2012 Annual Report 1a.Objectives (from AD-416): Survey grasslands of Mongolia and the western United States for species of Oxytropis, Astragalus and Swainsonia to determine which species and populations contain the toxic alkaloid swainsonine that causes locoweed poisoning in livestock. 1b.Approach (from AD-416): The USDA/ARS Poisonous Plant Lab (PPRL) has developed chemical assays for the toxic alkaloid swainsonine and for detecting and quantifying the endophytic fungus Undifilum which produces swainsonine. Species of Oxytropis, Astragalus and Swainsona will be collected throughout Mongolia and the western United States and small samples of leaf and flower material will be sent to PPRL to determine the presence of the endophyte and concentration of swainsonine. From these samples toxicity of the species will be determined. 3.Progress Report: Locoweeds, species of Oxytropis and Astragalus that contain the toxic alkaloid swainsonine, cause widespread poisoning of livestock in Inner Mongolia. Due to overgrazing and desertification, locoweeds seriously threaten the livestock sustainability and overall health of the vast native grasslands of China. Through a collaborative research effort, scientists at Inner Mongolia Agricultural University in Hohhot China, along with ARS scientists in Logan, UT, detected swainsonine at concentrations greater than 0.01% in Astragalus variabilis and Oxytropis grabra, two common locoweed species in Mongolia. Subsequently, the endophyte, Undifilum was detected in these plant species using cell culture and PCR techniques. Currently, 10 strains of endophyte have been isolated from Oxytropis glabra and 42 strains have been isolated from the multiple Astragalus species growing on the grasslands of China. Eleven of these strains have been shown to produce swainsonine and are potentially high risk for poisoning to livestock.