Ethylene and the Responses to Light of Rice Seedlings

Miller, John H.; Miller, Pauline Monz

doi:10.1111/j.1399-3054.1974.tb03645.x

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…Some investigators (Sweet andHillman 1969, Fox andHillman 1968a) have proposed that the ratio of Pfr to Pris an important controlling factor and that Pr levels have a direct role in photomorphogenesis (Hopkins 1971). Others have found no correlations between in vivo phytochrome spectroscopy and physiological responses to light (Briggs and Chon 1966, Dooskin and Mancinelli 1968, Hillman 1972, Miller and Miller 1974. The lack of correlation is particularly apparent in Briggs' and Chon's (1966) work with maize coleoptiles.…”

Section: Discussionmentioning

confidence: 99%

Phytochrome Control of Longitudinal Growth and Phytochrome Synthesis in Maize Seedlings

Duke

Naylor

Wickliff

1977

Physiologia Plantarum

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The active, far‐red light absorbing, form of phytochrome was found to inhibit growth and phytochrome levels in the mesocotyl and coleoptile of 4‐ to 5.5‐day‐old seedlings of Zea mays L. Short, low‐irradiance red or far‐red light treatments were used to produce different proportions of active phytochrome at the end of highdirradiance white‐light periods, which left different levels of total phytochrome in the plants. After light treatments which left relatively high levels of spectrophotometrically assayable phytochrome in the seedlings, apparent phytochrome synthesis in the subsequent dark period was low regardless of the proportions of each form of the pigment present at the beginning of the dark period. In light treatments producing relatively low levels of assayable phytochrome, levels of apparent phytochrome synthesis in both red and far‐red treatments and differences between apparent synthesis in red and far‐red treatments were maximal. No simple correlation was found between growth and apparent phytochrome synthesis. However, growth and total phytochrome levels were positively correlated in both organs. Using a subtractive method of correlation, in which only phytochrome effects were plotted, strong linear relationships between phytochrome levels or longitudinal growth and Pfr levels were found in those light treatments leaving greater than 8% of dark control levels of phytochrome in the tissues. Using this technique non‐linear, inverse relationships between Pfr and apparent phytochrome synthesis was found, indicating that modes of phytochrome control over phytochrome synthesis and growth differ. Our results are consistent with the view that in vivo assays of “bulk’ phytochrome reflect levels and states of the physiologically active phytochrome fraction under our experimental conditions in maize.

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Section: Discussionmentioning

confidence: 99%

Phytochrome Control of Longitudinal Growth and Phytochrome Synthesis in Maize Seedlings

Duke

Naylor

Wickliff

1977

Physiologia Plantarum

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“…For ACC determinations, the plant material was homogenized and extracted with 60 mM Tris-HCI buffer (pH 7.9). After centrifugation at 13,000g (Micro-Centrifuge, Fisher) for 15 (Fig. 1).…”

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confidence: 99%

Ethylene and the Growth of Rice Seedlings

Satler¹,

Kende²

1985

Plant Physiol.

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ABSTRACT?Etiolated whole rice seedlings enclosed in sealed vials produced ethylene at a rate of 0.9 picomole per hour per seedling. When 2-centimeterlong shoots were subdivided into 5-millimeter-long sections, the sections containing the tip of the shoot evolved 37% of the total ethylene with the remaining 63% being produced along a gradient decreasing to the base of the shoot. The tip of the coleoptile also had the highest level of the ethylene precursor 1-aminocyclopropane-l-carboxylic acid and of the ethylene-forming enzyme activity. Ethylene is one of the factors controlling coleoptile elongation. Decapitation of the seedling reduced ethylene evolution to one-third its original level and inhibited coleoptile growth. In short-term experiments, the growth rate of decapitated seedlings was restored to almost that of intact seedlings by application of ethylene at a concentration of 10 microliters per liter. Apart from ethylene, 02 also participates in the control of coleoptile growth. When rice seedlings were grown in a gas mixture of N2 and 02, the length of the coleoptiles reached a maximum at a concentration of 2.5% 02. Lower and higher concentrations of 02 reduced coleoptile growth. The effect of exogenous ethylene on coleoptile growth was also 02 dependent.A remarkable characteristic of the rice coleoptile is its ability to grow in an environment containing very low levels of 02 or no detectable amounts of 02 at all ( 13, 25). The capacity of this organ to grow under hypoxic conditions has been interpreted as an adaptation ofthe rice seedling to flooding conditions, allowing it to emerge from the water where the 02 concentration is much lower than in the air. This adaptive behavior seems to be shared by all cultivated species of the genus Oryza (13), including the wild rice, Zizania aquatica (2). Echinochloa crus-gaili ( 11) and Peltandra virginica (3) are also able to germinate and grow under hypoxic conditions. In low 02, the growth of rice seedlings is restricted to the coleoptile and mesocotyl while root and leaf growth is severely inhibited (22 NaOCI) for 10 min, followed by many rinses with tap and distilled H20.Germination. Seeds were germinated in darkness at 30± 0.2°C under two different conditions to vary coleoptile height. In most experiments, 1-cm-long coleoptiles were used which were obtained by germinating seeds in 14-cm Petri dishes containing 30 ml of distilled H20 for 2 to 3 d. In some experiments, longer coleoptiles (about 2 cm) were needed; these were obtained by germinating seeds in plastic boxes (20 x 10 x 8 cm) covered with 905 Reynolds plastic film. Six-hundred seeds and 20 ml of distilled H20 were placed in each plastic box, and the seedlings were grown for 6 d. Under these conditions, the coleoptiles grow taller because the duration of coleoptile growth is extended in sealed containers (see e.g. Raskin and Kende [ 18] Fig. 4). The whole seedling was placed in a glass chamber containing 1.5 ml of water, which was enough to cover half of the seed.Growth of Seedligs in Sealed and Flow-...

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“…Examples of the latter phenomenon include fern protonema (14), aquatic species of angiosperms (10,17), and mesocotyl tissues of oats and rice (16). When applied to rice seedlings (13) or to Onoclea protonema (14), ethylene promotes cellular elongation, although in the later prothallial stage of Onoclea, the ethylene promotion is absent (6). In some aquatic plant systems, combined ethylene-CO2 treatment not only stimulates tissue elongation, but ethylene and CO2 are synergistic (17).…”

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Carbon Dioxide and Ethylene Control of Spore Germination in Onoclea sensibilis L

Edwards¹

1977

Plant Physiol.

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In gametophytes of the sensitive fern, Onoclea sensibilis L., ethylene is a natural product of metabolism. One of the first determinations of the effect of ethylene specifically at the cellular level was with Onoclea gametophytes: cell division in different stages of gametophytic development, both protonemal and prothallial, is reduced by ethylene (6,14). Germination of unicellular Onoclea spores also is inhibited by ethylene (7). Likewise, in many multicellular systems, ethylene is inhibitory to growth (1). In most higher plant systems, ethylene inhibition is reversed by C02, which acts competitively with ethylene (3, 4).Not all studies find inhibition when plants are treated with ethylene. Instead, some tissues and cells respond to ethylene by elongating. Examples of the latter phenomenon include fern protonema (14), aquatic species of angiosperms (10, 17), and mesocotyl tissues of oats and rice (16). When applied to rice seedlings (13) or to Onoclea protonema (14), ethylene promotes cellular elongation, although in the later prothallial stage of Onoclea, the ethylene promotion is absent (6). In some aquatic plant systems, combined ethylene-CO2 treatment not only stimulates tissue elongation, but ethylene and CO2 are synergistic (17). Thus, depending upon species and/or developmental stage, the effects of ethylene and CO2 may differ.Although ethylene was demonstrated to be inhibitory to cell division and spore germination in ferns (6, 7), the particular effect of CO2 on spore germination was not investigated previously. The present study was undertaken to determine the influence of CO2 and ethylene on the light-dependent germination of Onoclea spores.MATERIALS AND METHODS Spore Sterilization and Storage. Procedures similar to those described previously (7) were followed with some modifications. Fertile fronds of 0. sensibilis L. were collected in December, 1972, near Tully, N. Y., and stored initially at 4 C. Portions of a single frond were sterilized, dried overnight in a vacuum desiccator, and filtered through 100 ,um nylon mesh. The resultant spore fraction was collected aseptically in a Petri dish, wrapped with Parafilm around the edges, placed in a plastic bag, and stored at -20 C. When spores were needed, they were removed from the freezer and sown. Unused portions were returned to storage. Over a period of 20 months, spores were treated to several dozen cycles of warming and storing without any loss of viability. Germination by controls was about 95%.Culturing. Spores were cultured in glass tubes (25 x 100 mm) containing 10 ml of Knops solution (pH 5), and covered with stainless steel caps (28 x 38 mm) (7). Carbon dioxide uptake and alteration of pH of the buffered Knops solution were negligible for applied CO2 of 5% (v/v) or less. When checked with a pH meter, culture media exhibited no pH change after 48 hr incubation with 5% CO2. Culture media and materials were sterilized by autoclaving 10 min at 121 C and 1.05 kg cm-2. Approximately equal numbers of spores were inoculated aseptically. Following ino...

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Ethylene and the Responses to Light of Rice Seedlings

Cited by 6 publications

References 17 publications

Phytochrome Control of Longitudinal Growth and Phytochrome Synthesis in Maize Seedlings

Phytochrome Control of Longitudinal Growth and Phytochrome Synthesis in Maize Seedlings

Ethylene and the Growth of Rice Seedlings

Carbon Dioxide and Ethylene Control of Spore Germination in Onoclea sensibilis L

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