Comparison of the Respiratory Metabolism of Plantago lanceolata L. and Plantago major L.

Bryce, J. H. and ap Rees, T. 1985. Comparison of the respiratory metabolism of Plantago lanceolata L. and Plantago major L.—J. exp. Bot. 36: 1559-1565. The aim of this work was to discover if the respiratory metabolism of the roots of Plantago lanceolata L. differed from that of the roots of Plantago major L. Measurements of oxygen uptake and dry weight of excised root systems during growth of seedlings provided evidence that the two species differed in the amount of respiration needed to support a given increase in dry weight. Excised root systems were given a 6-h pulse in [U-14C]sucrose followed by a 16-5-h chase in sucrose. The detailed distribution of 14C amongst the major components of the roots at the end of the pulse and the chase revealed no significant difference between the two species. Patterns of 14C02 production from [1-I4C], [2-14C], [3,4-14C], and [6-14C]glucose of excised root systems from plants of three ages were similar for the two species. It is suggested that there is no conclusive evidence for any significant inherent difference in the respiratory metabolism of the roots of the two species. Key words—liC sugar metabolism, respiration, roots, Plantago. Correspondence to: Botany School, University of Cambridge, Downing Street, Cambridge CB2 3EA, U.K.