Induced accumulation of 20-hydroxyecdysone in cell suspension cultures of Vitex glabrata R.Br.

This study describes the effects of culture medium, culture temperature, sucrose concentration and cholesterol feeding on cell growth and 20-hydroxyecdysone production in suspension cultures of Vitex glabrata, an important medicinal plant in Thailand. Cell growth and 20-hydroxyecdysone production were not significantly different when cells were cultivated on B5 or half-strength MS medium. However, cultivation of V. glabrata cell cultures at 25°C yielded 1.06- and 1.09-fold higher values of cell growth and 20-hydroxyecdysone content, respectively than those at 30°C. Sucrose at 30 and 40 g/L favors the production of 20-hydroxyecdysone in suspension cultures of V. glabrata. Feeding of cholesterol at 5 mg/L, as precursor for biosynthesis of 20-hydroxyecdysone, yielded 1.11-fold higher accumulation of 20-hydroxyecdysone than the control cells. Increasing of cholesterol to 10 mg/L resulted in decreased production of 20-hydroxyecdysone.Key words: Vitex glabrata, 20-hydroxyecdysone, suspension culture, cholesterol

Cloning and differential expression of 1- aminocyclopropane-1-carboxylate synthase gene in different floral tissues of Dendrobium ‘anna’ flowers

Cloning of the DenACS from Dendrobium hybrid cultivar Anna was  performed by RT-PCR and nucleotide sequence analysis revealed that the open reading frame of this gene was 1,308 bp in length, encoded for a protein of 435 amino acid residues. The calculated molecular mass of the deduced polypeptide is 48.5 kDa and the predicted isoelectric point is 5.84. The deduced amino acid sequence of the DenACS-encoded protein showed a high degree of identity to those of the ACS from petunia,geranium, carnation and rose. The expression of DenACS was examined by RT-PCR and the results revealed that this gene was highly expressed in flower stage 2 (partially opened flower) and stage 3 (full opened flower) during flower development. It was also expressed in all floral tissues and organs including petal, sepal, pedicel, labellum, stigma, young leaves and roots, but the maximum expression was observed in petal, sepal and pedicel. These results indicated that the orchid DenACS is involved inthe flower opening, flower senescence as well as in vegetative cell growth and development

Ethanol production from Jerusalem artichoke (Helianthus tuberosus L.) by Zymomonas mobilis TISTR548

The selection and characterization of Zymomonas mobilis for ethanol production from Jerusalem artichoke (Helianthus tuberosus L.) juice was investigated. Growth and ethanol production of four Z. mobilis strains isolated in Thailand, that is, TISTR 405, TISTR 548, TISTR 550 and TISTR 551, were compared with those of the type strain Z. mobilis ZM4 (NRRL B-14023) at different temperatures. Among the strains tested, TISTR 548 gave the highest ethanol concentration at 30 to 35°C, as compared to the others. Therefore, this strain was chosen for ethanol production from Jerusalem artichoke juice after acid hydrolysis. The influence of some fermentation factors such as sugar concentration, pH of the fermentation medium, inoculation size and nitrogen source on ethanol production from Jerusalem artichoke juice was determined. The results show that the maximum ethanol concentration (95.9 g/L) with 98% of the theoretical ethanol yield was obtained when the fermentation was carried out in a medium containing 250 g/L total sugars, pH 5.0, inoculation size at 10% and using 0.5 g/L diammonium phosphate as nitrogen source. The maximum theoretical ethanol yield obtained in this study was higher than those previously reported.Key words: Ethanol production, Zymomonas mobilis, thermotolerant microorganism, Jerusalem artichoke

Cloning and molecular characterization of glyceraldehyde-3-phosphate dehydrogenase gene from thermotolerant mushroom, Lentinus polychrous

This study describes the cloning and expression analysis of the heat shock protein gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), in thermotolerant mushroom Lentinus polychrous, one of the most widely cultivated commercial edible mushroom in Thailand. The complete GAPDH coding sequence contained 1,011 bp, encoding for a polypeptide of 337 amino acid residues with the calculated molecular mass of 36.2 kDa and pI of 5.64. Southern blot analysis revealed the presence of a single copy of the GAPDH gene in the L. polychrous genome. The putative amino acidsequence of the L. polychrous GAPDH-encoded protein shared significant sequence identity with other GAPDH proteins from basidiomycetes. Phylogenetic analysis clustered the L. polychrous GAPDH protein with other homobasidiomycetes. Expression analysis of the GAPDH gene by RT-PCR showed that this gene was highly induced not only by heat, but also by cold, ethanol and salt stresses. The GAPDH gene was expressed in both mycelia and fruiting bodies, suggesting that the GAPDH gene product is a heat shock protein which might be involved in the developmental phase of the L. polychrous

Effect of salt stress on growth, inorganic ion and proline accumulation in Thai aromatic rice, Khao Dawk Mali 105, callus culture

The inhibitory effect of salt stress in rice is complex and is one of the main reasons for reduction of plant growth and crop productivity. In the present study, the response of rice callus cultivar Khao Dawk Mali 105 (KDML105), commonly known as Thai jasmine rice, to salt stress was examined. Calluscultures of KDML105 rice were exposed to salt stress by placing on Murashige and Skoog (MS) medium containing 250 mM NaCl. Growth, water content, proline and inorganic ion content in rice cells weremeasured during stress treatment for 8 - 10 days. After prolonged exposure to salt stress, growth and water content of rice cells were progressively decreased. Rice cells accumulated high level of Na+during stress, whereas the accumulation of K+ and Ca2+ was decreased. High level of Na+ inside the cells inhibited the K+ uptake resulted in increase level of the Na+/K+ ratio. In addition, salt stress alsocaused an increase in the accumulation of proline. This result suggested that proline may play a crucial role in protecting the KDML105 rice cells under salt stress