Plant mechanisms of siderophore-iron utilization

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6717584

Crowley, D E

Mechanisms of siderophore iron-utilization by plants were examined to determine whether plants have direct mechanisms for acquiring iron from microbially-produced hydroxamate siderophores or simply take up inorganic iron in equilibrium with the chelate (shuttle mechanism). Experiments were designed to determine whether the monocot plant species, oat (Avena sativa L. cv. Victory) could acquire iron from ferrichrome under hydroponic conditions in which iron uptake was most likely to occur by direct use of the chelating agent. Ten-day-old iron-deficient seedlings, grown in aerated Hoagland's nutrient solution (minus iron) buffered at pH 7.4 with CaCO/sub 3/, were placed in fresh nutrient solution containing 10/sup -7.4/M radioactive /sup 55/FeCl/sub 3/ (23.7 mCi/mg) with the synthetic chelate, EDDHA (10..pi../sup 5/M), ferrichrome (10/sup -5/M), or with no chelate. After 6 days, shoot content of /sup 55/Fe in shoots of plants provided with ferrichrome was 100-fold greater than that in shoots of plants provided with EDDHA. Therefore iron uptake by oat under these conditions not only indicates direct use of ferrichrome, but also suggest that oat may be better able to acquire iron from siderophores than from synthetic chelates. One possible mechanism for direct use of chelating agents, may involve siderophore binding sites on the plasmalemma of root cortical cells where iron is split from the chelate by enzymatic reduction of ferric to ferrous iron. To demonstrate hypothesized siderophore binding sites on oat roots, experiments examined possible competition for presumed siderophore binding sites by an inert analog of ferrichrome constructed by irreversible chelation with chromium.

• Research Organization: Colorado State Univ., Fort Collins (USA)
• OSTI ID: 6717584
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BETA DECAY RADIOISOTOPES
CEREALS
CHELATING AGENTS
CHLORIDES
CHLORINE COMPOUNDS
ELECTRON CAPTURE RADIOISOTOPES
EVEN-ODD NUCLEI
GRASS
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
IRON 55
IRON CHLORIDES
IRON COMPOUNDS
IRON ISOTOPES
ISOTOPES
METABOLISM
NUCLEI
OATS
PLANTS
RADIOISOTOPES
ROOTS
SEEDLINGS
TRANSITION ELEMENT COMPOUNDS
UPTAKE
YEARS LIVING RADIOISOTOPES