POST-POLLINATION PHENOMENA IN ORCHID FLOWERS. VII. PHOSPHATE MOVEMENT AMONG FLORAL SEGMENTS

Radioactive phosphate applied to labella (lips, median petals), dorsal (median) sepals or stigmas of Cymbidium cv Jungfrau is transported to all parts of the flower. Transport levels vary depending on the sites of application or accumulation. Pollination or application of NAA to the stigma cause accumulation of ³²P in gynostemia (columns) and ovaries. Translocation characteristics correlate with vascular anatomy of Cymbidium flowers.     

POST-POLLINATION PHENOMENA IN ORCHID FLOWERS. VI. EXCISED FLORAL SEGMENTS OF CYMBIDIUM

Whole Cymbidium Sw. (Orchidaceae) flowers, ones with their labella, gynostemia or perianth removed as well as excised ovaries, lips and columns, were pollinated, emasculated and treated with NAA and maintained in media containing or lacking NAA. The results indicate that, 1) the rostellar-stigmatic region seems to control many post-pollination phenomena, 2) auxin from the medium apparently does not reach the rostellum and/or stigma, 3) there is a certain interdependence among floral segments which exhibit post-pollination phenomena, and 4) once initiated, these phenomena may be subject to localized effects. These findings are taken as an indication that pollinated orchid flowers are a well-integrated system despite the diversity and number of observable phenomena.     

Effects of Methyl Jasmonate on Anthocyanin Accumulation, Ethylene Production, and CO2 Evolution in Uncooled and Cooled Tulip Bulbs

Effects of methyl jasmonate (JA-Me) on anthocyanin accumulation, ethylene production, and CO₂ evolution in uncooled and cooled tulips (Tulipa gesneriana L. cvs. Apeldoorn and Gudoshnik) were studied. JA-Me stimulated anthocyanin accumulation in stems and leaves from uncooled and cooled bulbs of both cultivars. The highest level of anthocyanin accumulation was observed in leaves from cooled bulbs treated with 200 μL/liter JA-Me. In sprouting bulbs treated with 100 μL/liter and higher concentrations of JA-Me, the ethylene production began to increase at 3 days after treatment, being extremely greater in uncooled bulbs than in cooled ones. JA-Me also stimulated CO₂ evolution in both cultivars, depending on its concentrations. CO₂ evolution in sprouting bulbs was not affected by cooling treatment. These results suggest that anthocyanin accumulation by JA-Me in tulip leaves is not related to ethylene production stimulated by JA-Me. Received October 10, 1997; accepted November 17, 1997     

Methyl Jasmonate Induces Gums and Stimulates Anthocyanin Accumulation in Peach Shoots

The effect of methyl jasmonate (JA-Me) on the induction of gum was studied in relation to the action of ethylene in peach (Prunus persica Batsch cv. Benishimizu) shoots. JA-Me applied at concentrations of 0.1–2.5% (w/w) in lanolin paste to current growing or older shoots substantially induced gums 3 days after treatment. The amount of gums exuded increased depending on the dose of JA-Me. Ethephon (2-chloroethyl- phosphonic acid) at 1 or 2% (w/w) in lanolin induced gum and strongly enhanced the promoting effect of JA-Me on gum formation. JA-Me also induced anthocyanin accumulation in current growing shoots, but ethephon did not. Anthocyanin accumulation in response to JA-Me at a concentration of 10 mg/liter or higher was observed also in the cut shoots of peach. Ethephon (100 mg/liter) substantially inhibited anthocyanin accumulation induced by JA-Me. These facts suggest that JA-Me plays an important role in gum formation as well as ethylene and in anthocyanin accumulation and that these processes are not necessarily accompanied by each other in peach shoots. Received January 26, 1998; accepted March 4, 1998     

POSTPOLLINATION PHENOMENA IN ORCHID FLOWERS. V. PARTICIPATION BY THE ROSTELLUM AND GYNOSTEMIUM TIP

Removal of the rostellum following pollination does not prevent stigmatic closure in Cymbidium flowers and has a minimal effect on straightening of the gynostemium (column). However, this treatment does depress anthocyanin levels in both gynostemia and labella. Excision of the rostellum 30 or 60 min after pollination has a more pronounced effect than removal after 150 min. Stigmatic closure is not inhibited by removal of the gynostemium tip, but column swelling is reduced. These findings are discussed relative to rostellar functions and theories regarding their origin.     

Influence of putrescine on anthocyanin production in callus cultures of <Emphasis Type="Italic">Daucus carota</Emphasis> mediated through calcium ATPase

The influence of Putrescine (Put) on the growth and elicitation of anthocyanin in callus cultures of Daucus carota var. Nantes scarlet was investigated through the use of α-DL-difluoromethylarginine (DFMA), the polyamine (PA) biosynthetic inhibitor. It was observed that the addition of Put (0.05 mM) resulted in enhancement of growth and anthocyanin content. The anthocyanin content was found to be enhanced by 1.68 fold on the 21^st day as compared to the untreated controls. The PA inhibitor was found to result in lowering of the growth and the anthocyanin accumulation, which could be partially restored by the addition of Put in combination with this inhibitor. The levels of Ca²⁺ ATPase were also found to be elevated in treatment with Put suggesting the involvement of calcium in the elicitation of anthocyanin. The endogenous titres of PAs and the ethylene production under these treatments were also studied. The treatment with DFMA resulted in lower levels of endogenous PAs and higher levels of ethylene. Lowering of ethylene by putrescine treatment shows that PA treatment also inhibited ethylene formation, which would also imply that endogenous ethylene does not influence anthocyanin production in carrot callus cultures.     

EXPERIMENTAL CONTROL OF FLOWERING IN LEMNA. IV. INHIBITION OF PHOTOPERIODIC SENSITIVITY BY COPPER

Hillman , William S. (Brookhaven Nat'l. Lab., Upton, N. Y.) Experimental control of flowering in Lemna. IV. Inhibition of photoperiodic sensitivity by copper. Amer. Jour. Bot. 49(8): 892–897. Illus. 1962.—Lemna perpusilla 6746 and L. gibba G3 are both photoperiodi c in a purified Hoaglandtype medium; purification thus imitates the effects of high levels of chelating agents previously reported. On the addition of 0.5–10.0μM/liter cupric ion (optimum about 2.0μM/liter) L. perpusilla, instead of responding as a short-day plant, flowers in both long and short days, while L. gibba, formerly a long-day plant, loses its ability to flower. A similar, but less distinct, effect of Hg can be attributed to a “copper-sparing” action. No other ion tested, including Cd, Co, Cr, Mn, Ni, Pb or Zn, had a similar effect. Certain macronutrient ions, probably Ca and phosphate, modify but do not obscure the effects of copper. The action of copper can be interpreted as an inhibition of photoperiodic sensitivity, since it makes both plants respond as if under short days regardless of the actual conditions. Some possible mechanisms, including disturbance of the photoperiodic pigment system, are discussed.     

Elicitation of anthocyanin production in callus cultures of <Emphasis Type="Italic">Daucus carota</Emphasis> and the involvement of methyl jasmonate and salicylic acid

The effect of methyl jasmonate (MeJA) and salicylic acid (SA) on the anthocyanin accumulation, endogenous titres of polyamines and ethylene production in callus cultures of Daucus carota were studied. The interaction of these signaling molecules with elicitors from Aspergillus niger was investigated and the involvement of MeJA was elucidated through the use of the jasmonic acid (JA) biosynthetic inhibitor ibuprofen. MeJA and SA were both found to stimulate the anthocyanin production in the callus cultures. The highest levels of anthocyanin was observed in the cultures treated with 200 μM SA 0.36 % and 0.01 μM MeJA 0.37 %. The MeJA and SA treatments were also found to result in higher activity of Ca²⁺ ATPase suggesting that the enhancement of anthocyanin by SA and MeJA could be mediated through the involvement of the calcium channel. The treatment of the callus cultures with SA was found to result in marginally higher titres of endogenous polyamines (PAs) whereas MeJA resulted in lower levels of PAs as compared to the control. The SA treatment was found to result in lower ethylene production and the treatment with MeJA stimulated the ethylene production. These results suggest that the stimulation of anthocyanin production by MeJA and SA in callus cultures of D. carota is not related to the ethylene production.     

Arabidopsis ROOT HAIR DEFECTIVE3 is involved in nitrogen starvation-induced anthocyanin accumulation

Anthocyanin accumulation is a common phenom-enon seen in plants under environmental stress. In this study, we identified a new allele of ROOT HAIR DEFECTIVE3 (RHD3) showing an anthocyanin overaccumulat...     

The FUSCA genes of Arabidopsis: negative regulators of light responses

More than 200 fusca mutants of Arabidopsis have been isolated and characterised, defining 14 complementation groups. Mutations in at least nine FUSCA genes cause light-dependent phenotypic changes in the absence of light: high levels of anthocyanin accumulation in both the embryo and the seedling, inhibition of hypocotyl elongation, apical hook opening, and unfolding of cotyledons. In double mutants, the fusca phenotype is epistatic to the hy phytochromedeficiency phenotype, indicating that the FUSCA genes act downstream of phytochrome. By contrast, the accumulation of anthocyanin is suppressed by mutations in TT and TTG genes, which affect the biosynthesis of anthocyanin, placing the FUSCA genes upstream of those genes. Regardless of the presence or absence of anthocyanin, fusca mutations limit cell expansion and cause seedling lethality. In somatic sectors, mutant fus1 cells are viable; expressing tissue-specific phenotypes: reduced cell expansion and accumulation of anthocyanin in subepidermal tissue, formation of ectopic trichomes but no reduced cell expansion in epidermal tissue. Our results suggest a model of FUSCA gene action in light-induced signal transduction.     

Roles of pollination and short-chain saturated fatty acids in flower senescence

Pollination induced an immediate increase in ethylene production in Dianthus caryophyllus and Petunia hybrida. In Cymbidium, a lag of several hours was observed. In all three species, pollination induced premature flower senescence. Treatment of the stigmatic surface with aminoethoxyvinylglycine prior to pollination effectively blocked the increase in ethylene production and alleviated the detrimental effect of pollination on flower life.In all three tested species, octanoic and decanoic acids, when applied to the stigmatic surface, had no effect on ethylene production and flower life. In isolated Cymbidium lips placed with their cut base in solutions containing these fatty acids, no effects on red colouration, ethylene production, and ethylene forming enzyme activity were observed. In addition, ethylene sensitivity of isolated lips was not affected. The putative regulatory role of short-chain saturated fatty acids in (pollination-induced) flower senescence is discussed.     

Ethylene, light, and anthocyanin synthesis

Ethylene control of anthocyanin formation functions only through light-initiated synthesis pathways of the rapid synthesis phase. Treatment with ethylene in the dark had no effect on dark anthocyanin synthesis in red cabbage (Brassica oleracea L.). Pretreatment of both red cabbage and sorghum (Sorghum vulgare L.) with ethylene for 24 hours in the dark did increase the rate of synthesis when the tissue was placed in the light. Light-initiated anthocyanin synthesis is inhibited by ethylene when the tissue is returned to the dark.     

Ethylene control of anthocyanin synthesis in sorghum

Light-induced anthocyanin synthesis in Sorghum vulgare L. seedlings was both promoted and inhibited by ethylene treatment. The rate of anthocyanin formation in sorghum tissue was dependent upon the time of ethylene treatment in relation to light exposure and the stage of the anthocyanin synthesis process. Those plants receiving ethylene treatment during the early lag phase of anthocyanin synthesis had higher anthocyanin content at 24 hours than control plants receiving no ethylene treatment. Plants receiving ethylene treatment after the lag phase had lower anthocyanin content at 24 hours than control plants receiving no ethylene treatment.     

The Role of Ethylene in Growth and Endopolygalacturonase Production by Sclerotium rolfsii

Growth of and endopolygalacturonase production by Sclerotium rolfsii was better on a defined mineral medium than on a medium containing segments of tomato leaf petioles. The effect of treatment with ethylene (10μl/l) upon endopolygalacturonase activity with investigated at various stages of growth, in a mineral defined medium. Addition of ethylene to a 10 days-old culture of S. rolfsii resulted in a decrease in activity by day 14, whereas the addition of ethylene to a 4, 6 and 8 days old cultures resulted in an increase in endopolygalacturonase activity. Ethylene seems to have little or no stimulating effect upon growth of S. rolfsii when applied after 8 days. However, inhibited fungal growth, after the addition of ethylene at earlier stages of growth, was obtained due to the depletion of oxygen from sealed culture flasks. Endopolygalacturonase was extracted and purified from control cultures after 14 days of growth. Fractionation of this enzyme protein on Sephadex G-100 gel filtration columns resulted in two peaks of activity measured by the release of reducing sugars from polygalacturonic acid (PGA).     

Formation of higher alcohols and phenol by strains of zymomonas sp.

Strains of the bacteria Zymomonas sp. were studied for their ability to form higher alcohols. In a complex growth medium, six strains were shown to produce significant amounts of 1-propanol, 1-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, pentanols, secondary hexyl-alcohols, and trace amounts of n-hexanol. When resting cells of these organisms were placed into a fermentation medium containing glucose and Tris-buffer, Z. mobilis 8938 produced increased levels of 1-butanol, and secondary hexyl-alcohols at concentrations of 13.5 mg/liter and 5.8 mg/liter, respectively. Another strain, Z. mobilis subsp. mobilis B 806, stimulated the formation of 1-propanol and 1-butanol at concentrations of 14.9 mg/liter and 23.52 mg/liter, respectively. Amino acids or amino acid precursors were then added to the fermentation medium. The presence of threonine and α-ketobutyric acid stimulated Z. mobilis 8938 to produce 82.6 mg/liter secondary hexyl-alcohols and 8.0 mg/liter n-hexanol, respectively. Isoleucine and valine increased the production of 2-methyl-1-butanol (394.0 mg/liter) and 3-methyl-1-butanol (113.4 mg/liter), respectively, by Z. mobilis subsp. mobilis B 806. Glutamine enhanced the formation of 2-methyl-2-butanol production to concentrations 38.8 mg/liter in Zymomonas strain B 806. Additional experiments suggested that higher alcohol production could also be accomplished in the absence of glucose when cells were allowed to metabolize the precursors only. The effect of aromatic amino acids on phenol production was determined using resting cells of Zymomonas sp. The maximum yield of phenol (111.6 mg/liter) was found by Zymomonas strain 8938 in the presence of tyrosine. The addition of phenylalanine also stimulated this strain to form 71.4 mg/liter of phenol.     

Production of aflatoxin in corn by a large-scale solid-substrate fermentation process

Culturing of Aspergillus flavus was conducted in static flask cultures and 4 in. × 5 ft columns (containing 7–8 kg corn) to measure the effects of moisture, temperature, and air flow upon growth and the production of aflatoxin. Aflatoxin levels as high as 6200 ppb (dry basis) in 10 days were observed. Conditions were selected (ca. 20% moisture, 0.008 liter air/kg corn/min air flow with 1.5 liter/kg/min recirculated) for production of aflatoxin in 1200 bushels of corn in a 18-ft diam corrugated steel Butler storage bin for preparation of contaminated corn for animal feeding trials and for testing of an ammoniation process for decontamination of aflatoxin in corn. A target level of 1000 ppb aflatoxin was attained.