AM or VAM: What’s in a Word?

Abstract

As long ago as 1974, although the use of the term “vesicular-arbuscular mycorrhizas (VAM)” was commonly used, it was recognized that some of the fungi that formed mycorrhizas with arbuscules did not produce vesicles in the roots of plants. It was therefore proposed that the more general term, “arbuscular mycorrhiza (AM)” should be used to describe the mycorrhizas formed between plants and species of fungi then placed in the Endogonaceae (Daft and Nicolson 1974). Subsequent studies and observations have confirmed that members of the genera Scutellospora and Gigaspora form mycorrhizas with arbuscules, but not with vesicles, and it seems unlikely that they possess such a capability. Smith (Chap. 1, this Vol.) has argued strongly for retaining the former term (VAM), rather than changing a commonly used practice. Curiously, she supports this reasoning by suggesting that VAM is “... a more general term” — precisely the same argument used by the earlier authors to support their proposals. She also argues that, because “... most [sic] plant biologists ... are familiar with the term VAM, and that people in ... non-specialist circles ... also use this terminology, a change to AM is likely to cause confusion and uncertainty ...”