Presentation Title

Plant Glutaredoxin AtGRX660 Controls Root and Shoot Development

Faculty Mentor

Matthew Escobar

Start Date

23-11-2019 12:45 PM

End Date

23-11-2019 1:00 PM

Location

Markstein 103

Session

oral 3

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Glutaredoxins (GRXs) are small oxidoreductase enzymes that can reduce disulfide bonds in target proteins. The genome of the model plant Arabidopsis thaliana has more than 30 GRX genes, but the biological function of most of these GRXs is unknown. We previously found that a small group of Arabidopsis GRX genes is specifically activated by nitrate, a common source of nitrogen in the soil. In order to better characterize the function of one of these nitrate-regulated GRXs, AtGRX660, we generated transgenic Arabidopsis plants that continuously overexpress the AtGRX660 gene. We isolated RNA from 12 independent transgenic lines and quantified AtGRX660 mRNA levels via real-time reverse transcriptase PCR. Three elite lines displaying >100-fold increase in basal AtGRX660 transcript levels were selected for further analysis. AtGRX660-overexpression lines and wild-type plants were grown on soil in a controlled environment growth chamber for characterization of shoot phenotypes, and on vertically-orientated plates of plant growth media for characterization of root phenotypes. All AtGRX660-overexpression lines displayed a dwarf shoot phenotype, with significant reductions in shoot biomass, total leaf area, and silique length compared to wild-type plants. In addition, root system architecture was highly altered. While primary root growth was normal in the transgenic plant lines, lateral roots were almost completely absent. Phase contrast microscopy demonstrated that lateral root primordia develop in the transgenic lines, but these primordia do not elongate and emerge from the primary root. Overall, these results suggest that AtGRX660 acts a negative regulator of shoot organ development and inhibits lateral root elongation. Our findings could have agricultural relevance in plant drought tolerance, since AtGRX660 differentially affects primary root system growth (root system depth) and lateral root system growth (root system breadth).

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Nov 23rd, 12:45 PM Nov 23rd, 1:00 PM

Plant Glutaredoxin AtGRX660 Controls Root and Shoot Development

Markstein 103

Glutaredoxins (GRXs) are small oxidoreductase enzymes that can reduce disulfide bonds in target proteins. The genome of the model plant Arabidopsis thaliana has more than 30 GRX genes, but the biological function of most of these GRXs is unknown. We previously found that a small group of Arabidopsis GRX genes is specifically activated by nitrate, a common source of nitrogen in the soil. In order to better characterize the function of one of these nitrate-regulated GRXs, AtGRX660, we generated transgenic Arabidopsis plants that continuously overexpress the AtGRX660 gene. We isolated RNA from 12 independent transgenic lines and quantified AtGRX660 mRNA levels via real-time reverse transcriptase PCR. Three elite lines displaying >100-fold increase in basal AtGRX660 transcript levels were selected for further analysis. AtGRX660-overexpression lines and wild-type plants were grown on soil in a controlled environment growth chamber for characterization of shoot phenotypes, and on vertically-orientated plates of plant growth media for characterization of root phenotypes. All AtGRX660-overexpression lines displayed a dwarf shoot phenotype, with significant reductions in shoot biomass, total leaf area, and silique length compared to wild-type plants. In addition, root system architecture was highly altered. While primary root growth was normal in the transgenic plant lines, lateral roots were almost completely absent. Phase contrast microscopy demonstrated that lateral root primordia develop in the transgenic lines, but these primordia do not elongate and emerge from the primary root. Overall, these results suggest that AtGRX660 acts a negative regulator of shoot organ development and inhibits lateral root elongation. Our findings could have agricultural relevance in plant drought tolerance, since AtGRX660 differentially affects primary root system growth (root system depth) and lateral root system growth (root system breadth).