Related Experiment Videos
Intercellular localization of nitrate reductase in roots.
T W Rufty1, J F Thomas, J L Remmler
1United States Department of Agriculture, Agricultural Research Service, Oxford, North Carolina 27565.
Plant Physiology
|November 1, 1986
Summary
Corn root cells show nitrate reductase (NR) is mainly in epidermal cells, not throughout the root symplastic pathway. This suggests limited nitrate reduction occurs in inner root cells during transport.
Area of Science:
- Plant Physiology
- Molecular Biology
- Biochemistry
Background:
- Nitrate reductase (NR) is a key enzyme in nitrate assimilation.
- Understanding NR compartmentalization in plant roots is crucial for nutrient uptake and transport.
- The root symplastic pathway facilitates nutrient movement within the plant.
Purpose of the Study:
- To investigate the cellular localization of nitrate reductase (NR) in corn roots.
- To determine if NR is compartmentalized within specific cell types of the root symplastic pathway.
- To explore the implications of NR distribution for nitrate reduction during transport.
Main Methods:
- Microsurgical separation of corn root cells into epidermis, cortex, and stele.
- In vitro assays to detect nitrate reductase (NR) activity.
- Enzyme-linked immunosorbent assays (ELISA) to quantify NR presence.
Main Results:
- Nitrate reductase (NR) was predominantly found in epidermal cells, even at high nitrate concentrations.
- Low nitrate levels (0.2 mM) resulted in NR detection almost exclusively in epidermal cells.
- Higher nitrate levels (20.0 mM) showed NR in all cell groups, but still concentrated in epidermal cells.
Conclusions:
- Nitrate reduction is largely restricted to the epidermis in corn roots.
- Cortical and stelar cells exhibit limited capacity to induce NR and reduce nitrate.
- Potential mechanisms include insensitivity to nitrate induction, limited uptake by inner cells, or symplastic compartmentalization of nitrate.