The Growth-Promoting Effect of Indole-3-Acetic Acid on the Common Cultivated Mushroom, Psalliota Hortensis (Cooke) Lange Forma Albida Lange

Abstract

SummaryA strain of the white-capped form of the common cultivated mushroom, Psalliota hortensis (Cook;e,} Lange forma albida Lange, appeared unable to grow appreciably on a liquid basal medium which contained glucose, asparagine, and mineral salts. Addition of thiamin and biotin increased the growth a little . . A number of other vitamins were without effect. Indole-3-acetic acid (IAA) in concentrations of from 5 to 100 mg/l markedly increased growth, particularly in the presence of thiamin and biotin, but only when the inoculum was floating on the surface of the culture medium. If the inoculum was submerged, addition of IAA had very little effect. The growth of both floating and submerged inocula was markedly increased by the addition of yeast extract, cotton wool extract, or mushroom compost extract, although these did not appear to contain appreciable quantities of IAA.The fungus grew fairly well on basal medium solidified with agar which had been purified to remove vitamins. Addition of thiamin or biotin did not promote growth. Concentrations of lAA of 10 and 100 mg/l almost completely prevented initial growth while concentrations of 0.001, 0.1, and 1.0 mg/l were without effect. However, after about 30 days vigorous growth commenced in the medium originally containing 10 mg/l IAA and proceeded at the same rate as in its absence. It seems probable that this was due to inactivation of the lAA by the small amount of mycelium formed.It is suggested that IAA may play a part in the growth processes of this fungus similar to that in higher plants, although the possibility that some related substance siIch as tryptophane is required for growth must also be considered, particularly in view of the unidentified growth-promoting factor present in various extracts.

Effect of Indole‐3‐Acetic Acid on the Formation of Oxidases in Fungi

“…The growth of P. versicolor and M. .scorodonius was only slightly affected hy moderate IAA concentrations (Tables 2-4). Growth stimulations of fungi hy IAA have heen reported to occur (for references, see Fraser 1953), hut no definite conclusions as to the mechanism have heen reached. No similarity between the well-known effects of IAA on higher plants and the growth response of fungi can he said to exist.…”

Aromatic Compounds as Growth Substances for Laccase‐producing Rot Fungi

“…There are reports in the lilerature that also auxins have a growth-promoting effect on some fungi. Fraser (17) foinid such au effect of indole 3-acetic acid (c. 10~^ .1/) on the common cultivatetl mushi'oom. Psfdliola hortenais, if it was grown as surface mycelium iu liquid cultures.…”