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.
KeywordsPorosity Maize Agar Platinum Respiration
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- Armstrong W (1979) Aeration in higher plants In: Advances in botanical research Vol. 7. Academic Press, pp 225–332Google Scholar
- Armstrong W (1988) Aeration in roots. In: Cherry T (ed) Environmental stress physiology, NATO ASI series, Vol. G19. Springer-Verlag, Berlin, Germany, pp 197–206Google Scholar
- Armstrong W, Beckett PM (1987) Internal aeration and the development of stelar anoxia in submerged roots: A multishelled mathematical model combining axial diffusion of oxygen in the cortex with radial losses to the stele, the wall layers and the rhizosphere. The New Phytologist 105: 221–245CrossRefGoogle Scholar
- Armstrong W, Beckett PM, Justin SHFW, Lythe S (1990) Modelling and other aspects of root aeration. In: Jackson MB, Davies DD, Lambers H (eds) Plant life under oxygen stress, SPB Academic, The Hague, The Netherlands, pp 267–282Google Scholar
- Cringle SJ, Yu D-Y, Alder VA (1990) Intraretinal and intravitreal oxygen distribution in the rat. Advances in Experimental Medical Biology - Oxygen Transport to Tissue XIIIGoogle Scholar
- Hook DD, McKevlin MR (1988) Use of oxygen microelectrodes to measure aeration in the roots of intact tree seedlings. In: Hook DD, McKee WH Jr, Smith HK, Gregory J, Burrell VF Jr, Devoe MR, Sojka RE, Gilbert S, Banks R, Stolzy LH, Brooks C, Matthews TD, Shea TH (eds) The ecology and management of wetlands, Timber Press, Portland, Oregon, USA, pp 467–476Google Scholar