caryophyllus L.) (Kozai and Iwanami, 1988) and tobacco (Nicotiana tabacum L.) plants (Pospisilova et al., 1988) were also grown photoautotrophically in the same year (1988). The concept of growing plantlets in a large vessel under photoautotrophic conditions with forced ventilation system was first successfully implemented by Fujiwara et al., (1988). The vessel, volume of 19 L (58 cm long, 28 cm wide and 12 cm high) with an attached air pump for the forced ventilation, was used to enhance the photoautotrophic growth of strawberry (Fragaria x ananassa Duch.) explants and/or plants during the rooting and acclimatization stages. This was an aseptic micro-hydroponic system with a nutrient solution control system. Since then the trend of developing protocols for the in vitro growth of plants under photoautotrophic conditions started and is still continuing and so far nearly 50 different plant species have been reported to grow successfully under photoautotrophic conditions. Among these potato plant has been studied most extensively by many authors (Kozai et al., 1988; Takazawa and Kozai, 1992; Kozai et al., 1992 and 1995b; Tanaka et al., 1992; Miyashita et al., 1997; Kitaya et al., 1995c and 1997a; Fujiwara et al., 1995; Hayashi et al., 1995; Miyashita et al., 1995 and 1996; Roche et al., 1996; Niu. and Kozai, 1997; Niu et al., 1997; Zobayed et al., 1999a; Kim et al., 1999; Xiao et al., 2000; Pruski et al., 2002) followed by sweetpotato (Nagatome et al., 2000, Kozai et al., 1996; Ohyama and Kozai, 1997; Niu et al., 1998; Afreen et al., 1999; Zobayed et al., 1999; Afreen et al., 2000; Zobayed et al., 2000; Heo and Kozai, 1999; Wilson et al., 2000; Kubota et al., 2002).
Studies of in vitro plant growth under photoautotrophic conditions and the conventional photomixotrophic conditions (control) covered a wide range of area including growth, morphology and development, physiology and anatomy, biochemistry and molecular studies. More specifically, biomass accumulation of root, shoot and leaf, ex vitro growth and survival, tuber yield, CO2 and ethylene concentrations, profile of CO2 concentrations in the vessel, multiplication coefficient, low temperature storage, changes in nutrient composition in the medium, nutrient uptake, development of photosynthetic tissues, dark respiration, net photosynthetic rates and plotting the photosynthesis curve, carbon isotope composition, stress response, chlorophyll fluorescence, photosynthetic capacity, photoinhibition, carbohydrate status, chlorophyll and xanthophyll contents, ultrastructure of chloroplast, thylakoid membrane proteins, abscisic acid content, enzyme activities (RuBPC, PEPC), anatomical features of leaves, stomatal density, transpiration, leaf water potential, relative water content, wax content, gene expression and many other aspects have been studied under those conditions. The plant species successfully micropropagated photoautotrophically are listed in the following table. The scientific names along with the common names, the main controlled factors and the measured factors for each of those studies are also presented.
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