EVIDENCE FOR DIFFUSION BEING THE MECHANISM OF TRANSLOCATION IN THE HYPHAE OF 3 MOLDS

Translocation of nutrients from a part of the mycelium exposed to an ample supply of a particular nutrient to other parts of the mycelium might be of the utmost importance for the proliferation of fungi in a nutritionally heterogeneous environment. The extent and mechanism of such translocation for saprophytic molds are poorly understood. In this study, diffusion has been shown to be responsible for the translocation of label added as [14C]glucose and [32P[orthophosphate to cultures ofRhizopus nigricans grown on opposing gradients of glucose and other nutrients in glass fiber filters. Translocation of the labeled nutrient was found when the label was added to the side of the mycelium that was exposed to high levels of the nutrient. When added to the inoculation point or to the side of the colony exposed to low levels of the nutrient, the labeled compound was immobilized by the mycelium at the addition point. Translocation was bidirectional in that14C was translocated simultaneously in the opposite direction to32P. A sink for the translocated nutrients was apparent in the region of sporulation. This pattern of translocation of label added as [14C]glucose to the glucose surplus side was similar forTrichoderma viride andStemphylium sp. © 1991 Academic Press, Inc.