Unripe Tomatoes Research Articles

Oviposition preference in the oligophagous tomato fruit fly, Neoceratitis cyanescens

AbstractWe assessed the role of visual and olfactory cues on oviposition preference in the oligophagous tomato fruit fly, Neoceratitis cyanescens (Bezzi) (Diptera: Tephritidae). In a field survey, we evaluated the stage of susceptibility of field‐grown tomatoes by monitoring N. cyanescens infestations from fruit‐setting up to harvest, in relation to post‐flowering time, size, and visual properties of fruit. In two‐choice laboratory experiments, we tested the degree to which females use visual and olfactory cues to select their host plant for oviposition. In addition, we investigated the ability of flies to avoid fruit already infested by conspecific eggs or larvae, and the influence of natal host fruit on oviposition preference. Neoceratitis cyanescens females preferentially lay their eggs in small yellow‐green unripe fruit (2–3.5 cm diameter, 10–21 days post‐flowering). Damage to fruit was significantly affected by brightness and size properties. In laboratory experiments, females chose to lay their eggs in bright orange rather than yellow domes. On the sole basis of olfactory stimuli, females showed a significant preference for unripe vs. ripe host fruit, for unripe fruit vs. flowers or leaves, and for host vs. non‐host fruit (or control). However, colour interacted with odour as females dispatched their eggs equally between the yellow dome and the bright orange dome when unripe fruit of tomato was placed under the yellow dome vs. ripe fruit under the bright orange dome. When offered real ripe and unripe tomatoes, females preferred unripe tomatoes. Females significantly chose to lay eggs in non‐infested fruit when they were given the choice between these or fruit infested with larvae. In contrast, recent stings containing eggs did not deter females from laying eggs. Rather, they could have an attractive effect when deposited within <1 h. Regardless of their natal host plant, tomato or bugweed, N. cyanescens females laid significantly more eggs in a dome containing bugweed fruit. However, 15% of females originating from tomato laid eggs exclusively in the dome with tomato, against 3% of females originating from bugweed.

Chemical analysis of a polysaccharide of unripe (green) tomato ( Lycopersicon esculentum)

A polysaccharide (PS-I) isolated from the aqueous extract of the unripe (green) tomatoes ( Lycopersicon esculentum) consists of d-galactose, d-methyl galacturonate, d-arabinose, l-arabinose, and l-rhamnose. Structural investigation of the polysaccharide was carried out using total acid hydrolysis, methylation analysis, periodate oxidation study, and NMR studies ( 1H, 13C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of above-mentioned experiments the structure of the repeating unit of the polysaccharide (PS-I) was established as: ▪

Metabolite profiling of tomato (Lycopersicon esculentum) using 1H NMR spectroscopy as a tool to detect potential unintended effects following a genetic modification.

The maize transcription factors LC and C1 were simultaneously overexpressed in tomato with the aim of producing lines with increased amounts of flavonols. The metabolite composition of these genetically modified tomatoes has been compared with that of azygous (nonmodified) controls grown side-by-side under the same conditions. It has been possible to observe metabolic changes in both types at different stages of maturity. (1)H NMR spectra showed that the levels of glutamic acid, fructose, and some nucleosides and nucleotides gradually increase from the immature to the ripe stage, whereas some amino acids such as valine and gamma-aminobutyric acid were present in higher amounts in unripe tomatoes. Apart from the significantly increased content of six main flavonoid glycosides (mainly kaempferol-3-O-rutinoside, with additional increases in kaempferol-3,7-di-O-glucoside (1), kaempferol-3-O-rutinoside-7-O-glucoside (2), kaempferol-3-O-glucoside, a dihydrokaempferol-O-hexoside (3), and naringenin-7-O-glucoside), the levels of at least 15 other metabolites were found to be different between the two types of red tomato. Among them were citric acid, sucrose, phenylalanine, and trigonelline. However, although statistically significant, these changes in mean values were relatively minor (less than 3-fold) and within the natural variation that would be observed in a field-grown crop. Nevertheless, this study clearly showed that NMR combined with chemometrics and univariate statistics can successfully trace even small differences in metabolite levels between plants and therefore represents a powerful tool to detect potential unintended effects in genetically modified crops.

Searching for the semantic boundaries of the Japanese colour term‘AO’

The Japanese language has a colour term,‘ao’, which is usually referred to in bilingual dictionaries as being the equivalent of English ‘blue’. Very often, however, it is used to describe things which English speakers would describe as being green. Granny Smith apples are‘ao’, so are all Westerners ‘ eyes, regardless of whether they would be described as being ‘blue’ or ‘green’ in English. The sky and the sea are prototypically‘ao’, but this term is also used to describe lawns, forests, traffic lights and unripe tomatoes. What, then, do Japanese native speakers (JNS) understand by this term? How do its semantic boundaries relate to those of the term‘midori’(‘green’)? What is the JNS understanding of the foreign loan words ‘guriiri (green) and‘buruu’(blue)? This paper reports on‘ao’prototypes and prototype theory’s good and bad examples of referents for these four colour terms. It explores, from a semasiological perspective, both the relationships of entailment and the processes of exclusion which operate when JNS select amongst these colour terms. The possibilities and non-possibilities for the shared use of these colour terms are identified for a variety of referents.

AE—Automation and Emerging Technologies: Multi-spectral Prediction of Unripe Tomatoes

The consumer at the retail outlet rejects tomatoes harvested before reaching physiological ripeness, as the produce does not ripen properly. Although many packing houses have inserted vision systems for tomato sorting and sizing, it is impossible to distinguish between fruits that will ripen and fruits that will not at the harvest day, as all the fruits are green. A tomato maturity predictive sensor was developed to be used at packing houses for detecting unripe tomatoes that will never turn red. Spectral and colour measurements were taken from green-mature tomatoes just after harvest. Colour was measured daily and used as an index for classifying first-day spectral data into ripe or unripe. The groups were analysed by discriminant analysis in order to obtain the best discriminant wavelengths. Those spectral bands were used by a multi-spectral imager for predicting those tomatoes that will never ripen with an accuracy of over 85%.

Applied studies of plant meridian system: I. The effect of agri-wave technology on yield and quality of tomato.

Agri-wave technology is a new agricultural technology based on the plant meridian system, that focuses on measurement of plant sound characteristics. The basic principle of agri-wave technology is to improve the yield and quality of plants such as vegetables, flowers, and fruit trees by broadcasting sound waves of certain frequencies and spraying a compound microelement fertilizer on the leaves. The application of agri-wave technology on tomatoes remarkably stimulates growth of their seedlings. Fresh weight of the branch, stems, and leaves of the treated tomatoes is significantly (59.53%, P < 0.0001) higher than that of the control group. Sampling survey results indicate that agri-wave technology accelerates the ripeness of tomatoes. The fresh weight of ripe tomatoes treated with this technique is 30.73% higher than that of the untreated (P = 0.0018), while the fresh weight of the treated unripe tomatoes is 27.29% lower than that of the untreated unripe group (P = 0.0020). Yield surveys show that the yield of treated plants is 13.89% (p < 0.0001) higher than that of the control group. Moreover, with agri-wave technology treatment the storage period of tomatoes is almost doubled. Analysis of tomato nutrition shows that agri-wave technology has increased their sugar content by 26.19%, vitamin A and niacin (an antifavours vitamin) by 55.39% and 92.31% respectively. There is no difference concerning vitamin B1, B2, and D content between the two groups, and vitamin C and E contents decreased by 2.10% and 12.69%, respectively. Among the analyzed 33 minerals of tomatoes, 26 increased in content, while 7 decreased. In conclusion, agri-wave technology has promoted the growth of the tomato, increased its yield, and improved its quality.

Phase Separation of Plant Cell Wall Polysaccharides and Its Implications for Cell Wall Assembly

Concentrated binary mixtures of polymers in solution commonly exhibit immiscibility, resolving into two separate phases each of which is enriched in one polymer. The plant cell wall is a concentrated polymer assembly, and phase separation of the constituent polymers could make an important contribution to its structural organization and functional properties. However, to our knowledge, there have been no published reports of the phase behavior of cell wall polymers, and this phenomenon is not included in current cell wall models. We fractionated cell walls purified from the pericarp of unripe tomatoes (Lycopersicon esculentum) by extraction with cyclohexane diamine tetraacetic acid (CDTA), Na2CO3, and KOH and examined the behavior of concentrated mixtures. Several different combinations of fractions exhibited phase separation. Analysis of coexisting phases demonstrated the immiscibility of the esterified, relatively unbranched pectic polysaccharide extracted by CDTA and a highly branched, de-esterified pectic polysaccharide present in the 0.5 N KOH extract. Some evidence for phase separation of the CDTA extract and hemicellulosic polymers was also found. We believe that phase separation is likely to be a factor in the assembly of pectic polysaccharides in the cell wall and could, for example, provide the basis for explaining the formation of the middle lamella.

The tomato polygalacturonase gene and ripening-specific expression in transgenic plants

Polygalacturonase (PG) is the major cell wall degrading enzyme of tomato fruit. It is developmentally regulated and is synthesised de novo in ripening fruit. Genomic clones encoding a PG gene of tomato (Lycopersicon esculentum Mill cv. Ailsa Craig) have been isolated, mapped and sequenced. The sequence of the protein-coding region is identical to that of a PG cDNA [20]. Comparison of the cloned restriction fragments with genomic Southern data suggests that there may only be one gene for PG per haploid genome. The PG gene, which covers approximately 7 kb, is interrupted by 8 intervening sequences ranging in size from 99 bp to 953 bp. The transcription start point was identified by S1 mapping and primer extension analysis. About 1.4 kb of 5' flanking DNA has been sequenced. This contains putative TATA and CAAT boxes and also direct repeat sequences. A transcriptional fusion has been constructed between the putative 1.4 kb promoter fragment and the chloramphenicol acetyl transferase (CAT) gene. Constructs containing this gene have been transferred to tomato using binary vectors. Regenerated transgenic plants express CAT in ripe tomato fruit, but not in unripe tomatoes, leaves, or roots.

Low-temperature injury and the storage of ripening tomatoes

SummaryTomato fruits, cv Sonatine, at the green-orange stage of ripening were held at a series of time/temperature combinations to find ways to slow down development without diminishing the quality of the fully-ripe product. Firmness, colour and appearance were measured in an assessment of fruit response. About 9°C was the minimum that would allow almost all the fruit to ripen uniformly. At lower temperatures increasingly severe damage was caused. Various types of chilling damage and details of typical conditions that cause each of them are described. A number of storage regimes involving modified atmospheres were tested to find one that protected unripe fruit from low-temperature injury. The most satisfactory system was to overwrap with PVC ‘Clingwrap’ film. Guidelines for storing unripe tomatoes for short periods without eroding the quality of the ripened product are put forward.