Activity of some glycolytic and pentose phosphate pathway enzymes during the development of adventitious roots

Activities of phosphofructokinase (PFK, EC 2.7.1.11), glyceraldehyde 3‐phosphate (NAD) dehydrogenase [G‐3‐PD(NAD), EC 1.2.1.12], glucose 6‐phosphate dehydrogenase (G‐6‐PD, EC 1.1.1.49), and 6‐phosphogluconate dehydrogenase (6‐PGD, EC 1.1.1.44) were determined in bean cuttings ( Phaseolus vulgaris L. cv. Top Crop) over 4 days, encompassing adventitious root primordium initiation and development. Effects of applied auxin and “endogenous root‐forming stimulus”(ERS) on enzyme activities, concentrations of reducing sugars, and primordium development were also determined during the first 4 days of propagation. Effects of auxin were determined through use of applied indole‐3‐acetic acid (IAA) or 2,3,5‐triiodobenzoic acid. Effects of ERS were evaluated by means of decapitation of cuttings. Increased basipetal transport and increased metabolism of reducing sugars occurred in leafy cuttings in response to applied IAA and to ERS. Primordium development and activities of the four enzymes increased in leafy cuttings under conditions that simultaneously increased basipetal transport and metabolism of reducing sugars. Three types of enzyme activity response were found: (i) activity increased over time by ERS and by applied IAA [G‐3‐PD(NAD)], (ii) activity increased over time by ERS but not by applied IAA (PFK, G‐6‐PD), (iii) activity increased over time but not by ERS or applied IAA (6‐PGD). Increases in G‐3‐PD(NAD), G‐6‐PD, and PFK activity in leafy cuttings were positively related to primordium development. 6‐PGD activity increased in leafy cuttings during primordium development and may have supported it. However, equal increases occurred in decapitated cuttings, in which the long‐term development of primordia was supressed. Results for G‐3‐PD(NAD) that were obtained in an experiment with jack pine ( Pinus banksiana Lamb.) seedling cuttings were similar to results for the same enzyme in bean cuttings. G‐3‐PD(NAD) activity in naphthaleneacetic acid‐treated jack pine cuttings increased with time, in comparison with untreated cuttings, before root emergence.