NUTRITIONAL REQUIREMENTS OF ORCHID ENDOPHYTES

Abstract

Four geographically distinct isolates of Tulasnella calospora (Bourdier) Juel exhibited a similar nutritional pattern and utilized a wide range of carbon compounds including cellulose. None would grow on a mineral salts/glucose medium unless undefined materials were present. Growth occurred when a mixture of ten amino acids and ten vitamins was used, and all four isolates were heterotrophic for thiamine and p‐amino benzoic acid. They were also exacting for nitrogen. Growth on ammonium ions was very limited but asparagine, glycine and urea were good nitrogen sources while glutamine, arginine and alanine were less adequate. Isolates of Ceratobasidium cornigerum (Bourd.) Rogers and a Rhizoctonia sp. were self‐sufficient for vitamins and grew well on nitrate or other nitrogen sources tested. They were more efficient than Tulasnella calospora isolates in their nitrogen economy. T. calospora isolates may obtain vitamins and nitrogen compounds from their orchid hosts and may exhibit a limited phase of biotrophic nutrition. Copyright © 1978, Wiley Blackwell. All rights reserved