Light-induced Synthesis of Anthocyanin in Carrot Cells in Suspension: II EFFECTS OF LIGHT AND 2, 4-D ON INDUCTION AND REDUCTION OF ENZYME ACTIVITIES RELATED TO ANTHOCYANIN SYNTHESIS

Time-courses of light-induced activities of enzymes relatingto anthocyanin formation were studied. Phenylalanine ammonia-lyase(PAL), 4-cumarate CoA ligase (4CL) and cinnamate-4-hydroxylase(C4H) (group 1 enzymes) and chalcone synthase (CHS) and chalcone-flavanoneisomerase (CHFI) (group 2 enzymes), were studied in carrot suspensioncells which were irradiated 5 d after transfer to a 2,4-dichlorophenoxyaceticacid (2,4-D)-free medium in the dark. Time-courses of group1 enzymes showed two peaks (fast and slow) with the slow peakincreasing almost parallel to anthocyanin accumulation. Time-coursesof group 2 enzymes showed one peak corresponding to the slowpeak of group 1. From the inhibitor experiment, the fast peakalso corresponded to the activity of the newly synthesized enzyme.From the initial phase of the time-courses, enzymes belongingto group 1 always induced more rapidly than those of group 2,and their induction was co-operative. However, once anthocyanin synthesis was induced by light, neitheraddition of 2,4-D nor transfer to darkness could prohibit anthocyaninsynthesis completely. Addition of 2,4-D in the dark completelysuppressed anthocyanin synthesis within 1 d and the activityof CHS also disappeared within 1 d. These results are explainedby a previous hypothesis (Takeda, 1988) that 2,4-D induces thestate change of cells. Key words: Anthocyanin, co-ordinate induction, Daucus carota, 2,4-dichlorophenoxyacetic acid, light-triggered     

Regulation of phenylalanine ammonia-lyase genes in carrot suspension cultured cells

Induction of anthocyanin synthesis occurs during metabolic differentiation in carrot suspension cultured cells grown in medium lacking 2,4-dichlorophenoxyacetic acid (2,4-D), and is closely correlated with embryogenesis. Anthocyanin synthesis may also be induced by light-irradiation under different culture conditions. The phenylalanine ammonia-lyase (PAL) gene (TRN-PAL), which was transiently induced by the transfer effect, was also rapidly induced after light-irradiation. However, TRN-PAL was not involved in anthocyanin synthesis. A second PAL gene, ANT-PAL, was involved in anthocyanin synthesis. ANT-PAL was induced during metabolic differentiation in medium lacking 2,4-D parallel with the induction of chalcone synthase (CHS). PAL genes in the carrot genome are expressed differentially depending on the nature of the environmental stimulus, e.g. transfer effect and light, and other parameters which also affect anthocyanin synthesis.Abbreviations CHS chalcone synthase - 2,4-D 2,4-dichlorophenoxyacetic acid - GUS -glucuronidase - Luc firefly luciferase - PAL phenylalanine ammonia-lyase - UV ultraviolet     

Changes in Activities of Enzymes Involved in General Phenylpropanoid Metabolism during the Induction and Reduction of Anthocyanin Synthesis in a Carrot Suspension Culture as Regulated by 2,4-D

The activities of enzymes involved in general phenylpropanoidmetabolism were followed in a carrot suspension culture duringthe induction and reduction of anthocyanin synthesis regulatedby 2,4-D. When no anthocyanin synthesis occurred in a mediumcontaining 2,4-D (+2,4-D medium), the activities of phenylalanineammonia-lyase (PAL) and 4-coumarate:CoA ligase (4CL) increased1 day after transfer due to the transfer effect, but subsequentlydecreased and remained at a low level. Cinnamate-4-hydroxylase(C4H) activity showed a low level throughout culture. When cellswere transferred to a medium lacking 2,4-D (–2,4-D medium),the activities of PAL, C4H and 4CL increased and maximum activitiesof these enzymes were observed 6–7 days after transfer,when anthocyanin was most rapidly synthesized. When cells were cultured in the –2,4-D medium, the additionof 2,4-D immediately reduced the induced activity of PAL. PALactivity was super-induced by the transfer effect, while anthocyaninsynthesis decreased. The addition of intermediates of generalphenylpropanoid metabolism, with 2,4-D, to the medium 6 daysafter transfer to the –2,4-D medium did not promote anthocyaninsynthesis, whereas dihydroquercetin did promote it. Regulationof anthocyanin synthesis by 2,4-D is discussed in relation tochanges in enzyme activities involved in general phenylpropanoidmetabolism. ¹ Present address: Cell Science and Technology Division, FermentationResearch Institute, Agency of Industrial Science and Technology,Yatabe-machi, Ibaraki 305, Japan. ² Present address: Biological Institute, Faculty of Science,Tohoku University, Sendai 980, Japan.     

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.Abbreviations LS Linsmaier and Skoog - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - PAL phenylalanine ammonia-lyase - CHS chalcone synthase     

Regulatory mechanisms of biosynthesis of betacyanin and anthocyanin in relation to cell division activity in suspension cultures

Regulatory mechanisms of betacyanin biosynthesis in suspension cultures of Phytolacca americana and anthocyanin in Vitis sp. were investigated in relation to cell division activity.Betacyanin biosynthesis in Phytolacca cells clearly shows a positive correlation with cell division, as the peak of betacyanin accumulation was observed at the log phase of batch cultures. Incorporation of radioactivity from labelled tyrosine into betacyanin also showed a peak at early log phase. Aphidicolin, an inhibitor of DNA synthesis, and propyzamide, an antimicrotubule drug, reduced betacyanin accumulation and inhibited the incorporation of radioactivity from labelled tyrosine into betacyanin at concentrations which were inhibitory to cell division. Both inhibitors reduced the incorporation of radioactivity from labelled tyrosine to 3,4-dihydroxyphenylalanine (DOPA), but the incorporation of labelled DOPA into betacyanin was not affected. These results suggest that the conversion of tyrosine to DOPA is coupled with cell division activity.In contrast, the anthocyanin accumulation in Vitis cells showed a negative correlation with cell division. Accumulation occurred at the stationary phase in batch cultures when cell division ceased. Aphidicolin or reduced phosphate concentration induced a substantial increase in anthocyanin accumulation as well as the inhibition of cell division. Chalcone synthase (CHS) activity increased at the time of anthocyanin accumulation. Northern blotting analysis indicated that changes in CHS mRNA levels corresponded to similar changes in enzymatic activity. The pool size of endogenous phenylalanine was low during active cell division, but increased before anthocyanin began to accumulate and concomitantly with increasing levels of CHS mRNA. Exogenous supply of phenylalanine at the time of low endogenous levels induced the elevation of CHS mRNA and anthocyanin accumulation. These results indicate that the elevation of endogenous phenylalanine levels, when cell division ceases, may cause the increase in CHS mRNA levels, resulting in increased CHS activity and subsequently in anthocyanin accumulation in Vitis suspension cultures.Abbreviations CHS chalcone synthase - CHFI chalcone flavanone isomerase - DOPA 3,4-dihydroxyphenylalanine - PAL phenylalanine ammonia lyase     

Pisatin metabolism in pea (Pisum sativum L.) cell suspension cultures

Cell suspension cultures were established from germinating pea (Pisum sativum L.) seeds. This cell culture, which accumulated pisatin, consisted mostly of single cells containing a few cell aggregates. The cells responded to treatment with a yeast glucan preparation with transient accumulation of pisatin in both cells and culture media. Addition of pisatin to cell cultures resulted in increased synthesis of pisatin. Phenylalanine ammonia-lyase, chalcone synthase and isoflavone reductase activities were present in untreated cells. Upon treatment with an elicitor preparation the activities of the first two enzymes showed a rapid, transient increase up to 20 hours after treatment. Isoflavone reductase showed a major and minor peak at 16 and 36 h, respectively, after elicitor treatment. The time course of the enzyme activity and pisatin accumulation is consistent with an elicitor-mediated response.Abbreviations CHS chalcone synthase - 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indole-3-butyric acid - IFR isoflavone reductase - 2iP 6-(dimethylallylamino)-purine - MS Murashige & Skoog basal salt medium - PAL phenylalanine ammonia-lyase - PMSF phenylmethylsulfonyl fluoride - POPOP 1,4-bis-2-(4-methyl-5-phenyloxazolyl)-benzene - PPO 2,5-diphenyloxazole     

Differential regulation of phenylalanine ammonia-lyase genes during anthocyanin synthesis and by transfer effect in carrot cell suspension cultures

Phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) catalyses the first step in the phenylpropanoid pathway and is induced during differentiation and by various stimuli. In carrot ( Daucus carota L. cv. Kurodagasun) suspension culture cells, PAL is slowly induced during anthocyanin synthesis which occurs in a medium lacking 2,4-dichlo-rophenoxyacetic acid and is also induced rapidly and transiently by transferring and diluting cells to fresh medium. Analyses of nucleotide sequences derived from PAL cDNAs revealed that the PAL mRNAs induced by transfer were transcribed from different carrot PAL genes than the PAL mRNAs induced during anthocyanin synthesis. Northern blotting using probes derived from 3'non-coding regions for PAL cDNAs confirmed that different PAL genes were induced during anthocyanin synthesis and after transfer. Induction of different PAL genes occurs in response to differences in the induction trigger.     

Effects of inoculum density,zeatin and sucrose on anthocyanin accumulation in a carrot suspension culture

Anthocyanin formation in a suspension culture of Daucus carota is induced by transfer from medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) to one lacking 2,4-D. The specific yields were strongly influenced by the inoculum density. Inoculum density altered the effect of zeatin concentration on anthocyanin accumulation. The in part by increasing the sucrose levels. It was inferred from the results that sucrose was exhausted at a low concentration of sucrose and at a high cell density, resulting in the decrease of yield of anthocyanin.     

The effect of hormones on anthocyanin accumulation in cell cultures of Haplopappus gracilis

Summary Suspension cultures of Haplopappus gracilis accumulated anthocyanin when grown in defined media with 4.5×10^-6M 2,4-D. Transfer of cells to media with 10^-5M kinetin or benzyladenine and no auxin or 10^-7M NAA for 6 days resulted in increased anthocyanin concentration of the cells but the total amount of pigment was unaffected due to differences in growth rates. The cultures yielded up to 35 mg pigment per gram dry weight.Cells grown in batch culture in media with 10^-5M kinetin and with 10^-7 M NAA or 5×10^-5M NAA sampled and analyzed daily grew at the same rate. The concentration of anthocyanin differed, being lower in cells at 5×10^-5M NAA. After 6 days there was a rapid increase in pigment formation, and by 14 days the concentration of anthocyanin in cells in the two media were the same.When the cells were cultured in 3.5-1 phytostats and 600 ml culture was replaced daily with 600 ml medium, anthocyanins accumulated when the NAA concentration was 10^-7M but not at 10^-6M. At 10^-7M NAA the cultures remained pigmented and anthocyanin accumulation could be restored after a temporary loss of pigmentation due to an earlier, higher auxin concentration. The changes in concentration of phenylalanine ammonia-lyase did not correspond to changes in the rate of anthocyanin accumulation. The enzyme showed a maximum 4–8 h after inoculation of cells to fresh media. Cells grown on agar plates and rich in anthocyanin were observed to divide without loss of pigmentation, demonstrating that cells differentiated with respect to anthocyanin production undergo mitosis.Issued as NRCC No. 11388.Abbreviations used: 2,4-D=2,4-dichlorophenoxyacetic acid, NAA + -naphthaleneacetic acid.     

Changes in the phenolic metabolism of suspension cultures of Acer pseudoplatanus L. Caused by the addition of 2-(chloroethyl)phosphonic acid (CEPA)

Summary 2-(Chloroethyl)phosphonic acid (CEPA) inhibited the rise in tannin production and phenylalanine ammonia-lyase EC 4.1.1.5 (PAL) activity shown by Acer cells in media containing 9.0×10^–7 M 2,4-D for a period of 2–3 days after its addtion.Abbreviation 2,4-D 2,4-dichlorophenoxyacetic acid     

Induction of anthocyanin synthesis in relation to embryogenesis in a carrot suspension culture: Correlation of metabolic differentiation with morphological differentiation

A system in which anthocyanin synthesis could be induced under a defined condition, was established in a carrot suspension culture. A cell suspension culture of carrot ( Daucus carota L. cv. Kurodagosun) was subcultured for more than a year in a medium containing 5 × 10⁻⁷ M 2,4-dichlorophenoxyacetic acid (2,4-D). At every subculture the cultures were sieved through nylon screens and the cells and cell clusters collected in the size range of 31–81 μm were transferred to a fresh medium. When the cells were transferred to a medium without auxin, synthesis of anthocyanin was induced. Zeatin promoted anthocyanin synthesis in a medium lacking auxin, with maximum yields of anthocyanin obtained at 10⁻⁷ to 10⁻⁸ M zeatin, 2,4-D at higher concentrations than 10⁻⁷ M inhibited anthocyanin synthesis completely. The sieved cells were fractionated by Ficoll density gradient centrifugation. Somatic embryos were formed in the fraction of higher density (>14% of Ficoll) in a medium containing 10⁻⁷ M zeatin but lacking auxin, while synthesis of anthocyanin was hardly observed. On the other hand, cells in the fraction of lower density (<12% of Ficoll) synthesized anthocyanin in the same medium, but formed few embryos. Forty to fifty percent of the total cells in this lighter cell fraction synthesized anthocyanin at a maximum. The similarity between anthocyanin synthesis and embryogenesis was observed in the time course as well as in the effects of growth regulators. The correlation between metabolic and morphological differentiation is discussed.     

Activities of enzymes involved in the phenylpropanoid pathway in constitutively salicylic acid-producing tobacco plants

Chorismate mutase (CM, EC 5.4.99.5), phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and chalcone synthase (CHS, EC 2.3.1.74) activities were studied in constitutive salicylic acid-producing (CSA) tobacco plants in relation to the accumulation of flavonoids and chlorogenic acid. The CM, PAL and CHS activities in CSA-tobacco (Nicotiana tabacum cv. Samsun NN) plants were lower than in non-transgenic tobacco plants. Flavonoid and chlorogenic acid accumulation was suppressed in CSA-tobacco plants compared to those of non-transgenic tobacco plants.