The Maize Glutamine Synthetase GS1- Gene is Preferentially Expressed in Kernel Pedicels and is Developmentally-Regulated

Rastogi, Rajeev; Chourey, Prem S.; Muhitch, Michael J.

doi:10.1093/oxfordjournals.pcp.a029388

Cited by 24 publications

(11 citation statements)

References 21 publications

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“…OsGS1;3 was expressed mainly in spikelets. Similar results were obtained in maize in which one of the five GS1 genes is also preferentially expressed in kernel pedicels (Rastogi et al. , 1998).…”

Section: Discussionsupporting

confidence: 82%

Severe reduction in growth rate and grain filling of rice mutants lacking OsGS1;1, a cytosolic glutamine synthetase1;1

et al. 2005

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SummaryRice (Oryza sativa L.) plants possess three homologous but distinct genes for cytosolic glutamine synthetase (GS1): these are OsGS1;1, OsGS1;2, and OsGS1;3. OsGS1;1 was expressed in all organs tested with higher expression in leaf blades, while OsGS1;2, and OsGS1;3 were expressed mainly in roots and spikelets, respectively. We characterized knockout mutants caused by insertion of endogenous retrotransposon Tos17 into the exon-8 (lines ND8037 and ND9801) or the exon-10 (line NC2327) of OsGS1;1. Mendelian segregation occurred in each progeny. Homozygously inserted mutants showed severe retardation in growth rate and grain filling when grown at normal nitrogen concentrations. Abnormal mRNA for GS1;1 was transcribed, and the GS1 protein and its activity in the leaf blades were barely detectable in these mutants. The glutamine pool in the roots and leaf blades of the mutants was lower than that of the wild type. Re-introduction of OsGS1;1 cDNA under the control of its own promoter into the mutants successfully complemented these phenotypes. Progeny where Tos17 was heterozygously inserted or deleted during segregation showed normal phenotypes. The results indicate that GS1;1 is important for normal growth and grain filling in rice; GS1;2 and GS1;3 were not able to compensate for GS1;1 function.

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Section: Discussionsupporting

confidence: 82%

Severe reduction in growth rate and grain filling of rice mutants lacking OsGS1;1, a cytosolic glutamine synthetase1;1

et al. 2005

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“…In addition, this finding reinforces the current consensus that each individual GS gene product in a given plant species may play a specific role during plant growth and development (Cren and Hirel, 1999). In maize, it has been previously shown that the five members of the cytosolic GS multigene family may be differentially expressed in different organs including roots and leaves (Sakakibara et al, 1992b;Li et al, 1993) and developing seeds (Rastogi et al, 1998). It has also been demonstrated that, at least in vegetative organs, the source of N may be an additional factor that may modulate their transcription (Sakakibara et al, 1992a).…”

Section: Genetic Analysis Of N Metabolism In Relation To Maize Kernelmentioning

confidence: 99%

“…Although this has never been fully demonstrated, it has been proposed by several authors that each cytosolic GS isoenzyme plays a specific physiological role suited to the physiological need of the plant (Woodall et al, 1996;Cren and Hirel, 1999). This may explain why seed-specific GS1 isoenzymes are differentially expressed during certain phases of seed development (Rastogi et al, 1998).…”

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confidence: 99%

Genetic and Physiological Analysis of Germination Efficiency in Maize in Relation to Nitrogen Metabolism Reveals the Importance of Cytosolic Glutamine Synthetase

Limami¹,

Rouillon²,

Glévarec³

et al. 2002

Plant Physiol.

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We have developed an approach combining physiology and quantitative genetics to enhance our understanding of nitrogen (N) metabolism during kernel germination. The physiological study highlighted the central role of glutamine (Gln) synthetase (GS) and Gln synthesis during this developmental process because a concomitant increase of both the enzyme activity and the amino acid content was observed. This result suggests that Gln is acting either as a sink for ammonium released during both storage protein degradation and amino acid deamination or as a source for amino acid de novo synthesis by transamination. In the two parental lines used for the quantitative genetics approach, we found that the increase in Gln occurred earlier in Io compared with F 2 , a result consistent with its faster germinating capacity. The genetic study was carried out on 140 F6 recombinant inbred lines derived from the cross between F 2 and Io. Quantitative trait locus mapping identified three quantitative trait loci (QTLs) related to germination trait (T50, time at which 50% of the kernels germinated) that explain 18.2% of the phenotypic variance; three QTLs related to a trait linked to germination performance, kernel size/weight (thousand kernels weight), that explain 17% of the phenotypic variance; two QTLs related to GS activity at early stages of germination that explain 17.7% of the phenotypic variance; and one QTL related to GS activity at late stages of germination that explains 7.3% of the phenotypic variance. Coincidences of QTL for germination efficiency and its components with genes encoding cytosolic GS (GS1) and the corresponding enzyme activity were detected, confirming the important role of the enzyme during the germination process. A triple colocalization on chromosome 4 between gln3 (a structural gene encoding GS1) and a QTL for GS activity and T50 was found; whereas on chromosome 5, a QTL for GS activity and thousand kernels weight colocalized with gln4, another structural gene encoding GS1. This observation suggests that for each gene, the corresponding enzyme activity is of major importance for germination efficiency either through the size of the grain or through its faster germinating capacity. Consistent with the possible nonoverlapping function of the two GS1 genes, we found that in the parental line Io, the expression of Gln3 was transiently enhanced during the first hours of germination, whereas that of gln4 was constitutive.Seeds are complex structures consisting anatomically and genetically of three parts: the embryo, the endosperm, and the seed coat. During their development, seeds are supplied by the mother plant with assimilates. From a physiological point of view, seeds behave as sink organs accumulating C and N metabolites stored as starch, proteins, amino acids, or lipids. C and N metabolism in developing seeds has been extensively studied in various monocot species, i.e. maize (Zea mays) and wheat (Triticum aestivum), as well as dicot species, i.e. pea (Pisum sativum), soybean (Glycine max), and alfalfa ...

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“…The GS 1‐2 gene encodes an isozyme of glutamine synthetase that is strongly expressed in the pedicel of developing maize seeds (Rastogi et al 1998) and whose promoter is capable of driving gene expression exclusively in the maternal tissues of developing seeds of transgenic maize plants (Muhitch et al 2002). Here, the effects of truncation from the 5′ end of the upstream region of the promoter were examined on transgene expression.…”

Section: Discussionmentioning

confidence: 99%

“…The GS 1-2 gene encodes an isozyme of glutamine synthetase that is strongly expressed in the pedicel of developing maize seeds (Rastogi et al 1998) and whose promoter is Table 1. Efficiency of transformation of maize with GS 1-2 /GUS heterologous gene promoter deletion series.…”

Section: Discussionmentioning

confidence: 99%

Transformation efficiencies and expression patterns of a series of truncated GS_1‐2 promoter/GUS transgenes in maize

Muhitch¹,

Liang

Sollenberger

2003

Physiologia Plantarum

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One isoform of maize glutamine synthetase, encoded by GS1‐2, is localized exclusively in the maternal tissues of the developing kernel. Previously, we have demonstrated the ability of the proximal 664 base pair 5′ upstream portion of GS1‐2 to drive maternal tissue‐specific GUS expression in transgenic maize kernels (Muhitch et al. Plant Sci. 163: 865–872). In this report, a series of GS1‐2 promoter/GUS reporter transgenes, progressively truncated from the 5′ end of the full length 664 base pair promoter, were evaluated for transformation efficiency and their ability to drive tissue‐specific gene expression in transgenic maize. Analysis of transgene integration and expression suggests that GS1‐2/GUS transgenes were incorporated efficiently into the maize genome, but were not expressed efficiently in maize cells. Truncation of the promoter from −664 to −394, −206 or −72, relative to the putative transcription start site, resulted in the loss of tissue specific expression within the kernels of transformed plants. Among the truncated series, moderate staining was exhibited by the −394 promoter/GUS gene transformants, stronger staining was found in −206 promoter/GUS gene transformants, but relatively weak and variable staining occurred in plants transformed with the −72/GUS gene. Likely explanations for these observations are considered.

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The Maize Glutamine Synthetase GS1- Gene is Preferentially Expressed in Kernel Pedicels and is Developmentally-Regulated

Cited by 24 publications

References 21 publications

Severe reduction in growth rate and grain filling of rice mutants lacking OsGS1;1, a cytosolic glutamine synthetase1;1

Severe reduction in growth rate and grain filling of rice mutants lacking OsGS1;1, a cytosolic glutamine synthetase1;1

Genetic and Physiological Analysis of Germination Efficiency in Maize in Relation to Nitrogen Metabolism Reveals the Importance of Cytosolic Glutamine Synthetase

Transformation efficiencies and expression patterns of a series of truncated GS_1‐2 promoter/GUS transgenes in maize

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The Maize Glutamine Synthetase GS1- Gene is Preferentially Expressed in Kernel Pedicels and is Developmentally-Regulated

Cited by 24 publications

References 21 publications

Severe reduction in growth rate and grain filling of rice mutants lacking OsGS1;1, a cytosolic glutamine synthetase1;1

Severe reduction in growth rate and grain filling of rice mutants lacking OsGS1;1, a cytosolic glutamine synthetase1;1

Genetic and Physiological Analysis of Germination Efficiency in Maize in Relation to Nitrogen Metabolism Reveals the Importance of Cytosolic Glutamine Synthetase

Transformation efficiencies and expression patterns of a series of truncated GS1‐2 promoter/GUS transgenes in maize

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Transformation efficiencies and expression patterns of a series of truncated GS_1‐2 promoter/GUS transgenes in maize