A Microelectrode Study of Oxygen Distribution in the Roots of Intact Maize Seedlings
A preliminary platinum microelectrode study of radial oxygen distribution in roots is described. Roots of intact maize seedlings were embedded in solid agar to impede the radial oxygen supply and ensure that there was a substantial dependence upon cortical gas-phase diffusion from the shoot. Radial oxygen profiles were measured at various positions along the roots using platinum microelectrodes driven through the agar and into the root, mostly in 5μm steps, by a servo-operated piezoelectric microdriver. Any damage caused by the electrodes appeared to be very localised and there was no evidence that it greatly affected the oxygen regimes. In general, the profiles were in good agreement with earlier mathematical modelling predictions of oxygen distribution in roots and, by adjustment of shoot oxygen concentrations, some anoxia could be induced readily within the stele, while the cortex remained aerobic. Interestingly, whilst the meristematic region of the growing root appeared to be aerobic throughout, much of the root cap and some of the root cap material ensheathing the meristematic region were found to be anoxic.
KeywordsPrimary Root Oxygen Distribution Meristematic Region Root Aeration Oxygen Profile
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