Flowering Of Pharbitis Nil Research Articles

33.アサガオとシソのストレス応答花成の制御機構(口頭発表)

33.アサガオとシソのストレス応答花成の制御機構(口頭発表)

The involvement of gibberellins in phytochrome-controlled flowering of Pharbitis nil

The seedlings of <em>Pharbitis nil</em>, a sesitive short-day plant (SDP), were cultivated under special photoperiodic conditions: 72-h-long darkness, 24-h-long white light with low intensity, 24-h-long inductive night. During 24-h-long inductive darkness the total content of gibberellins in cotyledons underwent fluctuations with a maximum at 0 h and 8 h, and a decrease at the end of the dark period. FR light applied at the end of the 24-h-long white-light period inhibited flowering. R light flash and partially exogenous GA3 added on cotyledons could reverse the effect of FR. The seedling growth was not affected by FR and R light irradiation, but was promoted by exogenous GA3 application. The obtained results suggest that gibberellins are involved in photoperiodic control of SDP <em>P. nil</em> flowering. This involvement has nothing in common with participation of gibberellins in the control of the elongation growth of seedlings.

91. Poor nutrition stress-induced flowering in Pharbitis nil is regulated by salicylic acid and auxin

91. Poor nutrition stress-induced flowering in Pharbitis nil is regulated by salicylic acid and auxin

The influence of light and the place of its perception on the flowering of Pharbitis nil.

The estimation of participation and density of forage species in several xerothermic communities of the Lublin Upland were carried out in 2004 and 2005. Most plants species visited by bees are grouped in plots of the <i>Brachypodio</i>-<i>Teucrietum</i> and the <i>Adonido</i>-<i>Brachypodietum pinnati</i> communities. The nectariferous and polleniferous taxons are mostly perennials predominated by hemicryptophytes (79%), others are terophytes and geophytes (21%). Successive blooming of the nectariferous and polleniferous species in both associations ensures unbroken food flow from the early spring until the late summer and early autumn. Xerothermic swards make a valuable food potential to be important for the <i>Apoidea</i> before and after blooming of the main forage cultivated crops.

Constitutive expression of the GIGANTEA Ortholog Affects Circadian Rhythms and Suppresses One-shot Induction of Flowering in Pharbitis nil, a Typical Short-day Plant

GIGANTEA (GI) is a key regulator of flowering time, which is closely related to the circadian clock function in Arabidopsis. Mutations in the GI gene cause photoperiod-insensitive flowering and altered circadian rhythms. We isolated the GI ortholog PnGI from Pharbitis (Ipomoea) nil, an absolute short-day (SD) plant. PnGI mRNA expression showed diurnal rhythms that peaked at dusk under SD and long-day (LD) conditions, and also showed robust circadian rhythms under continuous dark (DD) and continuous light (LL) conditions. Short irradiation with red light during the flower-inductive dark period did not change PnGI expression levels, suggesting that such a night break does not abolish flowering by affecting the expression of PnGI. In Pharbitis, although a single dusk signal is sufficient to induce expression of the ortholog of FLOWERING LOCUS T (PnFT1), PnGI mRNA expression was not reset by single lights-off signals. Constitutive expression of PnGI (PnGI-OX) in transgenic plants altered period length in leaf-movement rhythms under LL and affected circadian rhythms of PnFT mRNA expression under DD. PnGI-OX plants formed fewer flower buds than the wild type when one-shot darkness was given. In PnGI-OX plants, expression of PnFT1 was down-regulated, suggesting that PnGI functions as a suppressor of flowering, possibly in part through down-regulation of PnFT1.

39. Analyses of endogenous salicylic acid and the flowering gene PnFT which regulate stress-induced flowering in Pharbitis nil

39. Analyses of endogenous salicylic acid and the flowering gene PnFT which regulate stress-induced flowering in Pharbitis nil

Metabolism of α-ketol derivative of linolenic acid (KODA), a flowering-related compound, in Pharbitis nil

α-Ketol of octadecadienoic acid (KODA, 1) has been suggested to play a role in the photoperiod-regulated flowering in Pharbitis nil. The level of 1 in cotyledons is temporarily controlled during short-day conditions. The biosynthesis of 1 is well studied in plants; however, its in vivo conversion is less understood. We have investigated this issue by studying the metabolism of exogenously-applied [U- 13C]- 1, [1- 14C]- 1, and non-labeled 1 in P. nil seedlings by the spectroscopic methods and identified six major metabolites ( 4– 9). We have also found that the enantiomers of 1 are differentially metabolized in P. nil seedlings.

Spectral Sensitivity of the Promotion and Inhibition of Flowering in Morning Glory (Pharbitis nil)

Seedlings of morning glory (Pharbitis nil) were exposed to blue light-emitting diodes (LEDs) with various peak wavelengths, or mixture lights of blue light and red light to confirm the spectral sensitivity to flowering. Flowering responses to the respective LEDs corresponded to the absorption spectrum of cryptochromes, which is one of blue light receptors. On the other hand, the light qualities consisting of rich blue light had an effective influence on flowering responses. The number of flower buds decreased after being exposed to the red-rich light qualities, a situation under which phytochromes absorb well. From our study, we conclude that cryptochromes, which absorb blue light, effectively act on flowering, whereas phytochromes act on the inhibition of flowering in Pharbitis nil under the normal light/dark cycles.

Inhibitory role of gibberellins in theobroxide-induced flowering of Pharbitis nil

Theobroxide, a novel active compound isolated from a fungus, has been reported previously to induce potato tuberization and flower bud formation in Pharbitis nil under non-inductive long-day conditions. Up to date, the action mechanism of theobroxide on flower-bud induction of P. nil, however, is still unknown. In the present study, we observed a reduction of the stem length, along with the induction of flower buds, in theobroxide-treated and short-day-grown P. nil plants. Also, the results showed that flower bud formation was delayed markedly in P. nil seedlings with removal of cotyledons or exposure to night break. The suppression effect of night-break and cotyledon-removal, however, was abolished completely by spraying theobroxide. Endogenous gibberellin(1/3) contents in P. nil plants treated with theobroxide or grown under short-day conditions were relatively lower, suggesting that gibberellins probably are negatively involved in theobroxide- and short-day-induced flower-bud formation of P. nil.

17. Involvement of salicylic acid in the stress-responding flowering in Pharbitis nil

17. Involvement of salicylic acid in the stress-responding flowering in Pharbitis nil

The Effect of Various Lipids on Flowering of Pharbitis nil in in vitro Culture

The effect of applied arachidonic acid, prostaglandin (PGE1) and various sterols and combinations of arachidonic acid + sterols, on flowering of Pharbitis nil were ascertained by using a tissue culture technique. It was found that arachidonic acid, PGE1 stigmasterol, testosterone, cholesterol, stigmasterol + arachidonic acid, β-sitosterol + arachidonic acid and cholesterol + arachidonic acid all caused earlier flowering. Four inhibitors of prostaglandin biosynthesis (gentisic acid, acetylsalicylic acid, salicylic acid and oleic acid), inhibited flowering completely. The results confirm that the compounds tested could possibly play a role in the flowering of P. nil.

Characterization of transcriptional oscillation of an Arabidopsis homolog of PnC401 related to photoperiodic induction of flowering in Pharbitis nil.

AtC401 is an Arabidopsis homolog of PnC401 that is related to photoperiodic induction of flowering in Pharbitis nil. These genes show free-running rhythms. To study the free-running rhythm of AtC401, we fused a firefly luciferase reporter to the AtC401 promoter and transformed it into Arabidopsis plants. The observed bioluminescence oscillated under continuous light and continuous dark only with sucrose supplementation. The free-running period of bioluminescence was temperature-compensated between 22 degrees C and 30 degrees C. Light-pulse experiments under continuous darkness produced a phase-response curve typical of circadian rhythms. We conclude that rhythmic expression of AtC401 is controlled by a circadian oscillator.

The processes inhibited and promoted by abscisic acid in photoperiodic flowering of Pharbitis nil

Summary A dual role of abscisic acid (ABA) in photoperiodic flowering of Pharbitis nil , cv. Violet was studied. ABA given before an inductive dark treatment lowered the flowering response without influencing the critical night length and the most effective time of a night break. ABA given after a dark treatment accelerated the transport of flowering stimulus and enhanced flower initiation response at shoot apex. Endogenous ABA level in cotyledons was determined by gas chromatography-selected ion monitoring. There was no remarkable difference between ABA levels under short-day and long-day conditions. Fluridone, an inhibitor of ABA biosynthesis, given before and during an inductive dark treatment affected flowering response only slightly. The results indicate that exogenous ABA inhibits the early phase of the flowering without influencing the time-measuring process, and promotes both transport of the flowering stimulus and flower-initiation process, although endogenous ABA plays little role in the regulation of flowering.

Effects of the Inhibitors of Biosynthesis and Degradation of Catecholamines on Photoperiodic Induction of Flowering in Pharbitis nil

The effects of the inhibitors of biosynthesis and degradation of catecholamines (CA) on photoperiodic induction of flowering were examined in Pharbitis nil , a short-day plant. The inhibitors of CA biosynthesis such as iodotyrosine, methyldopa, methyltyrosine, carbidopa, NSD-1015, and 6-hydroxydopamine inhibited floral initiation when applied before and during a dark period but not after dark treatment, suggesting that these compounds inhibited the production of a flowering hormone in cotyledons. Inhibitors of CA degradation such as SK&F525A, amitriptyline, pargyline, gallic acid, n-butyl gallate, OR-486 and Ro-41-0960 also inhibited flowering, and these inhibitors were effective even when applied after dark treatment, although they did not inhibit floral initiation when applied at 48 h after the end of dark treatment. This result suggested that the inhibitors of CA acted in bud and inhibited the expression of flowering hormone in bud, or the transformation of it into an active substance. The inhibitors used in the present experiment inhibited flowering without the inhibition of vegetative growth. Exogeneous noradrenaline did not induce floral initation under continuous light but partially reversed the inhibitory effect of 6-hydroxydopamine.

Biochemistry of Short-Day and Long-Day Flowering in Pharbitis nil.

Pharbitis nil has been widely used as a typical short-day plant in studies of flowering. It can be induced to flower by a single dark treatment even in seedling with just unfolded cotyledons. This plant is also capable of inducing to flower under continuous light by giving various treatments such as poor nutrition (PN), high-intensity light (HL), low-temperature (LT) and physical or chemical inhibition of root elongation etc. Furthermore, the responses to these treatments were different among strains. Therefore, it is a suitable experimental material to study the mechanism of floral induction. We are investigating to elucidate the mechanism of floral induction under various conditions by using Pharbitis nil, strain Violet, Kidachi and Tendan. In this symposium, we will report two subjects on flowering in Pharbitis nil, (1) the mechanism of floral induction of long-day (LD) flowering by PN, HL and LT, (2) our recent works on short-day flowering. Pharbitis nil, strain Violet, is induced to flower under continuous light by PN, HL and LT, but strains Kidachi and Tendan were not by PN and HL, though they initiated floral buds under LT. HL has interesting effects on flowering, that is, (1) induction, (2) promotion of LT flowering, (3) inhibition of short-day flowering. The cotyledons are necessary for flowering under these conditions. Therefore, we widely analyzed the extracts from the cotyledons by using HPLC equipped with various detectors. As the results, we found several substances which closely correlated with flowering. Floral induction under PN and HL is closely correlated with the accumulation of some phenylpropanoids such as chlorogenic acid (CGA), p-coumaroylquinic acid (CQA) and pinoresinol-β-D-glucoside (PRG), sugars such as glucose, fructose and sucrose, and polyamine such as putrescine (PUT). Under LT, feruloylquinic acid (FQA) and ascorbic acid instead of CGA and PRG increased preceding floral initiation. Promotive and inhibitory effects of HL on flowering can be explained by the action of ascorbic acid. High level of sugars is necessary condition and the accumulation of CGA, PRG, FQA and/or PUT seems to be sufficient condition, that is, floral initiation under long-day condition always occurred when necessary-sufficient condition was fulfilled. In order to elucidate the physiological roles of these phenyl-propanoids, we remarked PRG, which is known as an inhibitor of phospho-diesterase (PDE). Inhibitors of PDE such as papaverine, theophyline and caffeine promoted flowering under PN. Moreover, FQ and some benzoic acid derivatives which promoted LD flowering inhibited the activity of PDE, suggesting the involvement of c-AMP in LD flowering. It will be described about the endogenous level of c-AMP in relation to PN flowering. In pattern analysis by using HPLC, it was difficult to find out florigen-like substance in extracts from photoperiodically induced leaves. Recently, we found that the inhibitors of biosynthesis and degradation of catecholamines (CA) inhibited floral initiation when they were applied before and during the dark period. Thus, we introduced a coulometric array system (ESA-Coulochem), which can measure CA at f mol level, for the quantitative measurement of CA. Unexpectedly we failed to detect CA, but we found many substances which seem to be florigen. It will be referred to their results.

Influences of plant hormones on photoperiodic flowering in Pharbitis nil: re-evaluation by the perfusion technique

Influences of plant hormones on photoperiodic flowering in Pharbitis nil, var. Violet was re-evaluated by assaying them with a newly developed perfusion technique which can directly treat mesophyll cells with sample solution. Gibberellin A3 promoted the flowering response and indole-3-acetic acid, trans-zeatin and abscisic acid inhibited it when they were perfused immediately before an inductive dark treatment. The promotion or inhibition of flowering was not or hardly observed when solutions containing these plant hormones were applied by the dropping method to surface of cotyledons or plumules of the assay plants. The detection of clear flower-promoting and -inhibiting effects of the plant hormones may be due to the improved efficiency of incorporation of applied substances into plant tissue in the perfusion technique.

Abscisic acid both promotes and inhibits photoperiodic flowering of Pharbitis nil

Abscisic acid both promotes and inhibits photoperiodic flowering of Pharbitis nil

39 Involvement of Endogenous IAA and ABA in the Flowering of Pharbitis nil

39 Involvement of Endogenous IAA and ABA in the Flowering of Pharbitis nil

Genes for dwarfing and photoperiod flowering response inPharbitis nil choisy

Dwarfing and sensitivity to the duration of a single inductive dark period for flowering ofPharbitis nil in F2 progeny of a cross between the tall strain Tendan, and the dwarf, Kidachi appear to be controlled by the alleles at two independent loci. Progeny of a similar cross between the tall strain Violet and the dwarf Kidachi at F2 and F3 also showed single locus segregation for tall: dwarf plants. In this cross, differences in photoperiodic response could be identified in F3 families but they were not simply inherited. There was some evidence of difficulties with classification of the F2 plants, but also, the flowering of the F1 between the two less sensitive strains Tendan and Violet indicated complex inheritance of their photoperiodic response. Complementary dominant alleles at three independent loci may be necessary for flowering in even shorter dark periods with the sensitive strain Kidachi.

Structure and Expression of a Heat-Shock Protein 83 Gene of Pharbitis nil

Four cDNA clones representing mRNAs whose levels were affected by a photoperiod that induces flowering in Pharbitis nil were isolated by a differential hybridization screening procedure. The level of mRNAs represented by three clones (12L, 15L, and 17L) increased following a photoperiod that induces flowering and that represented by the fourth clone (clone 27) increased under conditions in which flowering was inhibited. DNA sequence analysis showed that one cDNA, clone 17L, is homologous to members of the 83- to 90-kD heat-shock protein (hsp) gene family. The corresponding gene, hsp83A, was isolated and its DNA sequence was determined. hsp83A encodes a protein that exhibits 70% amino acid identity with Drosophila melanogaster HSP83. The P. nil hsp83A gene contains two introns within the coding region. hsp83A mRNA was not detectable in cotyledons of plants grown in continuous light, but its level increased transiently following a 14-h dark period and reached a maximum 2 h after the lights were turned on. A dramatic increase in the level of hsp83A mRNA was also found 2 h after an end-of-day dark treatment. Genomic Southern blot analysis demonstrated that the P. nil hsp83-90 gene family consists of at least six members, one of which appears to be constitutively expressed in the light.