RIPENING INHIBITOR Research Articles

Expression of a truncated ripening inhibitor (RIN) protein from tomato and production of an anti-RIN antibody

The tomato ripening mutant, ripening inhibitor (rin), whose fruits fails to ripen, has been identified and widely studied. The RIN gene has been cloned. Here we present the expression of a truncated form of the RIN protein from tomato and the preparation of a polyclonal antibody against it. The resulting antibody recognized the RIN of crude protein extracts from different tomato tissues. The protein level of RIN in tomato was detected with this antibody by western blot, which suggested the accumulation of RIN protein increased gradually during tomato fruit ripening.

Fruit ripening mutants yield insights into ripening control

Fruit ripening is a developmental process that is exclusive to plants whereby mature seed-bearing organs undergo physiological and metabolic changes that promote seed dispersal. Molecular investigations into ripening control mechanisms have been aided by the recent cloning of tomato ripening genes that were previously known only through mutation. Advances in the genomics of tomato have provided genetic and molecular tools that have facilitated the positional and candidate-gene-based cloning of several key ripening genes. These discoveries have created new inroads into understanding of the primary ripening control mechanisms, including transcription factors such as those encoded by the RIPENING-INHIBITOR (RIN) MADS-box and COLOURLESS NON-RIPENING (CNR) SPB-box genes, which are necessary for the progression of virtually all ripening processes. They have also facilitated the elucidation of downstream signal transduction components that impact the hormonal and environmental stimuli that coordinate and modulate ripening phenotypes.

'Mountain Crest' Hybrid Tomato and its Parent, NC 1 rinEC

c) gene, extended shelf life, vine-ripe harvest ‘Mountain Crest’ is a fresh-market tomato (Lycopersicon esculentum Mill.) hybrid with extended shelf life resulting from the ripening inhibitor gene (rin) in heterozygous condition. Origin ‘Mountain Crest’, the F 1 hybrid of NC 84173PVP × NC 1 rinEC, resulted from a breeding program to develop an extendedshelf-life tomato cultivar adapted to vine-ripe production in North Carolina. Cultivars with extended shelf life based on use of the recessive ripening inhibitor gene (rin) are now widely used for vine-ripe harvest in production areas outside the U.S. The rin gene in homozygous condition eliminates the production of ethylene in tomatoes thus inhibiting ripening of fruit. When used in the heterozygous condition in fi rm-fruited backgrounds, rin slows fruit ripening and softening resulting in extended shelf life. Rin extended-shelf-life hybrids are grown for vine-ripe harvest in Mexico during the winter for export to the U.S. and have competed strongly with Florida for markets. Florida ships primarily mature green harvested fruit subjected to ethylene to stimulate ripening. Although North Carolina growers have cultivars with adequate shelf life well adapted to vine-ripe production, some retail handlers of

Ethanol vapor prior to processing extends fresh-cut mango storage by decreasing spoilage, but does not always delay ripening

This study was undertaken to optimize ethanol vapor application as a ripening inhibitor on whole mangoes to extend fresh-cut mango shelf life. Freshly harvested mangoes were first subjected to hot water (+HW) at 46 °C for 60 or 90 min to simulate quarantine heat treatments, or remained untreated (−HW). Fruit of each batch (+ or −HW) were then held at 20–25 °C for 4 or 7 d (D4 and D7) after the hot water treatment before being exposed to ethanol vapors [0 h (E0), 10 h (E10), or 20 h (E20)]. Fruit were then peeled and cut into slices, packed in plastic clamshells, and stored at 7 °C for 15 d. Only slices from +HW-D4-E20-treated fruit maintained higher firmness, hue angle, and titratable acidity (TA) in storage. The +HW-D7-E10- or E20-treated fruit had higher hue angle than E0, but firmness, total soluble solids, TA, pH, and respiration rate did not differ. Internal ethanol and acetaldehyde were very high in slices from +HW, D4 and D7, E20 and −HW-D7-E20-treated fruit. A sensory panel could perceive higher firmness and acidity in slices from fruit treated with ethanol. However, E20 induced off-flavor, and these fruit were least preferred. Ethanol exposure on fruit was repeated with purchased mangoes that had been subjected to a commercial quarantine heat treatment. A second heat treatment of 18 h at 38 °C and 98% relative humidity was added to one batch of fruit in this experiment. Ethanol vapors did not result in delayed ripening in those mangoes. However, this treatment inhibited microbial growth. The second heat treatment did not improve fresh-cut mango shelf life, and further, microbial growth increased compared to other treatments. It is concluded that, due to inconsistent results, ethanol vapor applied for 20 h to whole mangoes prior to processing for fresh-cut is not a practical approach to delay ripening; however, at lower doses (10 h), it could be used as a safe microbial control in a fresh-cut production sanitation system.

Senescence of rin, rin/rin, rin/+ and +/+ tomato fruits

Ripening inhibitor (rin) gene is a spontaneous recessive mutant which changes fruit ripening aspects (most important synthesis of carotene, especially lycopene). It also delays fruit senescence. Tomato is a vegetable crop with specific maturing climax (pik). Tomato genotypes homozygote for rin gene does not have this maturing climax, so the ethyl-ene production and red, lycopene colour does not appear. In order to research the maturing process material from the final tomato selection cycle we used: pure line S-49 (genetic constitution u/u, with uniform ripening), line hom 4 (rin/rin, homozygote with ripening inhibitor) and hybrid combination 449 Fl (u/rin, heterozygote for ripening inhibitor). Fruits with uniform ripening and hybrids ripened simultaneously, while homozygote with rin gene did not ripe at all. Ethylene stimulates the appearance of yellow colour in rin fruits and the lycopene production. After treatment with ETEPHONE (0.1%) (Ethylene) fruits with uniform ripening, senescence more quickly, while hybrids senescence slowly. Rin homozygotes did not change colors, but the fruits senescence more quickly comparing to control. Ethylene treatment speeded the maturing and senescence process in tomato fruits. Extended maturing process as a result influence of rin gene, makes the new created hybrids a late maturing ones. On the other hand, the firmness of fruits is improved as well as the "shelf life", which enables longer transportation and storing, coordinated maturing according to market demands. The aim was to research the maturing according to market demands. The aim was to research the maturing process of rin heteroyzgote, and the reaction of some genotypes to treatment with RT-REL (Ethzlene) in order to decrease extremely late maturing.

1-Methylcyclopropene influx and efflux in ‘Cox’ apple and ‘Hass’ avocado fruit

Ethylene initiates and/or co-ordinates ripening associated processes in climacteric fruits. Among climacteric fruits, avocado is relatively high in lipid content and apple is comparatively low. The ethylene binding site blocker 1-methylcyclopropene (1-MCP) was sorbed faster and in greater amounts by avocado fruit (Persea americana Mill. 'Hass') and avocado oil than by apple fruit (Malus sylvestris var. domestica, 'Cox') and water, respectively. The ability of produce to sorb 1-MCP may have an influence on 1-MCP efficacy as a ripening inhibitor and should also be considered when prescribing commercial 1-MCP application strategies. (C) 2003 Elsevier Science B.V. All rights reserved.

Ostwald Ripening of Oil-in-Water Emulsions Stabilized by Phenoxy-Substituted Dextrans

The stability of oil-in-water emulsions prepared using dextran, a natural polysaccharide, hydrophobically substituted with phenoxy groups, was studied. The evolution of the emulsion droplet size was investigated as a function of polymer concentration (Cp=0.2 to 1% w/w in a water phase) and the degree of phenoxy substitution (τ=4.2 to 15.7%). For the highest τ values, emulsions, which presented submicrometer droplets, were stable over more than 4 months at room temperature. The most substituted polymers clearly showed a better efficiency to lower the surface tension at the oil/water interface. DexP did not induce real viscosification of the continuous phase. The linearity of the particle volume variation with time, and the invariability of the volume distribution function, proved that Ostwald ripening was the main destabilization mechanism of the phenoxy dextran emulsions. The nature of the oil dispersed phase drastically affected the behavior of emulsions. While the emulsions prepared with n-dodecane presented a particle growth with time, only few size variations occurred when n-hexadecane was used. Furthermore, small ratios of n-hexadecane in n-dodecane phase reduced the particle growth due to the lower solubility and lower diffusion coefficient in water of n-hexadecane, which acted as a ripening inhibitor.

Organization and expression of polygalacturonase and other ripening related genes in Ailsa Craig ?Neverripe? and ?Ripening inhibitor? tomato mutants

The organization and expression of ripening-related genes were investigated in normal tomato (Lycopersicon esculentum cv. Ailsa Craig) and in Neverripe (Nr) and Ripening inhibitor (rin) mutants.Hybridization studies with ripening-related cDNA clones showed that the gene for polygalacturonase (PG) is barely expressed in rin and expressed at a low level in Nr fruit. Four other genes were found to be expressed at reduced levels in rin. Exogenous ethylene was able to restore higher levels of expression of all the genes showing reduced expression in rin except that for PG. However, exogenous ethylene did not restore normal ripening in rin fruit. Analysis of chromosomal DNA by Southern blotting indicated that all the genes studied, including the PG gene, and also an upstream promoter of the PG gene, are present in the rin and Nr genomes and appear to be arranged in a similar way to those in normal tomatoes. The results are discussed in the light of the suggestion that these mutations may involve part of the regulatory apparatus leading to the expression of ripening genes such as PG.

Protein differences between fruits of rin, a non-ripening tomato mutant, and a normal variety

Fruit extracts of non-ripening tomato Lycopersicon esculentum Mill strain rin contain extra protein band comparing with the normal ripening cultivar Rutgers. Another band exists in both varieties, but disappears in Rutgers at the onset of ripening. The existence of a proteinaceous ripening inhibitor is suggested.

Internal Ethylene Concentrations in Apple Fruits Attached to or Detached from the Tree1

Abstract A method is described for the measurement of internal ethylene concentration in fruits on the tree. Ethylene levels in ‘Red Delicious’ fruits immediately after harvest were similar to those in fruits on the tree during development and ripening. The levels varied mostly between 0.02 to 0.15 ppm during the period from 83 to 140 days from bloom and sharply increased from 10 to 1000-fold within 5 days as autocatalytic ethylene production began. Ripening followed the upsurge in ethylene production. Isolating fruit from leaves by girdling plus defoliation of spur leaves hastened the increase in internal ethylene by approximately 1 month. Girdling or defoliating the spur did not markedly alter the onset of autocatalytic ethylene production compared to that observed by fruits on normal spurs. The data support the concept that fruits receive a ripening inhibitor from the leaves.