F. Afreen

Melatonin in Glycyrrhiza uralensis : response of plant roots to spectral quality of light and UV-B radiation

Abstract:  Melatonin (N‐acetyl‐5‐methoxytryptamine) is known to be synthesized and secreted by the pineal gland in vertebrates. Evidence for the occurrence of melatonin in the roots of Glycyrrhiza uralensis plants and the response of this plant to the spectral quality of light including red, blue and white light (control) and UV‐B radiation (280–315 nm) for the synthesis of melatonin were investigated. Melatonin was extracted and quantified in seed, root, leaf and stem tissues and results revealed that the root tissues contained the highest concentration of melatonin; melatonin concentrations also increased with plant development. After 3 months of growth under red, blue and white fluorescent lamps, the melatonin concentrations were highest in red light exposed plants and varied depending on the wavelength of light spectrum in the following order red ≫ blue ≥ white light. Interestingly, in a more mature plant (6 months) melatonin concentration was increased considerably; the increments in concentration were X4, X5 and X3 in 6‐month‐old red, blue and white light exposed (control) plants, respectively. The difference in melatonin concentrations between blue and white light exposed (control) plants was not significant. The concentration of melatonin quantified in the root tissues was highest in the plants exposed to high intensity UV‐B radiation for 3 days followed by low intensity UV‐B radiation for 15 days. The reduction of melatonin under longer periods of UV‐B exposure indicates that melatonin synthesis may be related to the integrated (intensity and duration) value of UV‐B irradiation. Melatonin in G. uralensis plant is presumably for protection against oxidative damage caused as a response to UV irradiation.

Photoautotrophic (sugar-free medium) Micropropagation as a New Micropropagation and Transplant Production System

Preface Contributors Acknowledgements 1. Introduction T. Kozai 2. Units and terminology use for the studies of photoautotrophic micropropagation T. Kozai, C. Kubota 3. Concepts, definitions, ventilation methods, advantages and disadvantages T. Kozai, C. Kubota 4. In vitro aerial environments and their effects on growth and development of plants T. Kozai, C. Kubota 5. In vitro root zone environments and their effects on growth and development of plants T. Kozai, C. Kubota 6. Physiological and anatomical characteristics of in vitro photoautotrophic plants F. Afreen 7. Photoautotrophic plant conversion in the process of somatic embryogenesis F. Afreen, S.M.A. Zobayed 8. Photoautotrophic micropropagation of woody species Q.T. Nguyen, T. Kozai 9. Ventilation in micropropagation S.M.A. Zobayed 10. A commercialized photoautotrophic micropropagation system using large vessels with forced ventilation Y. Xiao, T. Kozai 11. Low temperature storage of plants under dim light C. Kubota 12. Modelling and simulation for production planning in photoautotrophic micropropagation C. Kubota 13. Modelling and simulation in photoautotrophic micropropagation G. Niu 14. Frequently asked questions C. Kubota, T. Kozai 15. Plant species successfully micropropagated photoautotrophically C. Kubota, F. Afreen, S.M.A. Zobayed 16. Reconsideration of conventional micropropagation systems T. Kozai 17. Closed systems with lamps for high quality transplant production at low costs using minimum resources T. Kozai 18. Concluding remarks S.M.A. Zobayed, F. Afreen Subject Index

RECENT ADVANCEMENT IN RESEARCH ON PHOTOAUTOTROPHIC MICROPROPAGATION USING LARGE CULTURE VESSELS WITH FORCED VENTILATION

SummarySuccessful fundamental or basic research, while being stimulated by applied studies, provides the development of new technologies for the benefit of mankind. Photoautotrophic micropropagation or micropropagation using sugar-free medium is no exception from this generalization. The concept of photoautotrophic micropropagation is derived from research that revealed the relatively high photosynthetic abilities of chlorophyllous cultures such as leafy explants and plantlets in vitro. To meet the ever-increasing demand for quality transplants, the scaling-up of photoautotrophic micropropagation systems, for commercialization, has become necessary. This article reviews the recent advancement in the development and utilization of large culture vessels for photoautotrophic micropropagation with special emphasis on the feasibility of the system for the commercial-scale propagation. The review also includes choices for supporting material, ventilation type, planting density, vessel volume, and vessel sterilization procedure, and problems and solutions to achieve uniform growth in a large culture vessel. A case study of the commercial application of a photoautotrophic micropropagation system using large culture vessles, which recently has been established in Kunming, China, is also presented in this article.

Physiology of Eucalyptus plantlets grown photoautotrophically in a scaled-up vessel

SummaryNodal cuttings of Eucalyptus camaldulensis L. plantlets were cultured photoautotrophically (sugar-free nutrient medium and with enriched CO2 and high photosynthetic photon flux) in a scaled-up vessel (volume 4.0 liters) under forced ventilation (SV-treatment). After 28 d of culture, physiological aspects of the plantlets were compared with plantlets grown photomixotrophically (20 g l−1 sucrose in the medium) in a Magenta vessel (volume 0.4 liters) under natural ventilation (control). In the SV-treatment net photosynthetic rates were enhanced, normal stomatal closing and opening were observed, and the epicuticular leaf-wax content was significantly higher than the control. The anatomical study showed well-organized palisade and spongy mesophyll layers of SV leaves. The SV-treatment also allowed in vitro acclimatization, and after transplanting ex vitro, the transpiration rate and the percent water loss was lower than those of the control and thus the SV plantlets acclimatized easily ex vitro.

Necessity and Concept of the Closed Transplant Production System

We are requested to develop a concept, a methodology and an industry to solve the global issues on environmental pollution and shortages of food, feed, phytomass (plant biomass) and natural resources including fossil fuels and usable water. These issues are considered to become more and more serious on a larger scale in the forthcoming decades. In order to solve those issues in the 21st Century, billions of plants are required every year not only for food, feed and environment conservation, but also for alternative raw materials to produce energy, bio-degradable plastics and many other industrial products. By using plant-derived products, we can minimize the environmental pollution and the use of fossil fuels and atomic power. Then, we need billions of quality transplants (small plants) every year to be grown in the fields with maximum use of solar energy and minimum use of resources under harsh environmental conditions. These quality transplants can be produced only under carefully controlled environments. Bioengineering is expected to provide a useful concept and a methodology to develop the bioindustry for solving the above global issues substantially. In bioengineering, the global and local flows of energy, mass (or materials) and information are analyzed with special attention to the organic and inorganic metabolisms of plants, animals including humans and microorganisms. Concept of ‘closed-type or closed production systems’ is essential to develop a production system with minimum use of resources and with minimum environmental pollution. This concept can be applied to develop a closed-type transplant production system with artificial lighting for producing billions of quality transplants with minimum use of resources and with minimum environmental pollution. Research and development of the closed transplant production systems will create a new field of bioengineering and bioindustry.

ENHANCED GROWTH AND QUALITY OF ST. JOHN'S WORT (HYPERICUM PERFORATUM L.) UNDER PHOTOAUTOTROPHIC IN VITRO CONDITIONS

SummaryPhotomixotrophic (Pm) micropropagation systems (ones that use a sugar-containing medium) have been used by many rescarchers for transplant production of St. Johns wort. However, these methods have not yet been adopted for commercial applications, probably due to the low percentage of regeneration in vitro, and a low growth rate after transplanting ex vitro. In contrast, it is well known that the use of a photoautotrophic (Pa) micropropagation system (one that uses sugar-free medium) can promote the growth and improve the quality of plantlets in vitro, and enhance the growth during acclimatization for many plant species. In the current study, leafy nodal cuttings were cultured under Pa conditions and the growth and quality were compared with those cultured under Pm conditions. After 21d of culture, Pa conditions enhanced the growth and quality of St. Johns wort plantlets in vitro, and these plantlets showed faster growth after transplantaing ex vitro compared with those cultured under Pm conditions.

Evolution of Culture Vessel for Micropropagation: From Test Tube To Culture Room

To improve the culture conditions for micropropagation, different types of culture vessels and capping systems have been designed. Some of these designs improve the aerial composition in the culture vessel and some for recycling the nutrient medium. This article describes the evolution of different culture vessel and culture systems, with special emphasis on forced ventilation to improve the culture atmosphere and thus to improve the growth and multiplication and also the quality of propagules. By altering the aerial environment of the culture vessel, plantlets can be grown photoautotrophically (sugar free medium) which has many advantages over the photomixotrophic or heterotrophic system. By using forced ventilation and a photoautotrophic culture system, the scaling-up of the culture vessel is possible with high growth rate and survival percentage and with minimum time and space. More recently, this scale-up system has been further extended making the aseptic culture room itself a large culture vessel containing many small sterile trays with plants on the culture shelves and with a common headspace. By using this enlarged system, the production of even more quality transplants was achieved relatively easily.

Physiology of in Vitro Plantlets Grown Photoauto-Trophically

Earlier efforts to improve the growth and multiplication of in vitro grown plantlets have focused mainly on the composition of the nutrient medium and the use of growth regulators. The physiological characteristics of micropropagated plantlets cultured under conventional photomixotrophic/heterotrophic conditions in airtight vessels are often abnormal. Low rates of photosynthesis and transpiration, poor water and mineral uptake, non-functional stornata, lack of organisation of palisade and mesophyll tissues in the leaves and poor root quality are the major short-comings of plantlets grown under conventional micropropagation conditions. Recent research has revealed that the aerial environment of the culture vessel can significantly affects the growth and quality of the plantlets, the duration of culture and the cost of production. The use of a more suitable supporting material than conventional agar can also improve the root growth and quality as well as shoot growth. Most recently, the use of a photoautotrophic culture system (sugar free medium) with forced ventilation and with fibrous rooting substrates was proved to be the best for improving the growth and quality of the plantlets and for reducing production costs. This article discusses various ways of improving the physiological conditions and quality of micropropagated plantlets with special emphasis on the culture atmosphere and the rooting substrate.

Development of photoautotrophy in Coffea somatic embryos enables mass production of clonal transplants

Somatic embryogenesis offers the promise of a cost-effective, large-scale propagation method and is considered as a unique alternative technique to overcome some of the limitations of conventional clonal propagation methods. Production of somatic embryos from cell, tissue and organ cultures may occur directly which involves the formation of an asexual embryo from a single cell or a group of cells on a part of the explant tissue without an intervening callus phase. In this study, the photosynthetic ability of different stage coffee (Coffea arabusta) somatic embryos and the development of photoautotrophy are reported. Results revealed that cotyledonary and converted somatic embryos have the ability to photosynthesise and can be grown under photoautotrophic conditions (with no supply of sugar from the culture medium). The development of photosynthetic ability can be accelerated by placing the somatic embryos in a photosynthetic photon flux of 100 µmol m−2s−1 for at least 14 days. Cotyledonary stage somatic embryos were cultured under photoautotrophic conditions in three different growing systems to develop an optimized protocol for a large-scale embryo-to-plantlet conversion and propagation system. Our results demonstrated that the use of a newly developed temporary root zone immersion bioreactor is effective for the embryo-to-plantlet conversion and enhanced growth under photoautotrophic conditions.

Mass propagation of coffee transplants under scaled-up photoautotrophic micropropagation system

Somatic embryos were obtained from leaf discs of coffee plants cultured in vitro. The main objective of our study was to develop a scaled-up micropropagation system under photoautotrophic conditions (PA) using Coffea arabusta somatic embryos as a model plant. At different developmental stages of somatic embryos (torpedo, precotyledonary, cotyledonary and germinated), the physiological variables in relation to the photosynthetic ability were investigated. Results revealed that cotyledonary and germinated stage embryos were physiologically capable to grow photoautotrophically. However, high photosynthetic photon flux (PPF: 100 μmol m 2 s -1 ) treatment for 14 days increased the photosynthetic efficiency of the somatic embryos and possibly make them more suitable to grow under PA conditions. To confirm these findings the somatic embryos were cultured under PA conditions (sugar-free medium with CO 2 enrichment in the culture vessel environment and high PPF). From the results it was concluded that cotyledonary stage is the earliest stage somatic embryo, which can be successfully grown photoautotrophically for conversion into plantlets. To scale up the plantlet conversion process of coffee somatic embryos under PA conditions a bioreactor was especially designed. The growth and conversion percentage of cotyledonary stage embryos cultured in the newly developed bioreactor were compared with those of commercially available systems such as RITA temporary immersion bioreactor and Magenta box. Results revealed that the growth, percent conversion and ex vitro survival of plants were highest in the newly developed bioreactor.