Hiromu Ohashi

Induction of rosmarinic acid biosynthesis in Lithospermum erythrorhizon cell suspension cultures by yeast extract

SummaryA transient increase in rosmarinic acid (RA) content in cultured cells of Lithospermum erythrorhizon was observed after addition of yeast extract (YE) to the suspension cultures, reaching a maximum at 24 hr. The highest increase of the RA content (2.5-fold) was obtained when 6-day-old cells in the exponential growth phase were treated with YE. Preceding the induced RA accumulation, phenylalanine ammonia-lyase (PAL) activity increased rapidly, whereas tyrosine aminotransferase (TAT) activity was largely unaffected by the treatment. The incorporation of both 14C-phenylalanine and 14C-tyrosine into RA was enhanced in the YE-treated cells, consistent with increased synthesis of the ester.

Glucosylation of salicyl alcohol in cultured plant cells

Abstract Salicin and isosalicin were identified as a product of glucosylation of salicyl alcohol in Lithospermum erythrorhizon suspension cultures while in Datura innoxia suspension cultures only isosalicin was isolated as a glucosylation product. In suspension cultures from seven different plant species examined, Gardenia jasminoides and L. erythrorhizon cultured cells could produce salicin from salicyl alcohol while others produced predominantly isosalicin.

Anthocyanin production in callus cultures of roselle (Hibiscus sabdariffa L.).

Callus tissues derived from seedlings of roselle (Hibiscus sabdariffa L.) were shown to produce two cyanidin glycosides as major anthocyanin pigments. Both callus growth and anthocyanin synthesis were remarkably stimulated by 2,4-dichlorophenoxyacetic acid. The highest anthocyanin yield was observed when 1 μM 2,4-D in combination with 0.1–1 μM kinetin was supplemented to the culture medium. In contrast, gibberellic acid showed inhibitory effect on anthocyanin production.

Enzymatic determination of stevioside in Stevia rebaudiana

Abstract A simple enzymatic method is described for the determination of stevioside in Stevia rebaudiana . The method is based on the hydrolysis of stevioside with crude hesperidinase. The reaction is followed by monitoring the production of glucose with a glucose oxidase-peroxidase-2, 2′-azino-di-(3-ethylbenzothiazoline-6-sulfonic acid) system. The results for the stevioside content in S. rebaudiana leaves correlate with those obtained by other methods. The stevioside content in S. rebaudiana plants showed large variation.

Effect of substituent groups on the glucosyl conjugation of xenobiotic phenols by cultured cells of Gardenia jasminoides

Phenol, nitrophenols and hydroxyphenols added exogenously to Gardenia jasminoides Ellis cell suspension cultures were conjugated to form the corresponding β,d-monoglucosides. The reaction proceeded linearly after the addition of the substrates, indicating participation of constitutive glucosyltransferases in the cultured cells. Nitro substitution, especially in the ortho-position, enhanced the velocity of glucosyl conjugation. Ortho-hydroxyphenol (catechol) was also glucosylated with a higher velocity than phenol. These results suggest that the acidity of a phenolic hydroxyl group and position of a substituent can play important roles in the glucosylation of phenolic compounds by cultured cells of G. jasminoides.

Genetic nature of low capsaicin content in the variant strains induced by grafting in Capsicum annuum L.

SummaryThe genetic nature of low capsaicin content in variant strains induced by grafting was elucidated by crossing the G5S23 strain with the two cultivars, ‘Yatsubusa’ (Capsicum annuum L. var. fasciculatum Ilish) and ‘Spanish Paprika’ (C. annuum L. grossum Sendt) originally used for grafting. Decreased capsaicin synthesis was a stable characteristic for at least several generations from G5S16 to G5S23 and was transmitted to the progenies of crosses. This fact shows that the decreased capsaicin synthesis is a genetic trait in the graft-induced variant strains. The genetically dependent characteristic of pungency of the G5S23, ‘Yatsubusa’ and ‘Spanish Paprika’ were analysed by High Perfomance Liquid Chromatography measurement and tasting assay.Cross experiment between the G5S23 strain, hot parent ‘Yatsubusa’ and sweet parent ‘Spanish Paprika’ showed that ‘pungent’ and ‘sweet’ for pungency chracteristics are generally controlled by at least two pairs of genes. Although segregation of capsaicin content and pungency was clearly demonstrated in F2 progenies from reciprocal crosses between the G5S23 strain and ‘Spanish Paprika’, F2 progenies from reciprocal crosses between G5S23 and ‘Yatsubusa’ were all hot and did not develop low capsaicin plants.

Anthocyanin accumulation and changes in activities of phenylalanine ammonia-lyase and chalcone synthase in roselle (Hibiscus sabdariffa L.) callus cultures

Time-course changes in anthocyanin accumulation, phenylalanine ammonia-lyase activity and chalcone synthase activity were examined in roselle callus tissues incubated under different culture conditions. Phenylalanine ammonia-lyase activity was not affected by either the kind of auxin supplemented to the medium or light regime. In contrast, chalcone synthase activity was markedly suppressed when the callus was cultured with a medium containing indole-3-acetic acid instead of 2,4-dichlorophenoxyacetic acid (2,4-D) or in the dark. The results imply that in roselle callus cultures chalcone synthase plays a more important role in anthocyanin biosynthesis regulated by 2,4-D and light irradiation than phenylalanine ammonialyase.

CHARACTERIZATION OF GRAFT-INDUCED CHANGE IN CAPSAICIN CONTENT OF CAPSICUM ANNUUM L.

SummaryCapsaicin contents were measured in the progenies from the test crosses between the strain, G5S17 derived from fruit with the graft-induced change in fruit shape and the original two cultivars, Yatsubusa (Capsicum annuum L. var fasciculatumIlish) and Spanish Paprika (C. annuum L. var. grossumSendt) used for grafting.The strain, G5S17 contained a lower amount of capsaicin than the original pungent cultivar Yatsubusa used as scion. The characteristic of the lowered capsaicin content in the strain has been stably inherited through seed propagation, and has also been transmitted to the progenies from the crosses with the original two cultivars used for scion or stock. These features in the capsaicin content agreed with those in fruit shape in the graft-induced change.

Position-specific glucosylation of salicyl alcohol with an enzyme preparation from Gardenia jasminoides cultured cells

An enzyme activity catalyzing position-specific glucosylation of salicyl alcohol to form salicin was demonstrated in a partially purified enzyme preparation from cultured cells of Gardenia jasminoides. The reaction proceeded linearly with respect to time and protein concentration and had a pH optimum of 9.0 and a temperature optimum of 50°C. Normal Michaelis-Menten kinetics were observed for the substrates salicyl alcohol (Km = 0.53 mM) and UDP-glucose (0.64 mM). Formation of isosalicin was not detected with the present enzyme preparation. The new enzyme described here can be classified as UDP-glucose: salicyl alcohol phenyl-glucosyltransferase.

Studies on the Physiology and Ecology of Amaranthus viridis

アオビユ Amaranthus viridis の栽培および収穫時期を知る目的で, 4月と8月には種し, 栽培試験を行なった。また, Casamino acid の chlorophyll 含量に与える効果についても検討した。1. 生長量は4月播きが高く, 乾葉重においては8月播きの3倍以上であった。2. Chlorophyll の含量は4月播き, 8月播きともに乾葉重との間に逆相関関係があった。3. Chloryphyll 含量は, 4月播きでは6月末から7月始めにかけて高く, 最高値1.46%, 8月播きでは9月中旬から10月末に高く, 最高値1.41%であった。4. Chlorophyll 収量は, 4月播きで6月末から7月末の間に多く, 最高値は8月播きのそれの2.5倍以上であった。5. Casamino acid 2,000ppmは chlorophyll b の含量を高めたが, 生長および chlorophyll a には効果がなかった。