The opaque-2 Mutation of Maize Differentially Reduces Zein Gene Transcription

Kodrzycki, Robert; Boston, Rebecca S.

doi:10.2307/3869066

Cited by 49 publications

(76 citation statements)

References 14 publications

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“…We do not exclude, however, the possibility that the genes may also be regulated at other levels-e.g., nuclear RNA processing or export from the nucleus, mRNA stability. Similar conclusions about the regulation of storage protein genes have been reported by others (27)(28)(29)(30)(31)(32)(33). Transcriptional Competence of Genes in Dry Seed Nuclei Provides Insight into a Transition in Plant Development.…”

Section: Resultssupporting

confidence: 84%

Transcriptional activities in dry seed nuclei indicate the timing of the transition from embryogeny to germination.

Comai

Harada

1990

Proc. Natl. Acad. Sci. U.S.A.

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To investigate processes regulating the reinitiation of growth and differentiation during seed germination, we have studied the transcriptional activities of sets of genes that are expressed at specific stages of embryogeny and postgermination in the higher plantBrassica napus L. We show that transcripts from a subset of the genes are elongated in nuclei isolated from dry seeds, indicating that these genes are competent to be transcribed in desiccated and quiescent mature embryos. Analysis of the specific transcripts produced in dry seed nuclei indicates that the changes in gene expression patterns associated with germination are not initiated during late embryogeny. The results suggest that the transition from an embryonic to a postgerminative program of development occurs after seeds are rehydrated.In higher plants, embryonic and postgerminative development are separated generally by a period of developmental arrest in which mature embryos are desiccated and metabolically quiescent. There are significant differences in the morphological and physiological processes that occur in embryos and seedlings (see below), and many of these differences result from changes in gene activities (reviewed in refs. 1-5). While a vast majority of the genes expressed during embryogeny are active also during postgermination (6), sets of genes have been identified that are expressed differentially (e.g., see refs. 7-10). For example, there are mRNAs and proteins that accumulate exclusively during embryogeny while others are prevalent in seedlings and are not detected in embryos. The differential expression of these genes supports the concept that variable gene activities underlie physiological differences between embryos and seedlings (2-5, 9, 10).In this study, we have exploited these differences in gene expression patterns to ask when the transition from an embryonic to a postgerminative program of development occurs in Brassica napus L. Using transcription assays in isolated nuclei to study the regulation of genes expressed at specific stages of embryogeny and postgermination, we have shown that nuclei from dry seeds are transcriptionally active in organello. Comparison of the transcripts produced in embryos, dry seeds, and seedlings suggests that the timing of the shift from an embryonic to a postgerminative pattern of gene expression occurs after seeds are rehydrated. MATERIALS AND METHODSPlant Material and Characterization. Plants were grown and embryos were staged as described (9). For wet and dry weight measurements, embryos and seedlings without seed coats were weighed before and after lyophilization. (13). Replicate blots were hybridized individually with 4.3 x 107 cpm of nuclear RNA that was labeled with 32p to equivalent specific activities in nuclei from embryos, seedlings, or leaves. Filters were processed as described (11).RNA Dot Blots. mRNA dot blots were prepared and hybridized as described (9). Briefly, 0.2 Ag of total, polyadenylylated RNA was applied to filters and hybridized with a sequence excess of...

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Section: Resultssupporting

confidence: 84%

Transcriptional activities in dry seed nuclei indicate the timing of the transition from embryogeny to germination.

Comai

Harada

1990

Proc. Natl. Acad. Sci. U.S.A.

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“…Synthesis of zeins occurs in the endosperm of the seed between 10 and 55 days after pollination (DAP) and is preceded by accumulation of zein mRNA [24,39]. Recently it was shown that regulation of zein synthesis occurs transcriptionally as well as post-transcriptionally [15].…”

Section: Introductionmentioning

confidence: 99%

“…The opaque-2 mutation specifically reduces the accumulation of 22 kDa zeins at the level of transcription [13,15]. The opaque-2 locus has been recently cloned by gene tagging [30] and the derived amino acid sequence of the encoded protein contains domains characteristic of some transacting factors.…”

Section: Introductionmentioning

confidence: 99%

The maize zein gene zE19 contains two distinct promoters which are independently activated in endosperm and anthers of transgenic Petunia plants

et al. 1990

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The activity, tissue specificity and temporal expression of the tandem promoter region preceding a maize zein gene (zE19, encoding a 19 kDa zein protein) were tested in transgenic Petunia plants. To simplify the analysis, the tandem promoter as well as each of the two separate promoter regions were fused to the beta-glucuronidase (GUS) reporter gene. All of the three constructs directed the synthesis of GUS in the endosperm of transformed seeds indicating that both separate promoters are independently activated and show the same tissue and cell type specificity observed for zein genes in maize. The kinetics of accumulation and the localization of GUS activity are not coordinated with those of Petunia endogenous seed storage proteins during the development of transformed seeds. Unexpectedly, we detected high levels of GUS activity in anthers of transformed Petunia plants for all three constructs. This appears to reflect the expression pattern of zein genes in maize, since we detect zein transcripts in anthers. Finally, we discuss the possible origin and function of the tandem promoter arrangement on the basis of these data.

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“…The primary effect of the opaque2 mutation is a reduction in the transcription of a specific subset of zein genes (7). This leads to a corresponding decrease in 22-kDa, and to a lesser extent, 15-kDa zein protein compared with wild type.…”

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confidence: 99%

A maize zinc-finger protein binds the prolamin box in zein gene promoters and interacts with the basic leucine zipper transcriptional activator Opaque2

Vicente‐Carbajosa

Moose

Parsons

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

389

354

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The prolamin box (P-box) is a highly conserved 7-bp sequence element (5-TGTAAAG-3) found in the promoters of many cereal seed storage protein genes. Nuclear factors from maize endosperm specifically interact with the P-box present in maize prolamin genes (zeins). The presence of the P-box in all zein gene promoters suggests that interactions between endosperm DNA binding proteins and the P-box may play an important role in the coordinate activation of zein gene expression during endosperm development. We have cloned an endosperm-specific maize cDNA, named prolaminbox binding factor (PBF), that encodes a member of the recently described Dof class of plant Cys 2 -Cys 2 zinc-finger DNA binding proteins. When tested in gel shift assays, PBF exhibits the same sequence-specific binding to the P-box as factors present in maize endosperm nuclei. Additionally, PBF interacts in vitro with the basic leucine zipper protein Opaque2, a known transcriptional activator of zein gene expression whose target site lies 20 bp downstream of the P-box in the 22-kDa zein gene promoter. The isolation of the PBF gene provides an essential tool to further investigate the functional role of the highly conserved P-box in regulating cereal storage protein gene expression.

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The opaque-2 Mutation of Maize Differentially Reduces Zein Gene Transcription

Cited by 49 publications

References 14 publications

Transcriptional activities in dry seed nuclei indicate the timing of the transition from embryogeny to germination.

Transcriptional activities in dry seed nuclei indicate the timing of the transition from embryogeny to germination.

The maize zein gene zE19 contains two distinct promoters which are independently activated in endosperm and anthers of transgenic Petunia plants

A maize zinc-finger protein binds the prolamin box in zein gene promoters and interacts with the basic leucine zipper transcriptional activator Opaque2

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