Specific Rna From Photoperiodically Induced Cotyledons of Pharbitis Nil

Yoshida, Kazuo; Umemura, Keiko; Yoshinaga, Kohei; Oota, Yukito

doi:10.1093/oxfordjournals.pcp.a079255

Cited by 25 publications

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“…Nitrogenous metabolites such as free amino acids, soluble nitrogen and protein nitrogen were studied by Madan (1956), Eowden and Steward (1957), and Crane and Steward (1962). DNA (Bernier et al 1970), RNA (Yoshida et al 1967), organic acids (Becker 1953, Neyland andThimann 1956), and keto acids (Rabson and Steward 1962) were studied under various photoperiods. The use of nucleic acids and protein antimetabolites reduced flowering rates (Salisbury andBonner 1960, Umemura aod Oota 1965).…”

Section: Introductionmentioning

confidence: 99%

Studies on the Flowering Mechanism in Lemna

Maeng

Khudairi

1973

Physiologia Plantarum

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A nitrogen source was needed for the flowering of Lemna gibba L., a long‐day plant, and L. perpusilla Torr., a shortday plant. The level of endogenous amino acids analyzed by an Amino Acid Analyzer, rose during the first few inductive cycles, but was reduced during later stages of the flowering process. Serine and threonine levels increased during the light period and decreased during the dark period in L. perpusilla. Exogenous serine and threonine added to the culture medium at 10−6M increased the rate of flowering by more than 35% over the controls. Cysteine inhibited flowering, while other amino acids had little or no promotive effect on flowering. Serine and threonine increased flowering rate in L. perpusilla only when added during a dark period of the inductive cycle. The addition of amino acids during a light period not followed by a dark period had no effect on flowering.

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Section: Introductionmentioning

confidence: 99%

Studies on the Flowering Mechanism in Lemna

Maeng

Khudairi

1973

Physiologia Plantarum

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“…RNA synthesis in cotyledons, in response to the inductive photoperiod, has been suggested as a necessary part of floral induction in P. nil (1,31). Recently, more direct molecular approaches have been applied to the study of changes in gene expression associated with the photoperiodic induction of flowering.…”

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Structure and Light-Induced Expression of a Small Heat-Shock Protein Gene of Pharbitis nil

et al. 1992

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To isolate genes that are regulated by a photoperiod that promotes flowering in Pharbitis nil, a cDNA library representing mRNA of induced cotyledons was screened by differential hybridization. The DNA sequence of one cDNA clone isolated by this approach, clone 12L, showed homology to plant small heat-shock protein (hsp) genes. P. nil genomic clones hybridizing to clone 12L were isolated, and the DNA sequences of two P. nil small hsp (shsp) genes, shsp-1 and shsp-2, were determined. The derived amino acid sequences of shsp-1 and shsp-2 showed maximum homology to the 17.9-kD soybean hsp, a member of the class 11 cytoplasmic hsps found in plants. A The physiological processes in floral initiation can be divided into three steps: photoperiodic perception by cotyledons, translocation of induced floral stimulus to the shoot tip where floral initiation takes place, and evocation that results in the commitment of the meristem to form flowers. RNA synthesis in cotyledons, in response to the inductive photoperiod, has been suggested as a necessary part of floral induction in P. nil (1, 31). Recently, more direct molecular approaches have been applied to the study of changes in gene expression associated with the photoperiodic induction of flowering. Both qualitative and quantitative differences were found between translatable mRNAs isolated from cotyledons of plants kept in continuous light and from cotyledons of plants that received an inductive dark period (16).To isolate genes whose expression in P. nil cotyledons is regulated by a photoperiod that leads to flowering, we used a differential screening procedure. We report the isolation, sequence, and expression of one of the genes isolated by this approach. We demonstrate that this gene is a member of a multigene family and can potentially encode a low molecular mass hsp4. Expression of one member of this family is regulated by heat shock and by light, and expression of a related member is regulated only by heat shock. MATERIALS AND METHODS PlantsPharbitis nil plants were grown at 230C for 5 d in coolwhite fluorescent light (145 gE m-2 s-1). At this time, they were subjected to an inductive dark period of 12 or 14 h and were subsequently kept in light for 2 h. The cotyledons were excised, and RNA was extracted as described below. Plants that received a red light night break were exposed to 20 min of red light at the 7th hour of the dark treatment.

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“…Studies oPR-uridine incorporation have also confirmed the observations that increased RNA and protein syntheses occur in the shoot apex and in the plumular leaves of Pharbitis (Arzee, Zilberstein, and Gressel, 1975). Yoshida et al (1967) reported the presence of a specific mRNA ("floral stimulus" mRNA) from photoperiodically induced cotyledons ofPharbitis. Arzee, Gressel, and Galun (1970) demonstrated that Actinomycin-D applied to the cotyledons suppresses flowering in Ph arbitis.…”

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Differential Rna Synthesis in the Shoot Apex of Pharbitis Nil During Floral Evocation

Bonner¹,

Gifford²,

Reed³

1991

American J of Botany

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Early events in the evocation of the flower in Pharbitis nil Chois seedlings were investigated by following the incorporation of tritiated uridine into the shoot apex. The uridine was applied to the expanded cotyledons of seedlings at 8 hr into the inductive dark period. The shoot tips were fixed at 20 hr (a 12-hr labeling period). After the 12-hr labeling period there was considerable label throughout the shoot tips of both control plants (dark period interrupted with 5 min of red light at 8 hr) and plants induced to flower. Both RNase and acid hydrolysis removed the nonexchangeable label and the Azure B staining, thus leading to the conclusion that the uridine was incorporated into RNA. Induction in the cotyledons was followed quickly by an increased synthesis of RNA in the rib meristem region of the receptor bud at the time when the floral stimulus is assumed to be arriving. The increase in RNA synthesis is revealed by an increase in the rib meristem/central zone ratio of counts due to the incorporation of tritiated uridine. A comparison of counts in each of the two regions revealed that the change in ratio was due to an increase in the rib meristem and not due to a decrease in the central zone in induced shoot apices. The initial activation of the rib meristem probably occurred by 16 hr from the beginning ofthe dark period. Tendencies in the literature to disregard the role ofthe rib meristem in giving rise to part of the flower are discussed.

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Specific Rna From Photoperiodically Induced Cotyledons of Pharbitis Nil

Cited by 25 publications

References 0 publications

Studies on the Flowering Mechanism in Lemna

Studies on the Flowering Mechanism in Lemna

Structure and Light-Induced Expression of a Small Heat-Shock Protein Gene of Pharbitis nil

Differential Rna Synthesis in the Shoot Apex of Pharbitis Nil During Floral Evocation

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