Arbuscular Mycorrhizal Fungus Diversispora spurcum Improved the Growth and Freeze Tolerance of Mongolian Crested Wheatgrass (Agropyron cristatum)
Authors：Burenjargal Otgonsuren, Ming-Jen Lee
Key words：Agropyron cristatum, Arbuscular mycorrhiza, Diversispora spurcum, freeze tolerance,growth.
Agropyron cristatum (L.) Gaertn. (crested wheatgrass) is an endemic grass species, which
dominates the Mongolian steppe. In this study, spores of arbuscular mycorrhizal fungi (AMF) in
the rhizosphere soil of crested wheatgrass were isolated with wet-sieving/decanting methods and
sucrose density gradient centrifugation, and the associated species was identified as Diversispora
spurcum C. Walker & Schuessler. An arbuscular-mycorrhizal resynthesis experiment showed that
D. spurcum formed arbuscular mycorrhizae with crested wheatgrass seedlings, and promoted their
growth and biomass. The dependency of the crested wheatgrass on arbuscular mycorrhizae (AMs)
with D. spurcum was 292%. Diversispora spurcum inoculation also significantly increased the
nitrogen and mineral (P, K, Ca, Mg, and Na) contents in roots, stems, and leaves of crested wheatgrass.
Inoculated and non-inoculated crested wheatgrass seedlings were cold-acclimated and subsequently
subjected to freeze tolerance tests at -8, -11, -14, -15, -16, and -17℃, respectively. The
leaf lethal temperatures for 50% mortality (LT50) of non-inoculated and inoculated crested wheatgrass
were -8 and -14℃, respectively, while the whole plant LT50 values of non-inoculated and
inoculated crested wheatgrass were -11 and -15.5℃, respectively. These results demonstrated that D.
spurcum could effectively form arbuscular mycorrhizae with crested wheatgrass and improve its
growth, presumably through enhanced nutrition acquisition, and freeze tolerance.