Chieri Kubota

Environmental control for the large-scale production of plants through in vitro techniques

Leafy or chlorophyllous explants of a number of plant species currently micropropagated have been found to have high photosynthetic ability. Their growth and development have been promoted on sugar-free medium rather than on sugar-containing medium, provided that the environmental factors, such as CO2 concentration, light intensity and relative humidity, are controlled for promoting photosynthesis and transpiration of explants/shoots/plantlets in vitro. Thus, environmental control is essential for promoting photosynthetic growth and development of in vitro plantlets.Several types of sugar-free (photoautotrophic) culture systems for large-scale micropropagation of plants have been developed. Advantages of sugar-free over conventional (heterotrophic or photomixotrophic) micropropagation systems are as follows: growth and development of plantlets in vitro are faster and more uniform, plantlets in vitro have less physiological and morphological disorders, biological contamination in vitro is less, plantlets have a higher percentage of survival during acclimatization ex vitro, and larger culture vessels could be used because of less biological contamination. Hence, production costs could be reduced and plant quality could be improved significantly with photoautotrophic micropropagation. Methods for the measurement and control of in vitro environments and the beneficial effects of environmental control on photosynthetic growth, development, and morphogenesis in large-scale production of micropropagated plantlets are presented.

Cherries and Health: A Review

Cherries, and in particular sweet cherries, are a nutritionally dense food rich in anthocyanins, quercetin, hydroxycinnamates, potassium, fiber, vitamin C, carotenoids, and melatonin. UV concentration, degree of ripeness, postharvest storage conditions, and processing, each can significantly alter the amounts of nutrients and bioactive components. These constituent nutrients and bioactive food components support the potential preventive health benefits of cherry intake in relation to cancer, cardiovascular disease, diabetes, inflammatory diseases, and Alzheimers disease. Mechanistically, cherries exhibit relatively high antioxidant activity, low glycemic response, COX 1 and 2 enzyme inhibition, and other anti-carcinogenic effects in vitro and in animal experiments. Well-designed cherry feeding studies are needed to further substantiate any health benefits in humans.

Salt in irrigation water affects the nutritional and visual properties of romaine lettuce (Lactuca sativa L.).

The influence of salinity stress on the growth, appearance, and nutritional compounds, especially phenolic compounds and carotenoids, of romaine lettuce (Lactuca sativa L.), a low salt tolerant plant, was studied. The dry weight, height, and color of the lettuce plants were significantly changed by long-term irrigation (15 days) with higher NaCl concentration (i.e., >100 mM). However, no significant differences were observed in the growth and appearance among the control, all short-term treatments (2 days; 50, 100, 500, and 1000 mM), and long-term irrigation with low salt concentration. Moreover, in romaine lettuce treated with long-term irrigation with 5 mM NaCl, the total carotenoid content increased without color change, and the contents of major carotenoids in romaine lettuce, lutein and beta-carotene, increased 37 and 80%, respectively. No differences were observed in lutein and beta-carotene contents in short-term-treated lettuce. The phenolic content of the romaine lettuce declined with short-term salt irrigation, whereas there were no significant differences among treatments exposed to long-term irrigation. This research indicates that long-term irrigation with relatively low salt concentration, rather than short-term irrigation with high salt concentration, can increase carotenoid content in romaine lettuce without causing a tradeoff in yield or visual quality.

Transplant Production in the 21st Century

Preface. 1: Closed transplant production systems. Necessity and concept of the closed transplant production system T. Kozai, et al. Closed transplant production system at Chiba University C. Chun, T. Kozai. Electric energy, water and carbon dioxide utilization efficiencies of a closed-type transplant production system K. Ohyama, et al. Microprecision irrigation system for transplant production H. Murase. Design concepts of computerized support systems for large-scale transplant production T. Hoshi, et al. 2: Technology in transplant production. Modeling, measurement and environmental control for transplant production. Modeling and simulation in transplant production under controlled environment C. Kubota. Object-oriented analysis and modeling of closed plant production systems D.H. Fleisher, K.C. Ting. Estimating cuticle resistance of seedling shoot tips based on the Penman-Monteith model H. Shimizu, R.D. Heins. Measurement of pH in guard cells using a confocal laser scanning microscope M. Yabusaki, et al. Does electrolyzed-reduced water protect plants from photoinhibition? K. Iwabuchi, et al. Environmental control for improved plant quality within controlled environment plant production systems S.T. Kania, G.A. Ciacomelli. Environmental engineering for transplant production C. Kirdmanee, K. Mosaleeyanon. Effects of air current on transpiration and net photosynthetic rates of plants in a closed plant production system Y. Kitaya, et al. Effects of air temperature, relative humidity and photosynthetic photon flux on the evapotranspiration rate of grafted seedlings under artificial lighting Y.H. Kim. Growth of tomato (Lycopersicon esculentum Mill.) plus transplants in a closed system at relatively highair current speeds -- A preliminary study W. Chintakovid, T. Kozai. Advances and current limitations of plug transplant technology in Korea B.R. Jeong. Lighting strategies for transplant production. A review on artificial lighting of tissue cultures and transplants W. Fang, R.C. Jao. Light emitting diodes (LEDs) as a radiation source for micropropagation of strawberry D.T. Nhut, et al. Application of red laser diode as a light source for plant production A. Yamazaki, et al. Effective vegetable transplant production programs for closed-type systems under different lighting regimes T. Maruo, et al. Photoautotrophic micropropagation in a natural light environment J. Adelberg, et al. High-quality transplant production. Production of value-added transplants in closed systems with artificial lighting H.-H. Kim, T. Kozai. High quality plug-transplants produced in a closed system enables pot-transplant production of pansy in the summer Y. Omura, et al. Yield and growth of sweetpotato using plug transplants as affected by their ages and planting depths A.F.M. Saiful Islam, et al. Yield and growth of sweetpotato using plug transplants as affected by cell volume of plug tray and type of cutting D. He, et al. Production of medical plant species in sterile, controlled environments S.J. Murch, et al. Effect of air temperature on tipburn incidence of butterhead and leaf lettuce in a plant factory K.Y. Choi, et al. Evaluation of lettuce cultivars suitable for closed plant production system M. Ishii, et al. Root growth subsequent to transplanting in plug-grown cabbage seedlings S. Yoshida. Effective storage conditions for subsequent growth enhancement of Ficus carica L. cuttings M. Takagaki, et al. 3: Biotechnology for tra

Growth and Water Relations of Paulownia fortunei Under Photomixotrophic and Photoautotrophic Conditions

The growth and water relations of Paulownia fortunei in photoautotrophic cultures (nutrient medium lacking sucrose and growth regulator) with CO2 enrichment (PWAH) or without CO2 enrichment (PWAL) were compared with those in photomixotrophic shoot (PWC; 30 g dm−3 sucrose and 0.3 mg dm−3 N6-benzyladenine) and root cultures (PWR; 0.3 mg dm−3 indole-3-butyric acid). The photoautotrophic and photomixotrophic cultures were incubated under photosynthetic photon flux 125 and 60 μmol m−2 s−1, respectively. 100 % sprouting and significantly higher number of shoots (1.6) were obtained with PWAH as compared to PWAL and PWC. PWAH and PWAL stimulated spontaneous rooting from the cut end of axillary shoots. In PWAH, 84 % of shoots rooted with an average of 5.9 roots per shoot and 4.0 cm of root length in 21 d. Rooting of photomixotrophic shoot cultures were stimulated by an auxin treatment. In this case, 98.3 % of shoots were rooted with an average of 4.6 roots per shoot and 1.9 cm length. A microscopic observation on leaf abaxial surface prints from photomixotrophic shoot and root cultures showed widely open (6 – 8 μm) spherical stomata (12 – 14 μm) and from photoautotrophic cultures elliptical stomata (10 – 12 μm) with narrow openings (3 – 4 μm). Leaves from photomixo-trophic cultures had higher stomatal index as compared to photoautotrophic cultures. The rate of moisture loss from detached leaves was not varying significantly in different cultures.

Developing a Photoautotrophic Micropropagation System for Woody Plants

in vitro including cotyledonary stage somatic embryos have the ability to grow photoautotrophically (without sugar in the culture medium), and that the low or negative net photosynthetic rate of plants in vitro is due not to poor photosynthetic ability, but to the low CO2 concentration in the air-tight culture vessel during the photoperiod. Furthermore, we have shown that the photoautotrophic growth of several woody plants in vitro can be significantly promoted by increasing the CO2 concentration and light intensity in the vessel, by decreasing the relative humidity in the vessel, and by using a fibrous or porous supporting material with high air porosity instead of gelling agents such as agar. In this paper, the advantages of photoautotrophic micropropagation in a conventional, small culture vessel with a microporous gas filter for enhancing natural ventilation and in a large culture vessel with a forced ventilation unit are described for woody plants such as acacia (Acacia mangium), coffee (Coffea arabusta), eucalyptus (Eucalyptus camaldlensis), mangosteen (Garcinia mangostana), neem (Azadirachta indica), paulownia (Paulownia fortunei), and pine (Pinus radiata).

Growth and net photosynthetic rates of Eucalyptus tereticornis Smith under photomixotrophic and various photoautotrophic micropropagation conditions

The growth and net photosynthetic rates of shoot cultures of Eucalyptus tereticornis Smith grown under various photoautotrophic conditions (without sucrose in the nutrient medium and with enriched CO2 and high photosynthetic photon flux or PPF) were compared with those of shoot cultures grown under conventional photomixotrophic conditions (30 g l−1 sucrose and 0.3 mg l−1 BA). The shoot height (1.1 cm), number of new nodal segments generated per active explant (3.0) and the multiplication coefficient (2.8) were significantly higher under photomixotrophic conditions (CO) than under various photoautotrophic cultural conditions. The latter included the following treatments; agar with high PPF and CO2 non-enrichment (AL), agar with high PPF and CO2 enrichment (AH) and Florialite with high PPF and CO2 non-enrichment (FL). The difference in growth was less noticeable between Florialite (a mixture of vermiculite and cellulose fiber) in combination with high PPF and CO2 enrichment (FH), and CO. Estimated net photosynthetic rate (NPR) of shoots grown under photomixotrophic conditions was negative at each measuring day (days 7, 14, 21 and 28), whereas the NPR of shoots grown under high PPF and CO2 non-enrichment was positive and increased during the first 14 days of culture and decreased thereafter. Shoots grown under high PPF and CO2 enrichment exhibited an increase in NPR for 21 days and a decrease in NPR for the next 7 days.

Supporting material affects the growth and development of in vitro sweet potato plantlets cultured photoautotrophically

SummaryA comparative study was conducted to optimize the vegetative growth of sweet potato (Ipomoea batatas L. (Lam), cv. Beniazuma) plantlets cultured in vitro in five different types of supporting materials: agar matrix (a seaweed derivative; Kanto Chemical Co. Inc., Tokyo), gellan gum (a Pseudomonas derivative; Kanto Chemical Co. Inc., Tokyo), vermiculite (a kind of hydrous silicates), a mixture of vermiculite and cellulose fiber (Florialite; Nisshinbo Industries, Inc., Tokyo) and cellulose plug (Sorbarod; Baumgartner Rapiers SA., Switzerland). Single nodal cuttings were cultured photoautotrophically (without any sugar in the medium and with enriched CO2 and high photosynthetic photon flux) for 21 d on MS basal medium. Plantlets exhibited the greatest growth when Florialite was used as supporting material. The leaf and root fresh and dry mass were 2.4× and 2.9×, and 2.2× and 2.8× greater, respectively, than those of the plantlets grown in the agar matrix (control). Plantlets cultured in Sorbarod supporting material exhibited the second greatest fresh and dry mass of leaves and roots followed by vermiculite and gellan gum supporting material. The most interesting feature was the development of a large number of fine lateral roots from the main adventitious root in the Florialite treatment. Among the treatments, the highest net photosynthetic rate was evident in the Florialite grown plantlets. The percent porosity of the supporting materials was highest in Sorbarod followed by Florialite and vermiculite. Plantlets transplanted from the Florialite supporting material exhibited the highest acclimatization percentage followed by that of the Sorbarod treatment.

Stomatal characteristics and leaf anatomy of potato plantlets cultured in vitro under photoautotrophic and photomixotrophic conditions

SummaryPotato plantlets (Solanum tuberosum L. cv. Benimaru) were cultured under photoautotrophic (without any sucrose in the nutrient medium and with enriched CO2 and high photosynthetic photon flux) and photomixotrophic conditions (20 g 1−1 sucrose in the medium). Leaf anatomy and stomatal characteristics of the leaves were studied in relation to stomatal size and density. Leaf diffusive resistance, transpiration rate, and wax content of the leaves were also investigated. In the photoautotrophic treatment, stomata behaved normally by closing in the dark and opening in the light. The stomatal density increased twofold compared to that of the photomixotrophic treatment. Relatively thick leaves and an organized palisade layer were observed and the epicuticulal wax content was remarkably higher in this treatment, i.e., seven times greater than that of photomixotrophic treatment. In general, higher diffusive resistance of the leaves was observed than under photomixotrophic conditions; also the resistance increased in darkness and decreased in the light. All these characteristics led the plantlets to have a normal and controlled transpiration rate, which was exceptionally high in the photomixotrophic treatment throughout the light and the dark period.

DEVELOPMENT OF A FORCED VENTILATION MICROPROPAGATION SYSTEM FOR LARGE-SCALE PHOTOAUTOTROPHIC CULTURE AND ITS UTILIZATION IN SWEET POTATO

SummaryA forced ventilation system has been developed for large-scale photoautotrophic micropropagation of chlorophyllous plants. The major goal of the system is to provide a uniform supply of CO2 inside a large culture vessel (volume 3480 ml) to achieve uniform growth of the plantlets. The system has been designed such that sterile nutrient solution can be supplied throughout the culture period, which is essential for long-term culture. Sweet potato (Ipomoea batatas L. Lam., cv. ‘Beniazuma’) was used as a model plant for photoautotrophic culture with stagnant and nonstagnant nutrient solution in large vessels. Growth and net photosynthetic rates of the plantlets were compared with those of the plantlets grown in a small vessel under photoautotrophic conditions (with natural ventilation) and conventional photomixotrophic conditions. The results indicated that the large vessel with the forced ventilation system was effective for improving growth and uniformity of the plantlets and the rate of net photosynthesis. The stagnant nutrient solution condition under photoautotrophic forced ventilation treatment significantly increased the fresh mass of the plantlets; however, percent dry mass was highest in the treatment with nonstagnant nutrient solution condition. The results demonstrated that the conventional photomixotrophic culture system can cause seriously inhibited growth and development.