The nucleotide sequence of a cDNA clone encoding the wheat E<sub>m</sub>protein

Litts, James C.; Colwell, Greggory W.; Chakerian, R.; Quatrano, Ralph S.

doi:10.1093/nar/15.8.3607

Cited by 111 publications

(57 citation statements)

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“…pEMB-1 hybridized to a single species of poly(A) RNA of about 560 bases in length. The abundance of this mRNA was at least 40-fold higher in 1 EMB-I met ala ser * * * gln gln g l u l y s l y s g l u leu asp ala arg * * * l Y S E m -1 ala arg g l n gly glu thr val val pro g l y g l y thr gly gly lys (Ulrich et al, 1990) is compared with that of the Em protein of wheat (Litts et al, 1987). Dashes indicate identical amino acids; the asterisks represent an absent amino acid.…”

Section: Embryo-specific Accumulation Of Emb-1 Mrnamentioning

confidence: 99%

“…The cDNA sequence contains a 279-bp translational open reading frame. Figure 3 shows the amino acid sequence of the protein predicted from the pEMB-1 cDNA sequence (Ulrich et al, 1990) and its comparison with a derived wheat Em amino acid sequence (Litts et al, 1987).…”

Section: Emb-1 Proteinmentioning

confidence: 99%

“…Genes homologous to the emb-l gene may be expressed in all monocot and dicot embryos (Cuming, 1984;Litts et al, 1987;Baker et al, 1988;Raynal et al, 1989;Ulrich et al, 1990;Williams and Tsang, 1991;Espelund et al, 1992). Genes from cotton (Leu D19 gene) and from wheat (Em gene) that code for proteins similar to that encoded by EMB-1 are expressed primarily at the time of embryo desiccation or in response to ABA (Dure et al, 1989;Marcotte et al, 1989;Hughs and Galau, 1991).…”

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Characterization of a Gene That Is Expressed Early in Somatic Embryogenesis of Daucus carota

et al. 1993

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Section: Embryo-specific Accumulation Of Emb-1 Mrnamentioning

confidence: 99%

Section: Emb-1 Proteinmentioning

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Characterization of a Gene That Is Expressed Early in Somatic Embryogenesis of Daucus carota

et al. 1993

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“…Southern hybridization analyses of all the clones were conducted with cDNA clones for some known ABA-responsive genes including barley dehydrin (10), Em (22) dormant grain axes. In the nondormant axes, transcript levels declined following imbibition.…”

Section: Isolation and Southern Analyses Of Cdna Clones Prevalent In mentioning

confidence: 99%

Molecular Cloning and Expression of Abscisic Acid-Responsive Genes in Embryos of Dormant Wheat Seeds

Morris¹,

Anderberg²,

Goldmark³

et al. 1991

Plant Physiol.

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Hydrated dormant cereal seeds do not germinate even when environmental conditions are favorable for germination. By using cDNA cloning and differential screening, we have identified mRNAs from five gene families that are abundant in the embryos of imbibed, but developmentally arrested wheat (Triticum aestivum L.) seeds. Gene transcript levels of these mRNAs are maintained and even increase in embryos of imbibed dormant seeds for as long as the seeds remain dormant. In contrast, transcript levels decline in nondormant seeds after imbibition and disappear as germination occurs. All the identified genes are ABA responsive. Based on these data we conclude that wheat seeds in the hydrated dormant state exhibit prolonged expression of ABAresponsive genes.Upon hydration, most mature seeds germinate readily over a range of environmental conditions. By contrast, dormant seeds do not germinate under conditions favorable for germination and can remain viable in a hydrated state for prolonged periods without cell elongation until a signal is recognized by the seed embryo which initiates germination. The mechanism of seed dormancy poses an intriguing problem in plant molecular biology and has major agricultural importance. For the first few hours after imbibition dormant and nondormant seeds exhibit similar physiological responses, including the same rates of water uptake and new protein synthesis (6). In dormant seeds, however, there appear to be molecular and biochemical restrictions which prevent cell expansion and germination. The intent of this research is to contribute toward the identification of the restrictions which regulate seed dormancy in mature seeds.In some plant species seed dormancy is released by prolonged storage of dry seeds (afterripening), while other species require hydration at low temperatures (6,20). Proposed dormancy mechanisms in mature seeds have focused on regulation by inhibitors acting alone or in combination. Such mechanisms have included those attributed to the seed coat such 'Contribution from the U.S.

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“…Levels of Em mRNA normally increase dramatically during maturation of wheat (27) and maize embryos (23), but expression of the Em gene is also observed in vegetative tissue exposed to ABA or osmotic stress (16,27). The Em gene is well characterized (7,18), and functional regions within its promoter involved in the ABA response have been identified (15,20,21,27). Regulation of Em expression by ABA has been shown to occur at the transcriptional level as well as at a posttranscriptional step (34).…”

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Regulation of Em Gene Expression in Rice

Bostock¹,

Quatrano²

1992

Plant Physiol.

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Expression of the Em gene was characterized in rice (Oryza sativa L.) suspension cultures following exposure of the cultures to various combinations of abscisic acid (ABA) and salt. Response-saturating concentrations of either ABA (50 micromolar) or NaCI (0.4 molar) rapidly induced (by 60 minutes) the accumulation of Em mRNA, with a maximum accumulation occurring 12 to 24 hours after treatment. NaCI-induced Em expression was accompanied by a doubling of endogenous ABA levels as determined by immunoassay. Inhibition of ABA biosynthesis by fluridone during NaCI treatment reduced the levels of endogenous ABA by fourfold and Em expression by 50%. Desiccation of the cultures to 12 to 15% of their initial fresh weight increased endogenous ABA more than twofold and was accompanied by an increase in Em mRNA levels. Exposure of the cultures to heat shock temperatures, chilling, or ultraviolet light neither increased endogenous ABA levels nor induced Em expression. When a subthreshold or saturating level of NaCI was added in combination with increasing levels of ABA, Em transcripts were detected at ABA concentrations that alone did not induce expression of Em. Treatment with saturating levels of both NaCI and ABA resulted in a doubling of Em transcript levels over the maximum signal for each treatment alone. Hence, our data suggested that salt interacted synergistically with ABA, in part because of the increased sensitivity of rice cells to ABA. The effect of salt stress on Em gene expression in rice suspension cells appeared to operate through two pathways: one is mediated through increases in the level of ABA; the other is via a unique salt response pathway that includes an intermediate that is common to both the salt and ABA response chains.Physiological and molecular responses to ABA are controlled by the levels of ABA as well as by the sensitivity of tissues that are competent to respond (16,17,35). One factor that appears to alter the response of plant cells to ABA is V.The interaction between reduced v and ABA has been experimentally well illustrated in rapeseed germination (29) germination (26). Schopfer and Plachy (29) showed that reduced I imposed by osmotic stress and ABA can quantitatively substitute for each other to inhibit rapeseed germination. For example, 50% inhibition of rapeseed germination is achieved with either 22 lsM ABA, 10 gM ABA + 6 bars osmoticum, or 11 bars osmoticum. This two-factor interaction results in a shift in the concentration-response curve for ABA inhibition of germination toward lower ABA concentrations in the presence of an osmoticum, i.e. an osmotically induced change in the sensitivity of the tissue to ABA.The capacity of exogenous ABA or osmoticum to quantitatively substitute for each other suggests a common intermediate in the osmotic stress and ABA response pathways. It is unclear, however, whether osmotic stress operates solely through changes in ABA levels to effect the response. Evidence for osmoticum operating through ABA has been suggested by studies in which e...

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The nucleotide sequence of a cDNA clone encoding the wheat E_mprotein

Cited by 111 publications

References 29 publications

Characterization of a Gene That Is Expressed Early in Somatic Embryogenesis of Daucus carota

Characterization of a Gene That Is Expressed Early in Somatic Embryogenesis of Daucus carota

Molecular Cloning and Expression of Abscisic Acid-Responsive Genes in Embryos of Dormant Wheat Seeds

Regulation of Em Gene Expression in Rice

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The nucleotide sequence of a cDNA clone encoding the wheat Emprotein

Cited by 111 publications

References 29 publications

Characterization of a Gene That Is Expressed Early in Somatic Embryogenesis of Daucus carota

Characterization of a Gene That Is Expressed Early in Somatic Embryogenesis of Daucus carota

Molecular Cloning and Expression of Abscisic Acid-Responsive Genes in Embryos of Dormant Wheat Seeds

Regulation of Em Gene Expression in Rice

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The nucleotide sequence of a cDNA clone encoding the wheat E_mprotein