Disappearance of stored polyadenylic acid and mRNA during early germination of radish (Raphanus sativus L.) embryo axes

Delseny, Michel; Aspart, Lorette; Guitton, Yves

doi:10.1007/bf00387160

Cited by 51 publications

(20 citation statements)

References 12 publications

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“…Conserved mRNA has been shown to be present in a variety of dry plant embryos and seeds [3,8,21 -231 but little is yet known about its role during early germination. There have been suggestions that, in different plant systems, some of this mRNA may not be translated [24], some may be degraded [21], Fig.…”

Section: Discussionmentioning

confidence: 99%

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Protein Synthesis in Imbibing Wheat Embryos

Cuming

Lane

1979

European Journal of Biochemistry

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Polypeptides synthesized by imbibing wheat embryos have been compared with those made by cell-free extracts programmed with bulk poly(A)-rich RNA from dry wheat embryos. Newly synthesized polypeptides, labeled with [35S]methionine, were resolved by one-dimensional and two-dimensional electrophoresis and then records of the separations were prepared by fluorography. When programmed by bulk poly(A)-rich RNA from dry wheat embryos, a nuclease-treated rabbit reticulocyte lysate synthesizes an array of polypeptides which is broadly similar to that formed when a wheat germ extract is programmed with the same RNA. Polypeptides made in both homologous and heterologous cell-free systems, under the direction of bulk poly(A)-rich RNA from dry wheat embryos, are broadly similar to those formed during early (0-40 min) imbibition of dry wheat embryos. As imbibition progresses beyond 40 min, there are profound changes in the one-dimensional and twodimensional electrophoretic distributions of newly made polypeptides present in the 23 000 x g supernatant fraction of cell-free homogenates; characteristically, low-molecular-weight and basic polypeptides comprise a diminishing proportion of the total polypeptides as imbibition progresses beyond 40 min. Ribosomal proteins are conspicuous among the proteins formed during early imbibition and especially prominent among the products formed when homologous cell-free polypcptide synthesis is programmed by bulk poly(A)-rich RNA from dry wheat embryos.

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Section: Discussionmentioning

confidence: 99%

“…There have been suggestions that, in different plant systems, some of this mRNA may not be translated [24], some may be degraded [21], Fig. 4.…”

Section: Discussionmentioning

confidence: 99%

Protein Synthesis in Imbibing Wheat Embryos

Cuming

Lane

1979

European Journal of Biochemistry

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“…The results suggest that translation of newly synthesized mRNA occurs after a delay of several hours (4,5,7,11 molecules (27). In this material, the initial water uptake is completed after 30 min (19).…”

Section: Introductionmentioning

confidence: 82%

Newly Synthesized mRNA Is Translated during the Initial Imbibition Phase of Germinating Maize Embryo

Dommès

Walle

1983

Plant Physiol.

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RNA synthesis is activated in the cells of the plant embryo very soon after the start of seed imbibition. We previously reported that mainly heterogeneous nuclear RNA is synthesized in the radicle of Zea mays embryo during the first hours of germination. The present study was undertaken in order to detect the time of appearance of the newly synthesized messenger RNA in the polysomes of germinating maize axes.Free polysomes were prepared from embryonic axes rehydrated for 2 hours in the presence of radioactively labeled uridine. These polysomes were shown to be labeled and to contain labeled particles sedimenting, after dissociation with EDTA, in the 1OS to 40S region of a sucrose gradient. The labeled polysomal RNA migrates heterogeneously in a gel with a mean size corresponding to about 16S, and 60% of these molecules are polyadenylated.The data indicate that the newly synthesized RNA associated with the polysomes after 2 h of germination consists of messenger RNA molecules. Analysis of the polysomes prepared 0.5 and 1 h after the start of imbibition suggests that translation of the newly synthesized messenger RNA probably occurs within the 1st hour of imbibition of the isolated axis, thus well before the completion of the initial water uptake.Rehydration of a quiescent embryo under appropriate conditions induces the rapid reactivation of protein synthesis (20). Several studies showed that this phenomenon is not affected by the presence of transcription inhibitors (4,7,11,26,29). These results suggest that, during early germination, protein synthesis is not dependent on de novo mRNA synthesis, but rather is the consequence of polysome formation from preformed mRNA. This interpretation is supported by the fact that mRNA extracted from quiescent seeds is translatable in vitro (9).The effect oftranscription inhibitors on the synthesis ofprotein was examined at different times after the start of imbibition. The results suggest that translation of newly synthesized mRNA occurs after a delay of several hours (4,5,7,11 molecules (27). In this material, the initial water uptake is completed after 30 min (19). Similar observations were made in cotton embryos and radish axes labeled at a more advanced stage of germination (8, 11). It is surprising that these observations were not extended to the period of initial water uptake because they suggest that, in addition to the translation of preformed mRNA, new transcripts assume a functional role in protein synthesis soon after the start ofimbibition. Recently, the possible significance of the newly synthesized mRNA was pointed out by quantitative determination ofthe mRNA content in germinating tissues. It was shown that the synthesis ofgluconogenic organelles in germinating castor bean endosperm is accompanied by a large increase in translatable mRNA (25). A similar increase was also described in cotyledons ofgerminating cucumber and it was also shown, in the same tissue, that the rise in activity of isocitrate lyase and malate synthase is preceded by an increase in ...

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Section: Introductionmentioning

confidence: 99%

“…An essential step during these earliest stages of seed germination is de novo synthesis of proteins, probably mediated by a preformed mRNA (7,15, 35) as showed by its independence of de novo RNA synthesis (34, 35). While the presence of preformed mRNA in embryos is well documented in the literature (3,4,6,7,16,20,21,28) its presence in cotyledons is not so well established ( 18).As an approach to this problem, we describe in the present paper the isolation from cotyledons of ungerminated dry seeds of Cicer arietinum of a polyadenylic-rich RNA with messenger characteristics, as shown by its ability of translation in two systems of in vitro protein synthesis: wheat germ extracts and rabbit reticulocyte lysates. In addition, the in vitro products were analyzed by polyacrylamide gel electrophoresis and autoradiography.…”

mentioning

confidence: 96%

Preformed mRNA in Cotyledons of Ungerminated Seeds of Cicer arietinum L.

Matilla¹,

Nicolás²,

Vicente³

et al. 1980

Plant Physiol.

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Polyadenylated RNA was isolated from total RNA extracted from cotyledons of ungerminated or 18-hour-germinated chick-pea seeds by affinity chromatography on oligo(dT)-cellulose. Both poly(A)-containing RNA fractions exhibited a template activity when assayed in two cell-free translation systems, wheat germ extracts, and nuclease-treated reticulocyte lysates. Translation of preformed mRNA from cotyledons of dry seeds was completely abolished in the presence of several inhibitors of polypeptide chain initiation and also in the presence of the two "cap" analogues m7GTP and m7GMP. The patterns of polypeptides synthesized by translation of poly(A)-containing RNAs from cotyledons of ungerminated or 18-hourgerminated seeds, in the wheat germ system, analyzed by electrophoresis and autoradiography, were similar but not identical. It is concluded that cotyledons of dry Cicer arietinum L. seeds contain preformed mRNA.The resumption of growth by a seed requires water and a suitable temperature. During imbibition there is a dramatic increase in metabolic activity. An essential step during these earliest stages of seed germination is de novo synthesis of proteins, probably mediated by a preformed mRNA (7,15, 35) as showed by its independence of de novo RNA synthesis (34, 35). While the presence of preformed mRNA in embryos is well documented in the literature (3,4,6,7,16,20,21,28) its presence in cotyledons is not so well established ( 18).As an approach to this problem, we describe in the present paper the isolation from cotyledons of ungerminated dry seeds of Cicer arietinum of a polyadenylic-rich RNA with messenger characteristics, as shown by its ability of translation in two systems of in vitro protein synthesis: wheat germ extracts and rabbit reticulocyte lysates. In addition, the in vitro products were analyzed by polyacrylamide gel electrophoresis and autoradiography. MATERIALS AND METHODSPlant Material. Cotyledons of C. arietinum L. obtained either from ungerminated seeds or from seeds germinated for 18 h were used. Seeds of C. arietinum were soaked for 5 min in 0.1% NaOCl and washed thoroughly with sterile distilled H20. They were germinated in the dark at 25 C on moist filter paper in Petri dishes Supported by grants from Comision Asesora de Investigation Cientifica y Tecnica (Spain). and then separated into cotyledons and embryos after removal of the seed coat.Preparation of Total RNA. Chick-pea cotyledons were suspended in 0.1 M Tris-HCl (pH 9.0) containing 0.1 M NaCl, 10 mm EDTA, 0.5% SDS, and 2 mg/ml bentonite, at the concentration of 0.6 g (wet weight)/ml, and homogenized in Omni-Mixer.Redistilled 80%o aqueous phenol was added to the homogenate and the RNA extracted for I h at room temperature. After separation of phases by centrifugation at 5,000g for 10 min, the phenol phase was reextracted with one volume of the extraction buffer. The combined water phases were extracted twice more with 80%o phenol. The final water phase was made 0.2 M with respect to K-acetate (pH 5.0) and the RNA was precipitate...

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Disappearance of stored polyadenylic acid and mRNA during early germination of radish (Raphanus sativus L.) embryo axes

Cited by 51 publications

References 12 publications

Protein Synthesis in Imbibing Wheat Embryos

Protein Synthesis in Imbibing Wheat Embryos

Newly Synthesized mRNA Is Translated during the Initial Imbibition Phase of Germinating Maize Embryo

Preformed mRNA in Cotyledons of Ungerminated Seeds of Cicer arietinum L.

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