Commercial Tomato Varieties Research Articles

PLANT SCIENCE: A chemical genetic roadmap to improved tomato flavor

Modern commercial tomato varieties are substantially less flavorful than heirloom varieties. To understand and ultimately correct this deficiency, we quantified flavorassociated chemicals in 398 modern, heirloom, and wild accessions. A subset of these accessions was evaluated in consumer panels, ide

Improving agronomic water use efficiency in tomato by rootstock-mediated hormonal regulation of leaf biomass

Water availability is the most important factor limiting food production, thus developing new scientific strategies to allow crops to more efficiently use water could be crucial in a world with a growing population. Tomato is a highly water consuming crop and improving its water use efficiency (WUE) implies positive economic and environmental effects. This work aimed to study and exploit root-derived hormonal traits to improve WUE in tomato by grafting on selected rootstocks. Firstly, root-related hormonal parameters associated to WUE were identified in a population of recombinant inbred lines (RILs) derived from the wild tomato species Solanum pimpinellifolium. A principal component analysis (PCA) revealed that some hormonal traits were associated with productivity (plant biomass and photosynthesis) and WUE in the RIL population. Leaf ABA concentration was associated to the first component (PC1) of the PCA, which explained a 60% of the variance in WUE, while the ethylene precursor ACC and the ratio ACC/ABA were also associated to PC1 but in the opposite direction. Secondly, we selected RILs according to their extreme biomass (high, B, low, b) and water use (high, W, low, w), and studied the differential effect of shoot and root on WUE by reciprocal grafting. In absence of any imposed stress, there were no rootstock effects on vegetative shoot growth and water relations. Finally, we exploited the previously identified root-related hormonal traits by grafting a commercial tomato variety onto the selected RILs to improve WUE. Interestingly, rootstocks that induced low biomass and water use, ‘bw’, improved fruit yield and WUE (defined as fruit yield/water use) by up to 40% compared to self-grafted plants. Although other hormonal factors appear implicated in this response, xylem ACC concentration seems an important root-derived trait that inhibits leaf growth but does not limit fruit yield. Thus tomato WUE can be improved exploiting rootstock-derived hormonal signals which control leaf growth.

Study on Agronomic Evaluation of Tomato (Lycopersicon Esculentum, Mill.) Varieties for Phonological, Growth and Yield Characters

The field experiment was carried out at the research station of Mehoni Agricultural Research Center, Fachagama, Ethiopia in 2013 and 2014 cropping season under irrigation and in 2014 for rain fed experiment only. The experiment consisted of four commercial tomato varieties arranged in a completely randomized block design with four replications. In the 2013 cropping season, days to 50% flowering and maturity, plant height, fruit length, fruit diameter, number of fruits per plant, marketable yield, unmarketable yield and total yield were significantly influenced by varietal difference. Likewise, it was also observed that variety exerted a significance effect on establishment percentage, days to 50% maturity, plant height, number of fruits/plant and marketable yield under both irrigation and rain fed and on unmarketable yield under irrigation conditions of the 2014 cropping year. Under irrigation, the highest marketable yield (414.58 q ha-1) was obtained at Chali variety followed by Miya variety (289.17 q ha-1) in 2014 while the lowest value (110.83 q ha-1) was obtained from Melka sholla in the 2013 cropping season. Whereas the highest (295.58 q ha-1) and lowest marketable yields (283.33 q ha-1) were observed at Chali and Melksa sholla varieties under rain fed condition of the 2014 cropping season.

Grafting on a Non-Transgenic Tolerant Tomato Variety Confers Resistance to the Infection of a Sw5-Breaking Strain of Tomato spotted wilt virus via RNA Silencing.

RNA silencing controls endogenous gene expression and drives defensive reactions against invasive nucleic acids like viruses. In plants, it has been demonstrated that RNA silencing can be transmitted through grafting between scions and silenced rootstocks to attenuate virus and viroid accumulation in the scions. This has been obtained mostly using transgenic plants, which may be a drawback in current agriculture. In the present study, we examined the dynamics of infection of a resistance-breaking strain of Tomato spotted wilt virus (RB-TSWV) through the graft between an old Apulian (southern Italy) tomato variety, denoted Sl-Ma, used as a rootstock and commercial tomato varieties used as scions. In tests with non-grafted plants, Sl-Ma showed resistance to the RB-TSWV infection as viral RNA accumulated at low levels and plants recovered from disease symptoms by 21 days post inoculation. The resistance trait was transmitted to the otherwise highly susceptible tomato genotypes grafted onto Sl-Ma. The results from the analysis of small RNAs hallmark genes involved in RNA silencing and virus-induced gene silencing suggest that RNA silencing is involved in the resistance showed by Sl-Ma against RB-TSWV and in scions grafted on this rootstock. The results from self-grafted susceptible tomato varieties suggest also that RNA silencing is enhanced by the graft itself. We can foresee interesting practical implications of the approach described in this paper.

Ethylene signalling affects susceptibility of tomatoes to Salmonella

Fresh fruits and vegetables are increasingly recognized as important reservoirs of human pathogens, and therefore, significant attention has been directed recently to understanding mechanisms of the interactions between plants and enterics, like Salmonella. A screen of tomato cultivars for their susceptibility to Salmonella revealed significant differences in the ability of this human pathogen to multiply within fruits; expression of the Salmonella genes (cysB, agfB, fadH) involved in the interactions with tomatoes depended on the tomato genotype and maturity stage. Proliferation of Salmonella was strongly reduced in the tomato mutants with defects in ethylene synthesis, perception and signal transduction. While mutation in the ripening-related ethylene receptor Nr resulted only in a modest reduction in Salmonella numbers within tomatoes, strong inhibition of the Salmonella proliferation was observed in rin and nor tomato mutants. RIN and NOR are regulators of ethylene synthesis and ripening. A commercial tomato variety heterozygous for rin was less susceptible to Salmonella under the greenhouse conditions but not when tested in the field over three production seasons.

Protein, free amino acid, phenolic, β-carotene, and lycopene content, and antioxidative and cancer cell inhibitory effects of 12 greenhouse-grown commercial cherry tomato varieties

The content of water, free amino acids, amino acid metabolites, crude protein, the carotene pigments β-carotene and lycopene, and 9 characterized and 2 incompletely characterized individual phenolic (flavonoid) compounds of 12 greenhouse-grown cherry tomato varieties of various colors (green, yellow, orange, red, and black) was determined using HPLC and LC/MS methods. The phenolic content of the cherry tomatoes per unit weight is 3-4 times greater than reported values for large-sized tomatoes. Antioxidative effects using the ABTS and FRAP assays and cancer-cell-inhibiting effects against 2 normal (Chang liver and Hel299 lung) and 3 human cancer (lung A549; liver HepG2; and cervical HeLa) cell lines using the MTT cell viability assay were also determined. Lycopene inhibited all the cell lines, but showed strong activity against the cervical carcinoma and the lung cancer cells. The tomato extracts showed inhibition at the higher doses. The HeLa cervical carcinoma cell line was most inhibited by the pure compounds, and the HeLa or the HepG2 cells lines were the most inhibited by the tomato extracts. The results demonstrate wide-ranging differences as well as similarities in the content of nutritional and bioactive compounds in cherry tomatoes, and suggest that such knowledge can benefit consumers.

Evaluation of Tomato Varieties under Organic Production Practices in Georgia

Tomato (Solanum lycopersicum) is a popular crop among organic growers, particularly open-pollinated varieties; however, there is a lack of information evaluating these varieties in comparison with commercial F1 hybrids. This study was undertaken to compare conventionally produced commercial F1 tomato varieties available in the southeastern United States with open-pollinated varieties popular among organic growers. Nineteen tomato varieties were evaluated in 2011 and 2012 using the U.S. Department of Agriculture National Organic Program guidelines; however, the land used had not been in 3 years of organic production. Staked tomatoes were grown on plastic mulch. Data collected included early and total graded yield. In general, F1 hybrid, determinate or semideterminate varieties, had the best early and total yields compared with open-pollinated varieties. HSX 8115H and ‘Celebrity’ had the highest early total yield. ‘Costoluto Fiorentino’, an open-pollinated variety, also had good early total yield, but significantly less than HSX 8115H or ‘Celebrity’. ‘Costoluto Fiorentino’ was the only open-pollinated variety among the five highest yielding varieties for early total yield. In addition, ‘Celebrity’ had the greatest total yield of all the entries tested. All of the top five varieties for total yield were F1 hybrids and either determinate or semideterminate types. ‘Costoluto Fiorentino’ had total yield of 22,046 lb/acre, which was 14.3% lower than the lowest yielding variety in the top five yielding varieties. ‘Florida Pink’ had the largest average fruit weight, which also had the lowest total yield of all the entries. Although the open-pollinated varieties, popular among organic and local growers, yielded less than F1 hybrids, they may possess characteristics of color, flavor, or texture that are desired and were not evaluated in this study. This may be an opportunity for plant breeders to develop varieties desired by local organic growers that have unique characteristics, in addition to high yields and disease resistance.

Visible reflectance and content of isomeric ratio of lycopene in commercial and elevated lycopene tomato varieties by different technological traits

Quantification of red pigment content of fruits using destructive techniques is expensive and it enables only the analysis of batches but not of individual items. This study examined the feasibility of using non-destructive, spectrophotometric method to predict one of the most valuable internal quality indices, lycopene, in individual tomato fruits. An open field experiment was conducted to study the effect of irrigation and potassium supplementation on the yield and lycopene content of processed tomato fruit. Three different treatments (regularly irrigated RI, irrigation cut-off 30 days before harvest CO, and rainfed RF unirrigated control) and two different potassium fertilisations (P) were applied. Regular irrigation significantly decreased the lycopene content of tomato fruits. The CO treatment resulted in the highest total lycopene without potassium supplementation. Potassium supplementation, given at the time before fruit maturity, significantly increased the lycopene concentration of cultivar Briga...

Bacterial community compositions of tomato (Lycopersicum esculentum Mill.) seeds and plant growth promoting activity of ACC deaminase producing Bacillus subtilis (HYT-12-1) on tomato seedlings

Study of endophytic bacteria within plant seeds is very essential and meaningful on account of their heritability and versatility. This study investigated Bacillus bacterial communities within the seeds of four commercial tomato varieties, by 16S rRNA gene PCR-RFLP (restriction fragment length polymorphism). Phylogenetic analysis of 16S rRNA gene sequences indicated that the 22 representative isolates belonged to five species of genus Bacillus and the bacterial compositions showed remarkable differences among tomato varieties. Isolates exhibited multiple plant growth promoting (PGP) traits: 37 % of indole-3-acetic acid production; 37 % of phosphate solubilization; 24 % of siderophores production; 85 % of potential nitrogen fixation and 6 % of 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Isolate HYT-12-1 was shown to have highest ACC deaminase activity (112.02 nmol α-ketobutyrate mg⁻¹ protein h⁻¹) among the five ACC deamiase producing strains. 16S rRNA gene sequencing indicated that the isolate HYT-12-1 shared the highest sequence similarity (100 %) with B. subtilis. PGP experiments under gnotobiotic and greenhouse conditions revealed the ability of strain HYT-12-1 to enhance the growth of tomato seedlings. This is the first study to describe endophytic Bacillus communities within tomato seeds, and the results suggest that B. subtilis strain HYT-12-1 would have a great potential for industrial application as biofertilizer in the future.

Indications of variation in host suitability to root-knot nematode populations in commercial tomato varieties

The host suitability of 21 local, commercial tomato varieties were evaluated in concurrent greenhouse trials for resistance to Meloidogyne incognita race 2 and Meloidogyne javanica, respectively. M. incognita race-2-resistance identified in variety ‘Rhapsody’ during the latter study was subsequently verified in a follow-up microplot trial using differential initial population (Pi) densities and as well as in a field trial with four soil amendments. Substantial variation existed among the tomato varieties in the greenhouse screening with regard to resistance to the respective root-knot nematode species. Comparison of the different indicators of resistance used for the two species showed that labelling of specific varieties as resistant should not only be based on one criterium, since it could be insufficient. Strong non-linear relationships were shown in the microplot trial between Pi and Pf in the roots of both tomato varieties but nematode reproduction was poor on the resistant ‘Rhapsody’. Significantly lower Pf in roots and J2 in soil was obtained for ‘Rhapsody’ compared to the susceptible Moneymaker. In the soil-amendment field trial, ‘Rhapsody’ also maintained significantly lower M. incognita numbers compared to ‘Moneymaker’ in all treatments. These results confirm the superior resistance of ‘Rhapsody’ to local M. incognita race-2 populations used in this study. More frequent and extensive screenings of commercial tomato material are recommended in order to provide resource-poor producers with better options for improved and sustainable yields.

Field Testing of Tomato Chilling Tolerance under Varying Light and Temperature Conditions

Chilling tolerance is a desirable trait in commercial tomato varieties, in order to extend the growing season and geographic range. Two Nearly Isogenic Lines (NILs) with introgressions in chromosome 2 and 3 of Solanum habrochaites S. Knapp & D.M. Spooner, a cold-resistant wild tomato, were evaluated in the field. Four plantings were established between 21 August and 2 October 2006 (day 232 and 274). Throughout the experiment the heat sum was interpreted using air temperature to calculate growing degree days (base 12 °C) and chilling hours (below 12 °C), with the daily light integral calculated as global solar radiation. The relative post-transplant growth rate, fruit set and yield, were evaluated over two successive 10-d periods. Chilling tolerance is expressed under high radiation and low temperature conditions, which occurred during the 10-d post-transplant evaluation period beginning on day 257, when both NILs achieved a leaf area growth rate 1.7 times higher than the control plants. During the second evaluation period, 10-20 d post-transplant, both NILs grew on average, 1.4 times more than the control. There were no significant differences in earliness or fruit set. These NILs should not be used as a direct source to obtain chilling tolerant varieties, because of the low fruit set, 84% lower in LA3921 than the control, probably due to linkage drag and poor environmental adaptability in both lines.

Development of regeneration system and study of the transformation potential of a commercial tomato variety

The regeneration and transformation potentials of tomato variety Rekordsmen having economically valuable traits is studied. The optimal hormonal composition of the nutrient medium and type of explant for producing the greatest number of shoots are determined. The efficiency of introducing the gfp gene during Agrobacterium transformation is estimated.

Genetic analysis of physiological components of salt tolerance conferred by Solanum rootstocks. What is the rootstock doing for the scion?

Grafting desirable crop varieties on stress-tolerant rootstocks provides an opportunity to increase crop salt tolerance. Here, a commercial hybrid tomato variety was grafted on two populations of recombinant inbred lines developed from a salt-sensitive genotype of Solanum lycopersicum var. cerasiforme, as female parent, and two salt-tolerant lines, as male parents, from S. pimpinellifolium, the P population, and S. cheesmaniae, the C population, to identify an easy screening method for identifying rootstocks conferring salt tolerance in terms of fruit yield. Potential physiological components of salt tolerance were assessed in the scion: leaf biomass, [Na(+)], nutrition, water relations and xylem ABA concentration. A significant correlation between scion fruit yield and scion leaf fresh weight, water potential or the ABA concentration was found in the C population under salinity, but the only detected QTL did not support this relationship. The rootstocks of the P population clearly affected seven traits related to the sodium, phosphorous and copper concentrations and water content of the scion leaf, showing heritability estimates around 0.4 or higher. According to heritability estimates in the P population, up to five QTLs were detected per trait. QTLs contributing over 15% to the total variance were found for P and Cu concentrations and water content of the scion leaf, and the proportion of fresh root weight. Correlation and QTL analysis suggests that rootstock-mediated improvement of fruit yield in the P population under salinity is mainly explained by the rootstock's ability to minimise perturbations in scion water status.

Effect of variety and grafting on lycopene content of tomato (Lycopersicon lycopersicumL. Karsten) fruit

Lycopene, found primarily in tomatoes, is a member of the carotenoid family and has potent antioxidant capability. The aims of the present study were: 1) to investigate the effect of grafting on lycopene content of tomatoes and 2) to evaluate the effects of different varieties on lycopene content (open-field with supporting-system, open-field with processing varieties) under the same ecological conditions. The effect of grafting on lycopene content was analysed in the case of two varieties, between the years 2001 and 2003. Lycopene content of tomato fruits decreased significantly by grafting. Ten commercial varieties of tomato produced in Hungary were examined for their lycopene content. Lycopene content of tomato turned out to be extremely diverse, and variable (63.0–155.0 mg/kg fresh weight). It was found that the variety of tomato is one of the most important determinants of lycopene content.

Assessment of genetic variation among commercial tomato (Solanum lycopersicum L) varieties using SSR markers and morphological characteristics

Simple sequence repeats (SSR) is one of the most suitable markers for variety identification as it has great discrimination power for varieties with limited genetic variation. Genetic characterization of commercial tomato varieties was investigated using 33 SSR markers and 22 morphological traits. Thirty three SSR primer pairs were screened for 63 tomato varieties. A total of 132 polymorphic amplified fragments were obtained by using 33 SSR markers. The average polymorphism information content (PIC) was 0.628 ranging from 0.210 to 0.880. One hundred thirty two SSR loci were used to calculate Jaccard's distance coefficients for UPGMA cluster analysis. A clustering group of varieties, based on the results of SSR analysis, were categorized into cherry and classic fruit type varieties. Almost all of the varieties were discriminated by SSR marker genotypes. The relationship between morphological and molecular data for 33 varieties out of 63 varieties was analyzed using Mantel matrix correspondence test. The correlation value between two methods was 0.644. However, SSR based dendrogram topology showed some similar form with morphological traits at the two main groups. Therefore, these markers may be used wide range of practical application in variety identification and pre-screening for distinctiveness test of tomato varieties.

Effect of Mi-1.2 gene in Natal Host Plants on Behavior and Biology of the Tomato Psyllid Bactericerca cockerelli (Sulc) (Hemiptera: Psyllidae)

The Mi-1.2 gene has been isolated from wild varieties of tomato, Solanum peruvianum (Mill), and incorporated into near isogenic commercial varieties of tomato, Solanum lycopersicon. Plants containing the gene confer resistance to tomato psyllid, Bactericerca cockerelli (Sulc), as well as species of aphids, whiteflies, and nematodes. Considering bias in host preference and oviposition responses based on early adult experience is well documented in the literature; the objective of this study was to determine if the presence or absence of the Mi-1.2 in the rearing host influenced subsequent host selection, oviposition, and development time. The results presented here show that the host that psyllids developed on did not affect subsequent selection of host for oviposition, but incidence of oviposition was higher on plants that did not contain the Mi-1.2 gene [Moneymaker (mi-1.2)] compared to plants with the Mi-1.2 gene [Motelle (Mi-1.2)]. Psyllid nymph survival and development time did not differ between plant varieties. Consequently, plants containing the gene may be useful components to IPM programs to control the tomato psyllid.

A new approach for in vitro regeneration of tomato plants devoid of exogenous plant growth hormones

Many available methodologies for in vitro regeneration of commercial tomato varieties promote not only the production of normal shoots but also individual leaves, shoots without apical meristems and vitrified structures. All these abnormal formations influence and diminish the regeneration efficiency. At the basis of this phenomenon lies callus development. We optimized an alternative procedure by which the regeneration occurs without abnormal shoot formation. The portion including the proximal part of hypocotyls and the radicle was cultured on medium consisting of Murashige and Skoog salts, 4 mg/L thiamine, 100 mg/L mio-inositol and 3% sucrose. After two-three weeks, 60% explants showed adventitious shoot formation. No changes in the morphological characteristics of regenerated plants and fruits were observed as compared with parents. Karyotypic analysis of regenerated plants showed no variations in chromosome number. The optimized procedure offers the advantage of tomato plant regeneration avoiding callus formation, which enables normal plant recovery with an efficiency ranging from 1.45 +/- 0.05 to 2.57 +/- 0.06 shoots per explant in Campbell-28, Amalia, Lignon, and Floradel cultivars.

Behavior and biology of the tomato psyllid, Bactericerca cockerelli, in response to the Mi‐1.2 gene

AbstractThe Mi‐1.2 gene, identified from wild varieties of tomato, Solanum peruvianum (Mill) (Solanaceae), has been incorporated into near‐isogenic commercial varieties of tomato and has been shown to confer resistance to three different species of phloem feeders: aphids, whiteflies, and nematodes. The results presented here show that plants bearing Mi‐1.2 were also resistant to the tomato psyllid, Bactericerca [Paratrioza] cockerelli (Sulc) (Homoptera: Psyllidae), a serious pest of tomato, Solanum lycopersicon (Mill), in the western half of North America. In choice studies, tomato psyllids preferred to settle on plants that did not contain the gene [Moneymaker (mi‐1.2)] compared to near‐isogenic plants with the gene [Motelle (Mi‐1.2)]. As a result, total oviposition was higher on the susceptible variety, although no‐choice studies indicated that there were no differences in numbers of eggs laid by individual females on either variety. Survival from egg to adult was higher on plants lacking the gene compared to plants containing the gene. However, there were no differences in total development time of individuals reared from either variety. The results suggest that mechanisms of resistance to the tomato psyllid observed in plants bearing the Mi‐1.2 gene are distinct from the mechanisms of resistance to the three phloem feeders examined in other studies.

INFLUENCE OF HARVEST DATE ON FRUIT TECHNOLOGICAL TRAITS OF FIVE PROCESSING TOMATO VARIETIES

Tomato (Lycopersicon esculentum MILL) is an important crop cultivated in Hungary. Tomatoes are composed primarily of water (93-96%), but they are also an important source of lycopene, vitamins, carbohydrates and minerals. Lycopene is a carotenoid found primarily in tomatoes. In this study were investigated the influence of two harvest dates on the technological traits, percent soluble solids (Brix°) composition parameters (lycopene, carbohydrates, organic acid and vitamin C content) of five well-known commercial processing tomato varieties. The results showed that (1) lycopene content ranged from 60.8 to 171.0 mg/kg, two varieties stood out with particularly high values with especial regard to second harvest date. (2) Carbohydrates constitute nearly 50% of the fruit dry matter. (3) It was found significant difference among varieties and between harvest dates in terms of lycopene, vitamin C and organic acid content.

COMPARATIVE STUDY OF THE PIGMENT CONTENT OF DIFFERENT CROP CYCLE TOMATO VARIETIES FOR INDUSTRY

06008 Badajoz. Spain The tomato fruit colour should be a full red of both flesh and skin. This quality attribute is that which the consumer perceives first, and determines other quality factors, such as flavour and aroma. The characteristic red colour of tomato is given by a combination of carotenoid pigments of which the most abundant is lycopene. These carotenoid functions are under intensive investigation by several research teams, and scientific data, on anti-oxidative and anti-cancer properties amongst others, have been published nowadays. The main dietary human source of lycopene is the ripe red tomato. A study was carried out to analyse the influence of crop cycle on the agronomic and physical-chemical parameters of several well-known commercial tomato varieties, focus on colour and pigments content (carotenoids, lycopene (cis-lycopene, lycopene epoxide, all trans lycopene), luthein, and all-trans- β-carotene and cis-β-carotene). A total of 3 varieties with 3 different samples and 5 replications each belonging to the three classical periods of the season were evaluated during summer 2.001. The study was carried out throughout the raw tomatoes varieties to discover possible differences between varieties and to characterise these by their carotenoid pattern and content for selecting the best varieties.