Relations of respiration and growth in the Avena coleoptile

Abstract

The respiration of Avena coleoptile sections suspended in a sucrose-phosphate solution may be increased by additions of organic acids such as succinate, or by additions of adenylic acid, arginine, or IAA. The increases due to the latter three substances are not additive among themselves, but all are additive to the increase occasioned by succinate. Dinitrophenol (DNP) in a concentration which essentially completely inhibits section growth is a powerful promoter of Avena section respiration. In the presence of DNP, the effects of adenylic acid, arginine, and IAA are suppressed. Since DNP is known to act as an agent for uncoupling of high energy phosphate transfer from the respiratory oxidations, it is suggested a, that available phosphate acceptors may limit respiratory rate of Arena sections, and b, that adenylic acid, arginine, and IAA may promote respiration by functioning in phosphate transfer. Di-chloranisole (DCA), an antagonist of IAA, does not inhibit the endogenous respiration of IAA depleted sections. It does inhibit the increase in respiration due to IAA. DCA does not affect the increases due to adenylic acid or arginine. Canavanine, an antagonist of arginine, inhibits the increase of respiration clue to IAA but not that clue to adenylic acid. Canavanine in a concentration which completely inhibits growth inhibits ca. 15 per cent of the endogenous respiration of Arena coleoptile sections. On the basis of the use of the inhibitors DNP, canavanine and DCA, it is concluded that the reactions here considered are involved in Arena section growth and respiration in the following order...

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