Byoung Ryong Jeong

Pn-AMPs, the hevein-like proteins from Pharbitis nil confers disease resistance against phytopathogenic fungi in tomato, Lycopersicum esculentum

The antifungal activity of hevein-like proteins has been associated with their chitin-binding activities. Pn-AMP1 and Pn-AMP2, two hevein homologues from Pharbitis nil, show in vitro antifungal activities against both chitin and non-chitin containing fungi. Purified Pn-AMPs retained antifungal activities only under non-reducing conditions. When Pn-AMP2 cDNA was constitutively expressed in tomato (Lycopersicon esculentum) plants under the control of CaMV35S promoter, the transgenic plants showed enhanced resistance against both the non-chitinous fungus Phytophthora capsici, and the chitin-containing fungus Fusarium oxysporum. Thus, the chitin component in the fungal cell wall is not an absolute requirement for Pn-AMPs antifungal activities. These results when considered together suggest that Pn-AMPs have the potential for developing transgenic plants resistant to a wide range of phytopathogenic fungi.

Blue LED light enhances growth, phytochemical contents, and antioxidant enzyme activities of Rehmannia glutinosa cultured in vitro

The objective of the current study is to determine the effect of light quality on enhancement of growth, phytochemicals, antioxidant potential, and antioxidant enzyme activities at in vitro cultures of Rehmannia glutinosa Libosch. In vitro-grown shoot tip explants were cultured on the plant growth regulator (PGR)-free Murashige and Skoog (MS) medium and cultured under a conventional cool white fluorescent light (control), blue light emitting diode (LED) light or red LED light. After four weeks, the growth traits along with total phenol content, total flavonoid content, free radical scavenging activities, and antioxidant enzyme activities were measured. Interestingly, the blue or red LED treatments showed a significant increase in growth parameters compared with the cool white florescent light. In addition, the LED treatments increased the total phenol and flavonoid levels in leaf and root extracts. Furthermore, data on the total antioxidant capacity, reducing power potential, and DPPH radical scavenging capacity also revealed the enhancement of antioxidant capacity under both blue and red LED treatments. Especially, the blue LED treatment significantly increased the antioxidant enzyme activities in both the leaf and root, followed by the red LED treatment. Modulation in the spectral quality particularly by the blue LED induced the antioxidant defense line and was directly correlated with the enhancement of phytochemicals. Therefore, the incorporation of blue or red LED light sources during in vitro propagation of R. glutinosa can be a beneficial way to increase the medicinal values of the plant.

Physiological and Proteomic Analysis in Chloroplasts of Solanum lycopersicum L. under Silicon Efficiency and Salinity Stress

Tomato plants often grow in saline environments in Mediterranean countries where salt accumulation in the soil is a major abiotic stress that limits its productivity. However, silicon (Si) supplementation has been reported to improve tolerance against several forms of abiotic stress. The primary aim of our study was to investigate, using comparative physiological and proteomic approaches, salinity stress in chloroplasts of tomato under silicon supplementation. Tomato seedlings (Solanum lycopersicum L.) were grown in nutrient media in the presence or absence of NaCl and supplemented with silicon for 5 days. Salinity stress caused oxidative damage, followed by a decrease in silicon concentrations in the leaves of the tomato plants. However, supplementation with silicon had an overall protective effect against this stress. The major physiological parameters measured in our studies including total chlorophyll and carotenoid content were largely decreased under salinity stress, but were recovered in the presence of silicon. Insufficient levels of net-photosynthesis, transpiration and stomatal conductance were also largely improved by silicon supplementation. Proteomics analysis of chloroplasts analyzed by 2D-BN-PAGE (second-dimensional blue native polyacrylamide-gel electrophoresis) revealed a high sensitivity of multiprotein complex proteins (MCPs) such as photosystems I (PSI) and II (PSII) to the presence of saline. A significant reduction in cytochrome b6/f and the ATP-synthase complex was also alleviated by silicon during salinity stress, while the complex forms of light harvesting complex trimers and monomers (LHCs) were rapidly up-regulated. Our results suggest that silicon plays an important role in moderating damage to chloroplasts and their metabolism in saline environments. We therefore hypothesize that tomato plants have a greater capacity for tolerating saline stress through the improvement of photosynthetic metabolism and chloroplast proteome expression after silicon supplementation.

Stem elongation and growth of Solanum tuberosum L. in vitro in response to photosynthetic photon flux, photoperiod and difference in photoperiod and dark period temperatures

Abstract Stem elongation and growth of potato plantlets under three DIF (difference in photoperiod and dark period temperatures) levels, −9, 0 and +9, combined with two PPF (photosynthetic photon flux) levels, 70 (low) and 140 (high) μmol m−2 s−1 provided by white cool fluorescent lamps, under 16 h day−1 (long) or 8 h day−1 (short) photoperiods, were studied. Four nodal cuttings were cultured for 21 days on 0.6 × 10−4 m3 MS (Murashige and Skoog, 1962, Physiol. Plant., 15: 473–497) agar (8 kg m−3) medium with no added sugar in 3.7 × 10−3 m3 polycarbonate boxes. Each box had two 10 mm holes covered with microporous filter to facilitate air exchange (3.6 air exchanges per hour). The average daily temperature in the culture room was set the same at 23 °C for all treatments, and CO2 concentration and relative humidity were maintained at 400–500 μmol mol−1 and 50–70%, respectively. Stem length was significantly suppressed under 0 or −9 DIF, high PPF and long photoperiod. Stem diameter, leaf area and number of leaves were significantly enhanced by long photoperiod and high PPF, but affected little by DIF level. Specific leaf area was little affected by photoperiod, but decreased under high PPF and under low DIF. Long photoperiod and high PPF led to an increase in the fresh and dry weights maintaining similar percentage dry matter and to enhanced root growth. Under the same amount of integrated PPF, fresh and dry weights of leaf, stem, root and whole plantlet were significantly higher under the long photoperiod and low PPF conditions than under the short photoperiod and high PPF conditions. Because of suppressed root growth under short photoperiod, shoot to root dry weight ratio increased under short photoperiod, but was not affected by DIF. It is suggested that under photoautotrophic conditions a combination of high PPF level, long photoperiod, and zero or negative DIF produces potato plantlets in vitro of short and thick stem with similar number and increased area of leaves, which are desirable for transfer to ex vitro conditions.

Silicon Promotes Adventitious Shoot Regeneration and Enhances Salinity Tolerance of Ajuga multiflora Bunge by Altering Activity of Antioxidant Enzyme

We investigated the effect of Si concentration on shoot regeneration and salinity tolerance of Ajuga multiflora. Addition of Si to the shoot induction medium significantly increased the frequency of shoot induction. The average number of shoots regenerated per explant decreased on the medium containing NaCl alone, while there was less decrease when the shoot induction medium was supplemented with both NaCl and Si. The shoot induction percentage increased linearly with increasing concentration of Si in the NaCl containing medium. Addition of Si to the shoot induction medium significantly increased SOD, POD, APX, and CAT activity in regenerated shoot buds as compared with the control. The inclusion of Si to the NaCl containing medium significantly increased the SOD activity in leaves and roots, while it decreased POD, APX, and CAT activity in both organs. Scanning electron microscopic analysis showed that there are no distinct differences in the structure of stomata between the control and Si-treated plants. However, NaCl treatment significantly affected the structure and number of stomata as compared to the control. Wavelength dispersive X-ray analysis confirmed the high Si deposition in trichomes of plants grown in the Si containing medium but not in plants grown in the medium without Si.

Influence of silicon supplementation on the growth and tolerance to high temperature in Salvia splendens

In this study, effects of silicon (Si) on the growth and activities of major antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX), and protein profile under high temperature stress were investigated. Salvia splendens ‘Vista Red’ and ‘Sizzler Red’ were grown in a glasshouse and potassium silicate (0 or 100 mg·L−1) was supplemented hydroponically. Overall important growth parameters, chlorophyll content, and biomass were significantly increased by Si application. In both cultivars, more Si deposition occurred in the root, followed by leaf and flower. In both normal and high temperature conditions, supplemented Si increased the activity of SOD, APX, and GPX, while it decreased the CAT activity. In the SDS-PAGE protein profile, three bands responding differentially to the Si treatment were observed. Especially in ‘Vista Red’ treated with Si, a protein band, approximately 46 kDa, was expressed strongly under the temperature stress. Results of this experiment showed that Si not only promoted the growth of salvia, but also played a vital role against temperature stress.

Light Intensity and Photoperiod Influence the Growth and Development of Hydroponically Grown Leaf Lettuce in a Closed-type Plant Factory System

Effect of light provided by various light intensities combined with different photoperiods on the growth and morphogenesis of lettuce (Lactuca sativa L.) ‘Hongyeom Jeockchukmyeon’ in a closed-type plant factory system were evaluated in this study. Four light intensity treatments, i.e., 200, 230, 260, and 290 μmol·m−2·s−1 PPFD, provided from light-emitting diodes (LEDs), with a combination of three different photoperiods 18/6 (1 cycle), 9/3 (2 cycles) or 6/2 (3 cycles) (light/dark) were used. The combination of 290-9/3 (light intensity-photoperiod) showed the highest plant height and fresh shoot weight, while plants grown at 290-18/6 exhibited the greatest root fresh weight, leaf dry weight, and longest root length. The greatest leaf width, maximum number of leaves, and greatest root dry weight were observed in the treatment combination of 290-6/2. Anthocyanin content was found to be highest in the 290-6/2 and lowest in the 200-6/2 treatment, whereas chlorophyll fluorescence was observed to be highest in the 260-6/2 and the lowest in the 290-9/3 treatment. Our data showed that providing a high light intensity of 290 μmol·m−2·s−1 PPFD with a shorter photoperiod of 6/2 (light/dark) resulted in good plant growth and development of lettuce, whereas growth at light intensities of 230 or 260 μmol·m−2·s−1 PPFD with longer photoperiods of 18/6 and 9/3 (light/dark) resulted in good growth as well as higher photosynthetic capacity.

Silicon alleviates salt stress by modulating antioxidant enzyme activities in Dianthus caryophyllus ‘Tula’

Although silicon (Si) is not considered as an essential element, it is beneficial to the plant growth. Its effect is more evident under abiotic and biotic stress conditions. The objective of this study is to investigate the role of Si on the in vitro growth and resistance to salt stress of Dianthus caryophyllus ‘Tula’. The experiment was designed as a factorial design with 0, 50, or 100 mg·L−1 of potassium silicate (K2SiO3) in combination with 0, 50, or 100 mM sodium chloride (NaCl). The treatment of 50 mg·L−1 Si improved the growth of plant. However, the treatment of Si at 100 mg·L−1 reduced the growth. Although NaCl retarded the growth, addition of Si along with NaCl to the culture medium mitigated the effect of NaCl. A primary defense line by Si to overcome the photosynthetic depression was apparent from the increased chlorophyll content in the Si + NaCl treatment as compared to the treatment of NaCl alone. Enhancement of growth and resistance to salinity by Si was thought to be due to the modulation in activity of antioxidant enzymes, such as superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase. Therefore, our results suggested that 50 mg·L−1 Si supplementation could be optimal for improved growth in vitro and enhanced resistance against salinity in D. caryophyllus ‘Tula’.

Light source and CO2 concentration affect growth and anthocyanin content of lettuce under controlled environment

The effect of light source and CO2 concentration on the growth and anthocyanin content of lettuce (Lactuca sativa L. ‘Seonhong Jeokchukmyeon’) grown in growth chambers was examined. The plant was grown under 140 μmol· m−2·s−1 PPF provided by either cool white fluorescent lamps (F, the control), white (W) light emitting diodes (LEDs), or a 8:1:1 mixture of red, blue and white (RBW) LEDs. Carbon dioxide concentration of the atmosphere was maintained at either 350, 700, or 1,000 μmol·mol−1. The RBW treatment promoted vegetative growth of the shoot and root. Chlorophyll fluorescence (Fv/Fm) was not significantly affected by the light source and CO2 concentration. Total anthocyanin content of the plant supplied with 1,000 mol·mol−1 CO2 was the greatest in the F treatment. Photosynthetic rate significantly increased with the increasing CO2 concentration. These results suggested that the RBW which provided a wider spectrum of PAR and the highest CO2 concentration provided the most the suitable environment condition for vegetative growth of lettuce among the tested light sources. To obtain plants with even higher quality, especially having greater content of anthocyanin, however, more considerations on supplemental light source including white LED are necessary in terms of optimum intensity, photoperiod, and optimum ratios of mixing with other LEDs.

Silicon Supply through the Subirrigation System Affects Growth of Three Chrysanthemum Cultivars

The effect of silicon (Si) treatment on the growth of three chrysanthemum cultivars grown in a soilless substrate was evaluated. Rooted terminal cuttings of Dendranthema grandiflorum ‘Gaya Pink’, ‘Lemmon Tree’, and ‘White Angel’ were transplanted into pots containing a coir-based substrate. A nutrient solution containing 0, 50, or 100 mg·L−1 Si from potassium silicate was supplied once a day through a subirrigation system. Application of Si significantly increased the plant height, stem diameter, number of branches, and chlorophyll content, as compared to the control. Addition of Si at 50 and 100 mg·L−1 into the nutrient solution significantly enhanced number and size of flowers, respectively. When plants were treated with Si necrotic lesions appeared in the older leaves at the beginning of the flowering stage. Concentrations of phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg), and zinc (Zn) in the leaves increased, while the concentrations of potassium (K), boron (B), copper (Cu), iron (Fe), and manganese (Mn) decreased with the increasing Si concentration in the nutrient solution. Among the cultivars, ‘Lemmon Tree’ contained the greatest Si concentration (1364 μg·g−1) followed by ‘Gaya Pink’ (1158 μg·g−1) and ‘White Angel’ (586 μg·g−1).