PLANT HORMONES IN FUNGI AND BACTERIA FROM MALTING BARLEY

Abstract

40 Fungi and 16 strains of bacteria, isolated from the grains of three cultivars of malting-grade barley (Kymppi, Pokko and Kustaa, of 1990 harvest), were screened for the production of the plant hormones gibberellic acid (GA 3 ), abscisic acid (ABA) and indole-3-acetic acid (IAA). Four fungal strains were found capable of GA 3 production and four of ABA production. IAA production was common among both fungi (58% of strains active) and bacteria (88% of strains active). To get an estimate of the physiological significance of the presence of plant hormone producing microbes, the plant hormone production per microbial unit in the liquid growth media of the cultured organisms was weighed against the microbial counts and the endogenous hormone concentrations of barley grains. It was concluded that bacterial IAA production could be of significance in imbibed grains. This presupposes, however, that the conditions be ideal for the propagation of the active species and also, for the production of IAA by those same species and lastly, that similar production occurs in vivo as well as in vitro. Microbial GA 3 and ABA production, on the other hand, were estimated to occur in negligent amounts.