Non-thermal stabilization mechanisms of anthocyanins in model and food systems—An overview

The chloroplast structural alteration and the photosynthetic apparatus activity of cherry tomato seedlings were investigated under dysprosium lamp [white light control (C)] and six light-emitting diode (LED) light treatments designated as red (R), blue (B), orange (O), green (G), red and blue (RB), and red, blue, and green (RBG) with the same photosynthetic photon flux density (PPFD) (’320 mmol m s) for 30 days. Compared with C treatment, net photosynthesis of cherry tomato leaves was increased significantly under the light treatments of B, RB, and RBG and reduced under R, O, and G. Chloroplasts of the leaves under the RB treatment were rich in grana and starch granules. Moreover, chloroplasts in leaves under RB seemed to be a distinct boundary between granathylakoid and stromathylakoid. Granathylakoid under treatment B developed normally, but the chloroplasts had few starch granules. Chloroplasts under RBG were similar to those under C. Chloroplasts under R and G were relatively rich in starch granules. However, the distinction between granathylakoid and stromathylakoid under R and G was obscure. Chloroplasts under O were dysplastic. Palisade tissue cells in leaves under RB were especially well-developed and spongy tissue cells under the same treatment were localized in an orderly fashion. However, palisade and spongy tissue cells in leaves under R, O, and G were dysplastic. Stomatal numbers per mm were significantly increased under B, RB, and RBG. The current results suggested blue light seemed to be an essential factor for the growth of cherry tomato plants. Cherry tomato (Solanum lycopersicum Mill.) plants are one of the cultivars of tomato species and annual plants that prefer a high light fluence rate. The fruits of cherry tomato plants have pleasing appearances and a delicious taste and are well accepted by consumers. The photosynthesis and growth of the tomato plants are greatly influenced by the quality and quantity of light (Hiroshi et al., 2000; Kinet, 1977). Nowadays, many kinds of garden crops are cultivated under electric lights such as fluorescent lamps and LEDs. LEDs are becoming especially popular for the cultivation of vegetable crops (Amaki and Hirai, 2008; Goins et al., 1997; Hoenecke et al., 1992; Kim et al., 2004a, 2004b; Schuerger et al., 1997; Tennessen et al., 1994). The quality and quantity of light have been shown to alter the structure and function of chloroplasts in leaves (Albertsson, 2001; Anderson, 1999; Danielsson et al., 2004). The alteration of photosynthesis activity and the structure of granathylakoids and stromathylakoids by the different light treatments is of particular interest (Danielsson et al., 2004; Mustardy and Garab, 2003). Light quality influences the growth of cells and tissue, photosynthetic characteristics (Liu, 1993) and yield of crops, physiological and morphological qualities, and the regulation of stress and aging of leaves (Voskresenskaya et al., 1968). At present, photobiological studies have been mainly focused on the effects of ultraviolet radiation on physiological and morphological characteristics of plants (Holzinger et al., 2006; Holzinger and Lütz, 2006; Michael et al., 2009; Poppe et al., 2002; Zancana et al., 2008). Different treatments of blue, red, and far-red light have been used to analyze the ultrastructure of organelles in leaf cells (McMahon and Kelly, 1996; Schuerger et al., 1997). However, few studies on the ultrastructure and response of cell organelles in leaves exposed to light of different spectral qualities have been carried out. In the present experiment, we investigated the effects of dysprosium lamps (white light, control) and the respective light treatments of LEDs designated as red, blue, orange, green, red and blue, and red, blue and green on the photosynthesis of leaves, ultrastructure of chloroplasts, palisade/spongy tissue, and stomata of cherry tomato leaves. Materials and Methods Plant materials and culture conditions. Seedlings of cherry tomato (Solanum lycopersicum Mill.) (provided by Taiwan Farmers Co.), which developed two leaves after germination, were transplanted and grown in plastic pots containing a mixture of peat and vermiculite (3:1, v/v) under light treatments. The treatments were provided by a dysprosium lamp (It is a high-intensity gas discharge lamp, a new type of metal halide lamp. Its spectrum is similar to the solar spectrum.) (white light, C) (LZ400D/H, 400W; YaHuaNing Co., Nanjing, China) and LEDs designated as R, B, O, G, RB, and RBG. The RB combination of spectral energy distribution was shown to be R:B = 1:1. The RBG combination of spectral energy distribution was shown to be R:B:G = 3:3:1. Except for the power of green lamp in the RBG treatment, which was 3 W, the power of every LED lamp treatment was 9 W. The number of LED lamps in treatments of R, B, and RB was 10 each, whereas the numbers used in treatments O, G, and RBG were 12. Respective LEDs were operated with the same PPFD ( 320 mmol m s) for 30 d. Spectral distribution and total power for each treatment are shown in Figure 1 and Table 1. Seedlings were incubated at 28 C in the daytime and at 18 C at night; relative humidity (RH) was 60% 80%, and daylength of 12 h was used. The light system was designed and made by Nanjing Agricultural University. Measurements of photosynthesis. All measurements were carried out using the young and fully expanded third leaf of cherry tomato plants. PPFD was measured using a quantum sensor (LI-250; LI-COR) and photosynthesis was measured using a photosynthesis instrument (LI-6400; LI-COR). PPFD was set to measure at 800 mmol m s, and the experimental conditions such as leaf temperature, CO2 concentration, and RH were 23 ± 1 C, 380 ± 5 mL L, and 16% to 20%, respectively. Spectral distribution of light treatments was measured by spectroradiometer (OPT-2000; ABDPE Co., Beijing, China). Leaves of three plants per treatment were measured and repeated twice. Chloroplast ultrastructure. Leaf samples were collected after illumination for 3 h at 30 d and placed into 0.2 M phosphate buffer (pH 7.2) containing 2.5% glutaraldehyde and then subjected to suction by a vacuum pump. After that, the samples were placed in a refrigerator at 4 C for 8 h; they were washed Received for publication 30 Aug. 2010. Accepted for publication 25 Nov. 2010. Supported by National Natural Science Foundation (2006AA03A165) and (30972035). Presently Professor Emeritus of Nagoya University. To whom reprint requests should be addressed; e-mail srguo@njau.edu.cn; xuzhigang@njau.edu.cn. HORTSCIENCE VOL. 46(2) FEBRUARY 2011 217 CROP PRODUCTION

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Regulation of Chloroplast Ultrastructure, Cross-section Anatomy of Leaves, and Morphology of Stomata of Cherry Tomato by Different Light Irradiations of Light-emitting Diodes

Fruit-set in tomato (Solanum lycopersicum) depends on gibberellins and auxins (GAs). Here, we show, using the cv MicroTom, that application of N-1-naphthylphthalamic acid (NPA; an inhibitor of auxin transport) to unpollinated ovaries induced parthenocarpic fruit-set, associated with an increase of indole-3-acetic acid (IAA) content, and that this effect was negated by paclobutrazol (an inhibitor of GA biosynthesis). NPA-induced ovaries contained higher content of GA(1) (an active GA) and transcripts of GA biosynthetic genes (SlCPS, SlGA20ox1, and -2). Interestingly, application of NPA to pollinated ovaries prevented their growth, potentially due to supraoptimal IAA accumulation. Plant decapitation and inhibition of auxin transport by NPA from the apical shoot also induced parthenocarpic fruit growth of unpollinated ovaries. Application of IAA to the severed stump negated the plant decapitation effect, indicating that the apical shoot prevents unpollinated ovary growth through IAA transport. Parthenocarpic fruit growth induced by plant decapitation was associated with high levels of GA(1) and was counteracted by paclobutrazol treatment. Plant decapitation also produced changes in transcript levels of genes encoding enzymes of GA biosynthesis (SlCPS and SlGA20ox1) in the ovary, quite similar to those found in NPA-induced fruits. All these results suggest that auxin can have opposing effects on fruit-set, either inducing (when accumulated in the ovary) or repressing (when transported from the apical shoot) that process, and that GAs act as mediators in both cases. The effect of NPA application and decapitation on fruit-set induction was also observed in MicroTom lines bearing introgressed DWARF and SELF-PRUNING wild-type alleles.

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Inhibition of Auxin Transport from the Ovary or from the Apical Shoot Induces Parthenocarpic Fruit-Set in Tomato Mediated by Gibberellins

The growth and photosynthetic characteristics of cherry tomato seedlings were investigated under seven light irradiations such as dysprosium lamps (white light; control, C), red light emitting diodes (LEDs) (R), blue LEDs (B), orange LEDs (O), green LEDs (G), red and blue LEDs (RB) and red, blue and green LEDs (RBG) with the same photosynthetic photon flux density (about 320 μmol m-2 s-1) for 30 days. Morphological appearances of seedlings were significantly different between light treatments, that is, the plants under RB and RBG were shorter and stronger than those under C, while those under O, G and R were higher and weaker. The higher carbohydrate contents were in plants containing blue treatment, B, RB and RBG. Photosynthetic pigments were shown to have significant difference under respective light irradiations of LEDs. The higher photosynthetic pigments were in leaves of seedlings containing blue light treatment, RBG, RB, B, C and G treatments, the lower the pigments were in those with R and O treatments. Net photosynthesis (Pn) was the highest in leaves of seedlings with RB and RBG and the lowest in those with G. Compared with C treatment, light compensation point and light saturation point of seedlings with R, RB and RBG increased, but those with O and G decreased. Electron transport rate (ETR), quantum efficiency of photosystem II photochemistry (ΦPSII), photochemical quenching (qP) and efficiency of excitation energy capture by open PSII reaction centres (Fv′/Fm′) in seedlings with B, RB and RBG treatments were significantly greater than those of the other treatments. Taken together, RB and RBG of LEDs were shown to be beneficial factors for the growth and photosynthesis in cherry tomato seedlings. Key words : Light-emitting diode (LED), light quality, cherry tomato, growth, photosynthetic characteristics.

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Regulation of the growth and photosynthesis of cherry tomato seedlings by different light irradiations of light emitting diodes (LED)

Involvement of auxin and CKs in boron deficiency induced changes in apical dominance of pea plants (Pisum sativum L.).

Petiole length, chlorophyll and carbohydrate levels, and photosynthetic rates of June-bearing strawberry plants as influenced by red-light irradiation during storage under cool conditions

We investigated the reproductive responses of three cultivars of short-day plants to day-extension and night-break treatment with red, blue, and green light-emitting diodes (LEDs). The plants examined were all Malvaceae species: two cultivars of okra [Abelmoschus esculentus (L.) Moeneh.] and a cultivar of native rosella [Abelmoschus moschatus ssp. tuberosus (Span.) Borss.]. To create day extension or night break, we provided supplemental light from LED panels with peak photon emissions of 470 (blue), 520 (green), or 650 (red) nm. Day-extension treatment using red or blue LEDs inhibited flower and bud appearances; the response was especially pronounced with red LEDs. Night-break treatment with red LEDs also delayed flower bud appearance, but night break with blue LEDs did not produce a clear effect. Night break with green light delayed flowering more strongly than blue light but a little less than red light. We concluded that the dark period-regulated reproductive processes of these plants are most sensitive to disruption by red light, closely followed by green light, but that they are insensitive to blue light, especially when the exposure period is short.

https://journals.ashs.org/downloadpdf/journals/hortsci/44/5/article-p1494.pdf

Reproductive Response of Okra and Native Rosella to Long-day Treatment with Red, Blue, and Green Light-emitting Diode Lights

We demonstrated the effect of cooling of the medium on the fruit set of strawberries (Fragaria ·ananassaDuch.)grown onhighbenchesfor forcingculture.The cooling by water evaporation promoted by a fan enabled to cool the medium by an average of several degrees compared with no cooling. When runner plants were transplanted in late summer, cooling accelerated flower bud emergence almost 10 days on the primary axillary branch compared with plants grown in uncooled medium. Also, with cooling, fruit was harvested from the inflorescence of the primary axillary branch almost 10 days earlier. We expect that this technique will allow early transplanting around the end of summer and will shorten the time between fruit set on the terminal inflorescence and that on the inflorescence of the primary axillary branch.

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Effect of cooling of medium on fruit set in high-bench strawberry culture

To investigate whether night break (i.e., the interruption of the dark period by artificial lighting) controls plant flowering sufficiently with treatment on alternate days, we compared the reproductive responses of seven horticultural crop species under a daily night-break treatment, an alternate-day treatment, and no night-break treatment during the short-daylength season. Longday crops of spinach (Spinacia oleracea), petunia (Petunia×hybrida), and godetia (Godetia cvs.) and short-day crops of cosmos (Cosmos bipinnatus), perilla (Perilla ocymoides), zinnia (Zinnia elegans), and Japanese morning glory (Pharbitis nil) were used. The night-break treatment was supplied for 2 hours starting at midnight using red light-emitting diodes. The effect of the alternate-day treatment was much smaller than the effect of the daily treatment in zinnia and Japanese morning glory; was smaller in spinach, godetia and cosmos; and was only slightly smaller in petunia. Budding in perilla was inhibited by both night-break treatments.

Budding Response of Horticultural Crops to Night Break with Red Light on Alternate Days

We investigated the effect of high temperature on the fruit quality of pot-grown strawberry plants with a limited number of fruit in greenhouse and growth chamber experiments In the greenhouse, plants were grown under either normal greenhouse (control) temperatures or in a small plastic tunnel, which held the air temperature a few degrees higher than the control In the growth chamber, the air temperature was set to either 35/20°C (day/night) or 25/20°C The fruits weight content showed no relation to temperature regime Ascorbic acid content was not influenced by high temperature in either experiment However, the anthocyanin content was decreased at high temperature in the growth chamber Because the periods from anthesis to harvesting were almost the same in both temperature regimes, high temperature might reduce the internal content of anthocyanins in marketed fruits

Hiroshi Hamamoto

Papers

Petiole length, chlorophyll and carbohydrate levels, and photosynthetic rates of June-bearing strawberry plants as influenced by red-light irradiation during storage under cool conditions

Reproductive Response of Okra and Native Rosella to Long-day Treatment with Red, Blue, and Green Light-emitting Diode Lights

Effect of cooling of medium on fruit set in high-bench strawberry culture

Budding Response of Horticultural Crops to Night Break with Red Light on Alternate Days

Effect of High Temperature on Fruit Quality of Pot-Grown Strawberry Plants