Annette Hervey

Studies on fungi cultivated by ants

A collection of 36 fungi cultivated by leaf-cutting ants has been established at The New York Botanical Garden. These fungi grow on a variety of natural media and on a synthetic medium with mineral salts, dextrose, casein hydrolysate, purine and pyrimidine bases and vitamins. Tests of the fungi for antibacterial activity were all negative againstStaphylococcus aureus andEscherichia coli. Only four isolates of ant fungi, each cultivated by a different species of ant, produced basidiocarps on oatmeal agar. Taxonomic studies indicate that these belong to the same species of fungus (Lepiota sp.). Eighteen isolates produced bromatia characteristic of the form species,Attamyces bromatificus Kreisel, one produced a mycelium with clamp connections, and thirteen produced sterile mycelia without clamped hyphae and without bromatia.

Antibiotic metabolite of a fungus cultivated by gardening ants.

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Light and the development of Poria ambigua.

In the course of investigations on the nutrition of some of the Basidiomycetes, it was noted that a culture of Poria ambigua Bres. from Ross W. Davidson, his number 86357, formed basidiospores in the light but produced few or none in the dark. The influence of light on the development of many fungi is well known and an extensive literature on the subject exists which will not be reviewed here. Our preliminary observations indicated that Poria ambigua in its response to light might be an especially favorable subject for investigation. Methods and Materials.-The basal medium 1 employed contained mineral salts, dextrose, casein hydrolysate, various purine and pyrimidine bases and the known B vitamins. The hydrion concentration was approximately pH 4.5. Cultures were grown in triplicate or quintuplicate at 25? C in 20 x 100 mm petri dishes containing 20 ml of medium, solidified with 1.5 per cent Difco agar or in 125 ml Erlenmeyer flasks which contained 25 ml of liquid medium. Our standard inoculum was obtained from colonies which had grown three or four days at 25? in the dark. Inoculum, unless otherwise stated, consisted of bits of mycelium 1 mm or 5 mm in diameter taken 3 or 4 mm from the edge of the colony by the method described by Yusef (1953). After inoculation, the dishes were wrapped individually in aluminum foil and incubated in a light-tight incubator at 25?. Unless otherwise indicated, the light to which cultures were exposed was a mixture of diffuse daylight and artificial light totaling from 200 to 280 foot-candles (ft-c). Natural Materials and Growth.-Poria ambigua grew in our basal medium. However, growth of the fungus as measured by dry weight

DEVELOPMENT OF PLANTS FROM LEAF DISCS OF VARIEGATED COLEUS AND ITS RELATION TO PATTERNS OF LEAF CHLOROSIS

SummaryLeaf discs approximately 8 mm in diameter taken from green and from chlorotic areas of variegated leaves ofColeus were grown in light under sterile conditions in a mineral salt, sucrose, vitamin medium supplemented with auxin and cytokinin. Green shoots, which later formed roots, grew from both green and chlorotic discs in media containing suitable amounts of auxin and cytokinin. None developed in media supplemented with auxin alone or with cytokinin alone. Discs with young plants were transferred to soil. Plants that grew varied widely from those with no chlorosis to those with more chlorosis than the original variety from which the discs were taken. Plants grown from discs taken from green areas of leaves with chlorosis varied in patterns of chlorosis as much as those that grew from discs from chlorotic areas of leaves.