive IgE-binding N-glycans. Furthermore, lipid transfer protein, as well as polygalacturonase 2A, pectinesterase and β-fructofuranosidase may represent birch pollen-independent tomato allergens for certain patients.

Pseudomonas fluorescens FPT9601, a plant growth-promoting rhizobacterium (PGPR) isolated from tomato rhizosphere, can protect tomato (Lycopersicon esculentum Mill) from bacterial wilt disease caused by Ralstonia solanacearum. This strain produces antibiotics 2,4-diacetylphloroglucinol (2,4-DAPG) and hydrogen cyanide (HCN). It also produces proteases and uncharacterized siderophores (Sid). A mutant strain SM2214, obtained by Tn5 insertion, did not produce 2,4-DAPG, HCN or proteases, but overproduced Sid. Marker-exchange mutagenesis confirmed that a single transposon insertion caused the multiple phenotypic changes of this mutant. Complementation of the mutant with a 1.3-kb DNA fragment that was amplified from genomic DNA of the wild-type P. fluorescens strain by PCR could restore the lost functions of the mutant strain. Nucleotide sequencing revealed that the fragment contained a 642-bp open reading frame (ORF) highly homologous to the regulator responser gene gacA. The in vitro anti-bacterium test and plant protection experiment under greenhouse conditions indicated that the gacA gene played an important role in the suppression of tomato bacterial wilt disease.

Field studies were conducted to determine how the spatial arrangement of weed populations influences interspecific competition. We studied the influence of regular, random, and clumped distributions of barnyardgrass on growth and yield of direct-seeded tomato planted at different densities. Increasing aggregation increased intraspecific competition in barnyardgrass. At the same time, interspecific competition experienced by tomato from barnyardgrass decreased. Differences in the amount of shading of the tomato canopy by barnyardgrass contributed to yield loss differences for the various spatial arrangements. Clumped barnyardgrass caused significantly less average shading than barnyardgrass in regular or random arrangements. At a typical planting density of 10 tomato plants m⁻⁻¹ of row, yield losses ranged from 10 to 35%% (1993) or 8 to 50%% (1994) when competing with a clumped arrangement of barnyardgrass. At the same tomato density, yields were reduced from 20 to 50%% (1993) or 11 to 75%% (1994) for the regular and random arrangements for the same barnyardgrass densities. Predicted single-season economic threshold densities for barnyardgrass at a typical tomato planting density of 10 plants m⁻⁻¹ would be one barnyardgrass plant per 25, 19, or 15 m of crop row, respectively, for regular, random, and clumped spatial distributions.Nomenclature: Barnyardgrass, Echinochloa crus-galli (L.) Beauv. ECHCG; tomato, Lycopersicon esculentum L. ‘‘Peelmech’’.

Salt stress is one of the most serious environmental factors limiting the productivity of crop plants. To understand the molecular basis for salt responses, we used mutagenesis to identify plant genes required for salt tolerance in tomato. As a result, three tomato salt-hypersensitive ( tss ) mutants were isolated. These mutants defined two loci and were caused by single recessive nuclear mutations. | This work was supported by a grant from the Universidad de Málaga and Junta de Andalucía (Grant No. AGR-168). | Peer reviewed

Starting from a population of forty isolates of endophytic bacteria obtained of healthy tomato plants, a massal screening was performed using Alternaria solani and Pseudomonas syringae pv. tomato as challenging pathogens. Based on the average number of lesions per plant and their respective standard deviations, four isolates were selected and evaluated as potential agents of biocontrol of tomato diseases caused by fungi and bacteria. The four endophytes selected for biocontrol were also evaluated for their ability to promote growth. In order to confirm the endophytic condition of the selected antagonists, isolates resistant to 1000 ppm of streptomycin sulfate were selected, introduced into healthy plants and then were detected in internal tissues of the host. | Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Tomato plants constitutively express a neutral leucine aminopeptidase (LAP-N) and an acidic LAP (LAP-A) during floral development and in leaves in response to insect infestation, wounding, and Pseudomonas syringae pv. tomato infection. To assess the physiological roles of LAP-A, a LapA-antisense construct (35S:asLapA1) was introduced into tomato. The 35S:asLapA1 plants had greatly reduced or showed undetectable levels of LAP-A and LAP-N proteins in healthy and wounded leaves and during floral development. Despite the loss of these aminopeptidases, no global changes in protein profiles were noted. The 35S:asLapA1 plants also exhibited no significant alteration in floral development and did not impact the growth and development of Manduca sexta and P. syringae pv. tomato growth rates during compatible or incompatible infections. To investigate the mechanism underlying the strong induction of LapA upon P. syringae pv. tomato infection, LapA expression was monitored after infection with coronatine-producing and -deficient P. syringae pv. tomato strains. LapA RNA and activity were detected only with the coronatine-producing P. syringae pv. tomato strain. Coronatine treatment of excised shoots caused increases in RNAs for jasmonic acid (JA)-regulated wound-response genes (LapA and pin2) but did not influence expression of a JA-regulated pathogenesis-related protein gene (PR-1). These results indicated that coronatine mimicked the wound response but was insufficient to activate JA-regulated PR genes.

Tomato yellow mosaic was first described in 1963, as a disease caused by a geminivirus transmitted by the whitefly Bemisia tabaci in Venezuela. In 1981 and 1985, Tomato yellow mosaic virus (ToYMV) was reported to occasionally infect potato plants growing in the proximity of tomato plantings affected by this virus. Despite these previous reports, a virus isolated from yellow mosaic-affected potato plants in Venezuela, was described in 1986 as a new geminivirus called potato yellow mosaic virus (PYMV). In recent years, different geminiviruses related to PYMV have been described from tomato fields in Venezuela and other countries in the Caribbean Basin, including Panama. Comparative nucleotide and amino acid sequence analyses of a 1698?bp fragment amplified from the common region and part of the AV1 and AC1 ORFs of ToYMV from Venezuela, yielded 95.7% sequence identity with the corresponding regions of PYMV. Nucleotide and amino acid sequence identities between ToYMV and PYMV, were 96.3% and 95.1% for AC1, and 95.7% and 100% for AV1, respectively. The identity of the nucleotide sequence for the common region of ToYMV and PYMV was 96.5%. Comparative sequence analyses conducted with ToYMV and other tomato begomoviruses present in the Caribbean region, showed only distant relationships. It is concluded here that PYMV is a synonym of ToYMV.

We examined the host range, the gene analysis of coat protein and the control of Tobacco mosaic virus F28 that occured necrotic fruits in gMidih-type Tomato gKoshi-no-Rubyh. TMV-F28 and TMV-OM coat protein gene have nucleotide and amino acid homologies of 98.5 and 98.8“. Out of 3 cultivar 40 plant species belonging 14 families, which were inoculated with sap of TMV-F28, 3 cultivar 21 species belonging to 7 family were infected. Host range and their symptoms were similar to TMV-OM. For rapid and convenient detection of TMV-F28,we examined the detectable condition of the modified indirect ELISA(‡T-ELIS4). TMV was specifically detected by using antigen diluted l:10000, antiserum diluted l:20,000 in the sap of tomato plant infected with ToMV, and anti-rabbit IgG alkaline phoshatase conjugate diluted l:4000. Using an Attenuated tomato mosaic virus ToMV-L sub (11) A, we investigated cross protection against TMV-F28. Pre-inoculation of Tomato plants with ToMV-L sub (11) A didnft protected from infection with TMV-F28, since it induced mosaic leaf symptoms and necrotic fruits. TMV-F28 inoculated 25 resistant cultevars, it caused systemic invasion followed by mosaic or chlorosis on cultevars containing resistance gene Tm-1. On cultevars with the resistance gene Tm-2 or Tm-2 sub (4), the virus induced necrotic local lesions on the inoculated leaves, necrosis on the upper leaves and stunt. But it was not observed symptoms by the virus on tomato cultivar gOrange-carolh with resistant geneiTm-2/+j.