Host-Species Variation and Environment Influence Endophyte Symbiosis and Mycotoxin Levels in Chinese Oxytropis Species

Abstract

Oxytropis plants are widely distributed in the grasslands in northern China. Some Oxytropis species have been reported to contain the mycotoxin swainsonine, an alkaloid which causes poisoning in livestock, referred to as locoism. Previous studies showed that endophytic fungi (Alternaria oxytropis) symbiotically associate with these Oxytropis species to produce swainsonine. However, the influence of variation within the Oxytropis genus on the fixation or loss of symbiosis and toxicity is poorly understood, as is the influence of environmental factors. Here we used a collection of 17 common Oxytropis species sampled in northern China to assess genetic diversity using genotyping by sequencing which was compared with the levels of the endophyte and swainsonine. Results showed that nine Oxytropis species have detectable A. oxytropis colonisation, and seven Oxytropis species contain sufficient swainsonine to be considered poisonous, whereas the rest may be non-toxic. Species variation rather than the genetic lineage was associated with the fixation or loss of endophyte and swainsonine production, which appears to have resulted from genetic drift. Genotype × Environment (G × E) effects were also found to influence endophyte and swainsonine levels amongst species of the Oxytropis genus. Our study will provide a better understanding about the evolutionary basis of A. oxytropis symbiosis and swainsonine biosynthesis in locoweeds.

Multiomics Reveals Mechanisms of Alternaria oxytropis Inhibiting Pathogenic Fungi in Oxytropis ochrocephala

“…oxytropis, the content of its metabolite swainsonine was also markedly increased (Figure ), which would further affect the health level of livestock due to the toxicity of the alkaloid. Previous studies have shown that the level of swainsonine was related to the abundance of endophytic fungi within the host population . Similarly, the hypothesis that the abundance of endophytic Alternaria was proportional to the content of swainsonine was also supported by the study of Cook et al…”

“…Previous studies have shown that the level of swainsonine was related to the abundance of endophytic fungi within the host population. 48 Similarly, the hypothesis that the abundance of endophytic Alternaria was proportional to the content of swainsonine was also supported by the study of Cook et al 9 Integrated multiomics technologies can reveal key cell signaling compounds for plant stress resistance and promote sustainable agricultural production. 49 In this study, swainsonine and apigenin-7-O-glucoside-4-O-rutinoside, metabolic biomarkers screened from pseudotargeted metabolomics, significantly inhibited the growth of pathogenic fungi Leptosphaeria sclerotioides and Colletotrichum americae-borealis by increasing the level of oxidative stress in fungi.…”

swnk plays an important role in the biosynthesis of swainsonine in Metarhizium anisopliae

“…Strain and fermentation culture M. anisopliae (Metarhizium anisopliae (Metsch.) Sorokīn), isolated in the soil, was obtained from Xi'an Jin Berry Biological Technology Co. Ltd., Shaanxi, China andinoculated onto Sabouraud medium (SDA) (Guo et al 2022) and cultured at 28°C for 10 days. Conidiums (1.0×10 7 ) of M. anisopliae were transferred into 300 mL SDA liquid culture medias (without agar) and fermented at 28°C, 180 rpm, for 1-7 d. The fermentation broth was ltered through three layers of Miracloth (EMD Millipore Corp, Billerica, MA, USA) to collect the cultures and the mycelium respectively.…”

Impaired Indole Acetic Acid and Reduced Indole-Producing Bacteria Contribute to Swainsonine-Induced Liver Inflammation

“…Swainsonine is an indolizidine alkaloid produced by the endophytic fungus Alternaria, and the chemical structure is exhibited in Figure S1. Swainsonine causes neurological disorders in livestock, and several studies have shown that swainsonine can cause liver damage before inducing neurological disorders …”