Growth-promoting effect of a brassinosteroid in mycelial cultures of the fungusPsilocybe cubensis

Abstract

Brassinosteroids represent a new class of steroidal plant-growth regulators regarded from several laboratories as a further group of phytohormones. Till now about 30 members have been detected in a wide variety of higher plants including Angiospermae and Gymnospermae as well as in a green alga [1,2]. The strong growth-promoting activity of brassinosteroids involves complex physiological effects, including increase in cell elongation and cell division [3]. Promising results in the application of such compounds to produce higher crop yields and anti-stress effects have also been reported [4, 5]. However, hitherto no studies on occurrence and activity of brassinosteroids on fungi have been published. Here, we report on a strong promoting effect of a brassinosteroid on mycelial growth and fruiting of the subtropical fungus Psilocybe cubensis (Earle) Singer. In our studies an earlier described strain of this fungus was used which is characterized by a high stability in growth and fruiting with various substrates [6]. The cultivation of the mycelium was carried out on 6 % malt agar and a horse dung/rice grain mixture in water was used to produce fruiting. Additionally, the substrates contained 5 g KH2PO4 per 1. As brassinosteroid, synthetic 22S,23S-homobrassinolide (Fig. 1) prepared from stigmasterol (see [2]) was applied. In both cultivation systems the influence of 10 ppm brassinosteroid on growth of the fungus was investigated (ten runs each). In the experiments with agar we observed that growth of mycelia took place two to three times