Naturwissenschaften 77, 388 - 389 (1990) © Springer-Verlag 1990

Growth-Promoting Effect of a Brassinosteroid

in Mycelial Cultures of the Fungus Psilocybe cubensis

J. Gartz

Institut fur Biotechnologie der AdW der DDR, DDR-7050 Leipzig

G. Adam and H.-M. Vorbrodt

Institut fur Biochemie der Pflanzen der AdW der DDR, DDR-4010 Halle/S.

Brassinosteroids represent a new class

of steroidal plant-growth regulators re-

garded from several laboratories as a

further group of phytohormones. Till

now about 30 members have been de-

tected in a wide variety of higher plants

including Angiospermae and Gymno-

spermae 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 bras-

sinosteroid 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 sub-

strates [6]. The cultivation of the myce-

lium 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 in-

fluence of 10-2 ppm brassinosteroid on

growth of the fungus was investigated

(ten runs each). In the experiments with

agar we observed that growth of my-

celia took place two to three times

Fig. 1. Structure of 22S,23S-homobrassi-

nolide

faster than in the control series without

steroid. In the dung/grain substrate the

first flush of fruit bodies appeared re-

markably earlier. Thus, whereas in the

control the first sporocarps were

produced within 4 to 5 weeks, the addi-

tion of the brassinosteroid caused a

fruiting of the mycelia already in 3 to

3.5 weeks. Furthermore, a variation of

the number of formed fruit bodies in

the five flushes during fructification

was observed, e.g., with brassino-

steroid four to seven mushrooms were

produced in the first flush compared to

one to three in the control (Fig. 2). The

steroid-treated cultures afforded also a

remarkably higher dry mass than the

control cultivations (3.4 — 3.9 g versus

2.3-2.9 g/10 g substrate). The forma-

tion of incomplete fruit bodies, nor-

mally present in mushroom cultivation,

was almost completely suppressed by

the brassinosteroid. Interestingly, the

added brassinosteroid also influenced

the morphology of the formed fruit

bodies which lacked the typical mem-

branous annulus on the stems.

In summary, the observed strong

growth-promoting effect of 22S.23S-

homobrassinolide in mycelial cultures

of Psilocybe cubensis suggests that

brassinosteroids could also play a phys-

Fig. 2. Fruit bodies of Psilocybe cubensis on dung/grain substrate, a) Five weeks after in-

oculation, b) with 22S,23S-homobrassinolide 3 weeks after inoculation

iological role in higher fungi. Further

studies, including commercially im-

portant species, are in progress.

Received May 2, 1990

l.Yokota, T., Takahashi, N., in: Plant

Growth Substances, p. 129 (M. Bopp,

ed.). Heidelberg: Springer 1986

2. Adam, G., Marquardt, V.: Phytochemis-

try25, 1787(1986)

3. Meudt, W. J.: ACS Symp. Ser. 325, 53

(1987)

4. Maught, T. H.: Science212, 33 (1981)

5. Hamada, K.: FFTC Book Ser. 34, 188

(1986)

6. Gartz, J.: Biochem. Physiol. Pfl. 184,

337 (1989); J. Basic Microbiol. 29, 347

(1989)