Immature Green Fruit Research Articles

Molecular cloning of tomato fruit polygalacturonase: Analysis of polygalacturonase mRNA levels during ripening

The expression of a gene encoding the cell wall-degrading enzyme polygalacturonase [poly(1,4-alpha-D-galacturonide) glucanohydrolase, EC 3.2.1.15] was characterized during tomato fruit ripening. Polygalacturonase was purified from ripe tomato fruit and used to produce highly specific antiserum. Immunoblot analyses detected a 45- and a 46-kDa protein in ripe fruit but immunoprecipitation of in vitro translation products of mRNA from ripe tomato fruit yielded a single 54-kDa polypeptide, suggesting post-translational processing. A plasmid cDNA library was prepared from poly(A)(+) RNA isolated from ripe tomato fruit. The cDNA library was inserted into a lambda-based expression vector, and polygalacturonase cDNA clones were identified by immunological screening. Hybrid-select translation experiments indicated that the cDNAs encode a 54-kDa in vitro translation product that is specifically immunoprecipitated with polygalacturonase antiserum. RNA-blot analysis indicated that the 1.9-kilobase polygalacturonase mRNA was virtually absent from immature-green fruit, accumulated steadily during the ripening process, and was at its highest level in red-ripe fruit. There was at least a 2000-fold increase in the level of polygalacturonase mRNA between immature-green and red-ripe tomato fruit. These studies show that the levels of polygalacturonase mRNA are developmentally regulated during tomato fruit ripening.

Biodegradation of caffeine: Formation of theophylline and theobromine from caffeine in mature Coffea arabica fruits

AbstractThe level of theophylline in mature and ripened fruit is 20–50 times that in the immature green fruit of Coffea arabica L. Biodegradation of caffeine occurs in the mature, ripened coffee fruits through theophylline and theobromine as the first biodegradation products. It is now clear that theophylline is associated primarily with caffeine biodegradation, whereas theobromine is involved in both biosynthesis and biodegradation of caffeine.

Polyuronide Degradation and Hemicellulose Modifications in Ripening Tomato Fruit

Abstract Hemicelluloses and polyuronides from the cell wall of ripening tomato (Lycopersicon esculentum Mill. cv. Rutgers) fruit were examined using gel-filtration chromatography. Gel filtration of polyuronides revealed that these polymers were extensively degraded during ripening, as evidenced by the increase in the quantity of polymers that fractionated on the gel. Low molecular weight polyuronides were first evident in fruit harvested at the turning stage and they constituted the major portion of the polyuronides obtained from fruit at more advanced stages of ripening. The appearance of degraded polyuronides corresponded well with the activity of endo-D-galacturonanase, which appeared to be solely responsible for the degradation of these wall polymers. The cell wall hemicelluloses were also affected during ripening; gel-filtration analyses revealed marked changes in the molecular-weight distribution of these polymers. Hemicelluloses from immature green and mature green fruit were similar chromatographically, whereas those from fruit harvested during ripening showed progressively lower quantities of high molecular weight polymers and higher quantities of low molecular weight polymers (<40,000). These changes coincided with the degradation of the pectic polysaccharides; however, in vitro studies using isolated cell wall showed that pectin degradation occurred independently of the changes in hemicelluloses.

ナルトミカン果皮の老化とリポキシゲナーゼ及びヒドロペルオキシド開裂酵素活性の変化

Activities of lipoxygenase (LOX) and linoleic acid (LA) hydroperoxide (LAHPO) cleavage enzyme in flavedo tissues of Naruto (Citrus medioglobosa hort. ex TANAKA) fruit were investigated as related to aging of the rind. Activities of LOX and LAHPO cleavage enzyme were determined by measuring n-hexanal formed from LA and LAHPO, respectively.LOX activity was high in summer when the fruits were immature-green, low in winter, and again, considerably high in April when the fruits were matureorange. Subsequently, however, the activity decreased as the fruits regreened. The activity of LAHPO cleavage enzyme seasonally varied in parallel with LOX activity, although it was 20-100 times higher than the latter.Fruits harvested at different stages were held at 1 to 25°C, and LOX activities were determined. The higher the storage temperature, the faster the rise in LOX activity. However, as the fruits aged, the temperature which resulted in the highest LOX activity shifted downward (to 15°C). The optimum temperature for the development of color similarly shifted downward, being 25°C for immature-green fruits and 15°C for mature-yellow fruits.Gibberellin (GA, 100ppm) and high temperature (350°C, 48h) treatments of detached fruits not only delayed degreening but also reduced LOX activity, while ethephon (500ppm) treatment increased LOX activity.

Influences of Potassium, Cultivar, and Season on Tomato Graywall and Blotchy Ripening1

Abstract ‘Healani’, ‘Homestead-24’, ‘Walter’, and ‘Flora-Dade’ tomatoes (Lycopersicon esculentum Mill.) were grown with 0, 93, 186, 372, or 744 kg K/ha during spring and fall to determine the influence of K rate, cultivar, and season on the separate fruit disorders of graywall (GW) and blotchy ripening (BR). Susceptibility to GW was determined by inoculating a GW-inducing type of bacteria, Erwinia herbicola (Dye), into the outer pericarp of immature green fruit. All 4 cultivars developed more GW without added K than with it during the spring season. In both field and greenhouse conditions, ‘Flora-Dade’ and ‘Homestead-24’ were more resistant to GW than ‘Healani’ and ‘Walter’. Natural GW, contrasted to bacterially induced GW, occurred in ‘Healani’ and ‘Homestead-24’ fruit grown with low K concentrations in a sand culture experiment. Both cultivars were free of natural GW with the high-K treatment. ‘Flora-Dade’ was resistant to natural GW under all K treatments. Fruit from all cultivars had significantly less BR with K fertilization in both seasons. External blotchy ripening (EBR) and internal blotchy ripening (IBR) were more severe in the spring than in the fall. ‘Healani’ showed resistance to yellow shoulder, the primary EBR symptom, which was severe during the spring in all other culti vars. ‘Healani’ was generally the most BR-resistant cultivar and ‘Flora-Dade’ the most BR-susceptible. Pericarp K concentration increased with K rate in all cultivars during both seasons, but differences in susceptibility to BR between cultivars were not associated with differences in pericarp K, Ca, Mg, or P content.

Superoxide dismutase: A possible protective agent against sunscald in tomatoes (lycopersicon esculentum mill.)

Superoxide dismutase (SOD, EC 1.15.1.1) was concentrated from mature-green tomato fruits by gel chromatography. The enzyme was inhibited by cyanide but not by chloroform-ethanol, and appears to contain zinc and lesser amounts of copper. SOD-activity levels were high in immature green fruits, declined to a minimum in the mature-green and breaker stages known to be most susceptible to sunscald damage, increased again until the fruits were pink, and finally decreased through the red-ripe and overripe stages to the level of the mature-green fruit. When tolerance to sunscald damage was induced in mature-green fruits by controlled temperature treatment and samples of the fruits were challenged at various times during this process with a combined heat-and-light treatment known to cause sunscald, SOD activity was found to be inversely related to the susceptibility of the fruit to sunscald damage. It is suggested that superoxide is involved in sunscald injury to tomatoes and that tolerance is acquired through increases in SOD activity. Possibly SOD acts as a general protective agent against photodynamic damage to green tissues in plants that have become conditioned as the result of normal diurnal temperature fluctuations.

Phenolic constituents of tomato fruit cuticles

Abstract Chalconaringenin, naringenin, naringenin-7-glucoside, and m - and p -coumaric acids have been identified in the fruit cuticles of three tomato cultivars. The phenolic content of the cuticles increased substantially during fruit development, those from immature green and mature ripe fruits of cv Ailsa Craig yielding respectively 2.8 and 61 μg/cm 2 (representing 1.4 and 6% of the total membrane wt). Coumaric acids, present only in the ‘cutin-bound’ phenolics, increased from 2 to 24 μg/cm 2 during fruit development. Flavonoids, synthesized mainly during the climacteric, occurred free in the epicuticular (0.3–7.2 μg/cm 2 ) and cuticular (0.7–5.7 μg/cm 2 ) phenolics but the major part of this class of constituents in ripe fruit cuticles was also ‘bound’ to the cutin matrix (30–43 μg/cm 2 ). The composition of the flavonoid fraction was controlled by the spectral quality of incident radiation, red light favouring the formation of chalconaringenin.

Effect of Ethephon Latex Stimulant on Papaya(Carica PapayaL.)

SummaryThe effect of ethephon latex stimulant mixed in coconut oil and applied to immature green fruits of Co.2 papaya was studied in respect of papain yield and quality of fruits. Papain yield could be increased four-fold over the control by the application of ethephon latex stimulant at 34 mM in coconut oil. Ethephon also improved the quality of papain, and also the quality of fruits by increasing total sugars and reducing sugars and decreasing acidity.

Glutamate oxaloacetate transaminase activity in developing Lycopersicon esculentum fruit

Glutamate oxaloacetate transaminase (GOT) occurs in both the mitochondrial and cytoplasmic fractions from tomato fruit tissue. Changes in activity of the enzyme from fruit at selected developmental stages have been followed. The combined activity fell from the immature green stage to the full red condition whilst the proportion in the mitochondria reached a peak in green-orange fruit. The activity of cytoplasmic, but not mitochondrial, GOT was stimulated by the addition of pyridoxal-5-phosphate. In the green areas of fruit showing blotchy ripening, the combined activity was equivalent to that in normal immature green fruit but with a much higher proportion of the activity in the mitochondria. Mitochondrial GOT could constitute a system in ripening tomato fruit whereby the accumulation of inhibitory concentrations of oxaloacetate affecting the oxidation of succinate and malate might be controlled.

Chlorophyll in Citron (Citrus medica L.)

The variation in the chlorophyll content of citrons was determined at different stages of maturity and at different depths in the mature green fruit. Fruit at different stages of maturity (immature green, mature green, turning ripe, and ripe) was selected from a commercial farm in Adjuntas, Puerto Rico. An examination of the endocarp revealed that it was of a greenish tint in the immature green fruit, greenish yellow in the mature green, completely yellow in the turning ripe, and whitish yellow or cream in the fully ripe fruit. Spectrophotometric determinations were made at different depths of the fruit, showing that the chlorophyll content was highest in the immature green fruit, with the mature green following closely. The chlorophyll content of fruit turning ripe was substantially lower than in the first two stages of maturity but higher than in the ripe fruit. The chlorophyll content of the citron diminishes considerably from one tissue layer to another as one cuts deeper into the fruit. Nevertheless, tissues of immature and mature green fruit contain a good amount of green pigment at greater depths. Because greenness is a characteristic index of quality in candied citron, it is advisable to use immature and mature green fruit for this purpose.

The effect of 2-(4-chlorophenylthio)-triethylamine hydrochloride on the formation of carotenoids in citrus

2-(4-Chlorophenylthio)triethylamine hydrochloride (CPTA) has a profound effect on the formation of carotenoids in the fruit of the trigeneric citrus hybrid Sinton citrangequat. When CPTA is applied to the immature green fruit and the fruit is allowed to ripen to full maturity and color, lycopene accumulates as the main pigment and is responsible for the rich color in the flavedo. Synthesis of methylketone carotenoids which normally produce the red color in the flavedo is inhibited. Treatment with CPTA after the fruits had attained near full maturity and color results in the accumulation of lycopene as a major pigment; no response is apparent in the previously formed methylketone carotenoids. Treatment with CPTA at immature green, mature green or nearly mature stages of fruit development, stimulates the synthesis of lycopene as the principal pigment or as a major pigment depending on stage of development.

Cucurbitacin B Δ23-reductase from Cucurbita maxima: I. Assay methods, isolation and purification

1. 1.Spectrophotometric and chromatographic assay methods were developed for cucurbitacin B Δ 23-reductase (NAD(P)H:cucurbitacin B Δ 23-oxidoreductase). One spectrophotometric method is based on the decrease in absorbance at 340 mμ in the presence of NADPH or NADH as electron donor while another method is based on the decrease in absorbance at 228 mμ as a result of the reduction of the Δ 23-bond in the side chain of cucurbitacin B. 2. 2.The optimum pH of the enzyme was 6.65. 3. 3.Final proof was obtained for the reduction of the Δ 23-bond in the side chain of cucurbitacin B. 4. 4.Cucurbitacin B Δ 23-reductase was isolated from 7.1 kg of immature Green Hubbard fruits by extraction, centrifugation, alcohol fractionation, heat precipitation, pH precipitation, DEAE-cellulose chromatography and Sephadex G-75 gel filtration. The yield was 24 mg and the final enrichment 142.4. 5. 5.The results of paper electrophoresis and ultracentrifugation indicated a homogeneous preparation with a sedimentation coefficient of 2.96 S. 6. 6.Due to the fact that this enzyme falls in the class of the oxidorduetases with NADPH and NADH as the elctron donors, it is proposed that the enzyme should be called NAD(P)H:cucurbitacin B Δ 23-oxidoreductase and it would be classifiable under the number EC 1.6.99.

Phorate Residues in Tomato Fruit and Foliage1

Phorate and oxidative metabolite residues in tomato fruit and foliage were determined by the cholinesterase inhibition procedure. In 10% granular form, up to 5 pounds active photate was applied in bands in soil furrows on either side of the row at transplanting and later dates. Fruit samples contained less than 0.10 p.p.m. phorate residues regardless of whether sampled in the immature green, mature green or pink ripe stage of development. Subsequent ill vitro oxidation of fruit resulted ill slightly greater cholinesterase ill only the immature green tomato fruit. Cholinesterase inhibiting residues in the tomato foliage range from less than 0.10 p.p.m. to 4.0 p.p.m. depending on prior treatments and sampling dates. Residues in the tomato foliage following a number of treatments appeared to approach a maximum at two periods of plant development. These peak residue periods in the foliage were usually correlated with preceding periods of relatively high field temperatures and ample rainfall. Control of serpentine leaf miners (Liriomyza brassicae (Riley)) was effective for at least 2 months after transplanting following application of 3 or 5 pounds of active phorate per acre to the soil.