Altered tissue specificity of the revertant shrunken allele upon Dissociation (Ds) excision is associated with loss of expression and molecular rearrangement at the corresponding non-allelic isozyme locus in maize

Chourey, Prem S.; DeRobertis, G. A.; Still, P. E.

doi:10.1007/bf00337725

Cited by 12 publications

(16 citation statements)

References 32 publications

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“…The isolation of Sh'-5 sus and sh sus genotypes has been described previously (ref. 21; unpublished data). The new genetic stocks, Sh sus and Sh'-5 Sus, were obtained by crossing the standard W22 inbred strain, Sh Sus, with sh sus and the Sh'-5 sus with sh Sus (the sh bz-m4 stock) stocks, respectively.…”

Section: Methodsmentioning

confidence: 90%

“…Despite such dichotomy in tissue and cell specificities as well as in the inductional properties of Sh and Sus loci, it was intriguing that a mutant sus genotype lacking the SS2 protein showed no detectable phenotypic change in the plant (21). We demonstrate here, based on the combined use of appropriate genetic strains, gene-specific cDNA probes, and isozyme-specific monoclonal antibodies, that genetically redundant Sh and Sus loci are cross-regulated and are also functionally redundant.…”

mentioning

confidence: 88%

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Epistatic interaction and functional compensation between the two tissue- and cell-specific sucrose synthase genes in maize.

Chourey¹,

Taliercio²

1994

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

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A tissue-specific epistatic mode of gene interaction was observed between molecularly homologous genes Sh1 and Sus1 (hereafter, Sh and Sus), encoding the sucrose synthase (SS) isozymes, SS1 and SS2, respectively. In Sh Sus genotype, both SS genes were expressed simultaneously and approximately equally in young seedlings; however, only the Sus-encoded SS2 protein was seen in the developing embryos. By contrast, the mutant sus genotype, lacking detectable levels of the SS2 protein in various tissues tested, showed expression of the Sh locus as judged by the detection of the SS1 protein in such embryos. Ectopic expression in embryos was seen from two separate Sh alleles, Sh-W22 and Sh'-5 (a revertant allele derived upon Ds excision from sh-m5933). In each case, the Sh expression at the protein level in embryos was unique to genotypes with the mutant sus gene. Based on the observed lack of phenotypic change in the sus mutant, we suggest that the ectopic expression of the Sh in otherwise Sus-specific tissues leads to functional compensation. There was no epistatic interaction of Sh and Sus at the RNA level as SS1 transcripts were detectable in both Sus and sus embryos. Thus, embryo specificity between the two SS genes was determined at posttranscriptional or at translational level of control. We surmise on the basis of these data that metabolic regulatory controls seem to override the normal constraints of tissue and cell specificity of the nonallelic isozyme genes to maintain efficient use of the pathways.

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Section: Methodsmentioning

confidence: 90%

mentioning

confidence: 88%

Epistatic interaction and functional compensation between the two tissue- and cell-specific sucrose synthase genes in maize.

Chourey¹,

Taliercio²

1994

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

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“…The maize SS2 MCA used here is highly specific as it does not show any cross-reactivity with the maize SS1 isozyme (our unpublished data). We have previously characterized the maize immature embryo isozyme to be SS2-specific (3,7,12). Conservations of epitope as well as embryo specificities of the SS2 protein in maize and sorghum are of significant interest.…”

Section: Rna Blots and Anaerobic Expressionmentioning

confidence: 99%

Tissue-Specific Expression and Anaerobically Induced Posttranscriptional Modulation of Sucrose Synthase Genes in Sorghum bicolor M.

Chourey¹,

Taliercio²,

Kane³

1991

Plant Physiol.

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We have used antibodies directed against the two sucrose synthase (SS) isozymes, and the cDNA clones corresponding to the two nonallelic genes in maize to describe sorghum (Sorghum bicolor) SS genes and their expressions at protein and RNA levels. Westem blot analyses have shown evidence of two SS isozymes, SS1 and SS2, in sorghum; these were similar, but not identical, to maize isozymes in size, charge, subunit composition, and epitope specificities against both monoclonal and polyclonal antibodies. Tissue-specific distributions of isozymes and genomic Southern hybridization data are consistent with a hypothesis that the SS1 and SS2 isozymes are encoded by two nonallelic genes, designated here as Susl and Sus2, respectively. Northem blot hybridizations on root RNAs showed gene-specific transcript patterns and, as in maize, the SS2-specific transcripts were slightly larger than the SS1-specific transcripts. Interestingly, no difference in the size of the SS1 and SS2 polypeptides was detected. Anaerobic induction led to significant elevations in steady-state levels of both SS1 and SS2 transcripts, but there was no detectable increase in the levels of the SS proteins. Thus, both the SS genes in sorghum were significantly regulated at the posttranscriptional level; whereas in maize, only one of the two SS genes was affected in this fashion. Another difference between maize and sorghum SS isozymes was in endospermspecific polymerization among the SS subunits. Unlike maize endosperm where only the two SS homotetramers are seen, sorghum endosperm showed five SS isozymes attributable to a random copolymerization of SS1 and SS2 subunits, presumably due to a simultaneous expression of both genes in the endosperm cells. Physiological and molecular bases of these differences between these two crop plant species remains to be elucidated.The enzyme SS2 (EC 2.4.1.13) plays an important role in energy metabolism by mobilizing sucrose into diverse pathways relating to metabolic, structural, and storage functions of the plant cell. The enzyme catalyzes reversible conversion of UDP and sucrose to UDP glucose and fructose and has 'Cooperative investigation,

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“…Loss of susl function is reported to have no phenotypic effect on the maize plant (Chourey, 1988;Chourey et al, 1988). This suggests then that, although susl is expressed in all tissues of the maize plant, its function is dispensable.…”

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confidence: 99%

Structural Features of the Maize sus1 Gene and Protein

et al. 1994

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Genomic clones, cDNA clones, and protein of the maize (Zed mays 1.) Suc synthase1 (susl) gene were isolated and sequenced. Termini (5' and 3') of the transcribed unit were identified. The SUSl protein was purified from tissue culture cells as a phosphorylated protein. The overall structure of susl is virtually identical with that of the paralogous gene, shrunken1 (shl); however, the last intron of s h l is missing i n susl. This intron bears much sequence similarity with the adjacent exon, suggesting that the intron arose from an internal duplication. Although the placement of the other 14 introns is identical in both genes, the introns exhibit markedly greater differences in size and sequence relative to that shown by the exons. An explanation for the differential rate of divergence of exons and introns is selection pressure for gene function. Additionally, comparisons of coding regions of plant sucrose synthases show that shl-like and susl-like genes can be found in all monocots so far analyzed. These latter observations point to an important role played by both genes in this group of plants.

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Altered tissue specificity of the revertant shrunken allele upon Dissociation (Ds) excision is associated with loss of expression and molecular rearrangement at the corresponding non-allelic isozyme locus in maize

Cited by 12 publications

References 32 publications

Epistatic interaction and functional compensation between the two tissue- and cell-specific sucrose synthase genes in maize.

Epistatic interaction and functional compensation between the two tissue- and cell-specific sucrose synthase genes in maize.

Tissue-Specific Expression and Anaerobically Induced Posttranscriptional Modulation of Sucrose Synthase Genes in Sorghum bicolor M.

Structural Features of the Maize sus1 Gene and Protein

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