FUNGAL ROOT ENDOPHYTES IN FOURWING SALTBUSH, ATRIPLEX-CANESCENS, ON ARID RANGELANDS OF SOUTHWESTERN USA

This research was conducted to determine the nature and incidence of f ungal root endophytes on fourwing saltbush, Atriplex canescens (Pursh) Nutt. Root colter cells of fourwing saltbush in arid rangelands of th e southwestern United States were analyzed and found to be regularly c olonized with three types of endophytic fungi: septate, vesicular-arbu scular mycorrhizae (VAM), and Chytridiomycetes. Septate fungi were 2.7 times more prevalent than VAM and formed intimate non-pathogenic asso ciations characterized by inter- and intracellular hyphae, coils, micr osclerotia, and occasional labyrinthine or ''Hartig net'' structures s imilar to those affiliated with ectendomycorrhizae. External hyphae fo rmed intimate associations with soil and sand particles. Typically, VA M were characterized by hyphae, vesicles, and (at times) coils. VAM we re 2.2 times more prevalent than chytrids. Chytrids were rather common and were expressed as resting and active sporangia found within root cortex cells. The widespread occurrence of these non-destructive funga l associations with plants implies that they have an important role in plant survival in arid environments.