Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/1996
Publication Date: N/A
Interpretive Summary: Interpretive Summary not needed for this 115.
Technical Abstract: Two unique mutations (dgl and brz) have been previously identified in pea, which result in extreme Fe over-accumulation when plants are supplied normal levels of Fe. Leaf Fe concentrations can reach 5,000-10,000 ug/g DW in mutants, relative to 100-300 ug/g DW in wildtype (WT) pea (cv. Sparkle). The brz and dgl mutants have been shown to exhibit elevated rates of root Fe(III) reductase activity when grown on Fe, thus enabling excess influx of Fe2+. The elevated rates are stimulated by an unidentified shoot signal. Previous phenotypic evaluation (leaf Fe content) of F1 progeny of WT x mutant or mutant x mutant has suggested that both mutant genes are semi-dominant; intermediate leaf Fe concentrations were found in F1 plants (grown in vermiculite), relative to WT or homozygous mutants. We have recently re-examined similar F1 plants (grown hydroponically) by evaluating their root Fe(III) reductase activity at d 15. Surprisingly, all l+Fe-treated (2 uM FeEDDHA) F1 plants exhibited low rates of root Fe(III) reductase activity, equal to that of the WT. Reductase rates were enhanced by Fe-deficiency in all F1 plants. The discrepancy between reductase rates and leaf Fe concentrations may be due to different growth conditions in the two studies, and potential size differences of the root systems. A model will be presented incorporating shoot signals and root size to explain the effects of these mutations. This research was funded in part by USDA-ARS Coop. Agr. No. 58-6250-1-003 and USDA-CSRS Grant No. 94-37100-0823.