Ergopeptines bromocriptine and ergovaline and the dopamine type-2 receptor inhibitor domperidone inhibit bovine equilibrative nucleoside transporter 1-like activity

Molecular mechanisms in grass-Epichloë interactions: towards endophyte driven farming to improve plant fitness and immunity

All plants harbor many microbial species including bacteria and fungi in their tissues. The interactions between the plant and these microbes could be symbiotic, mutualistic, parasitic or commensalistic. Mutualistic microorganisms are endophytic in nature and are known to play a role in plant growth, development and fitness. Endophytes display complex diversity depending upon the agro-climatic conditions and this diversity could be exploited for crop improvement and sustainable agriculture. Plant-endophyte partnerships are highly specific, several genetic and molecular cascades play a key role in colonization of endophytes in host plants leading to rapid changes in host and endophyte metabolism. This results in the accumulation of secondary metabolites, which play an important role in plant defense against biotic and abiotic stress conditions. Alkaloids are one of the important class of metabolites produced by Epichloë genus and other related classes of endophytes and confer protection against insect and mammalian herbivory. In this context, this review discusses the evolutionary aspects of the Epichloë genus along with key molecular mechanisms determining the lifestyle of Epichloë endophytes in host system. Novel hypothesis is proposed to outline the initial cellular signaling events during colonization of Epichloë in cool season grasses. Complex clustering of alkaloid biosynthetic genes and molecular mechanisms involved in the production of alkaloids have been elaborated in detail. The natural defense and advantages of the endophyte derived metabolites have also been extensively discussed. Finally, this review highlights the importance of endophyte-arbitrated plant immunity to develop novel approaches for eco-friendly agriculture.

Do Epichloë Endophytes and Their Grass Symbiosis Only Produce Toxic Alkaloids to Insects and Livestock?

Epichloë endophytes in forage grasses have attracted widespread attention and interest of chemistry researchers as a result of the various unique chemical structures and interesting biological activities of their secondary metabolites. This review describes the diversity of unique chemical structures of taxa from Epichloë endophytes and grass infected with Epichloë endophytes and demonstrates their reported biological activities. Until now, nearly 160 secondary metabolites (alkaloids, peptides, indole derivatives, pyrimidines, sesquiterpenoids, flavonoids, phenol and phenolic acid derivatives, aliphatic metabolites, sterols, amines and amides, and others) have been reported from Epichloë endophytes and grass infected with Epichloë endophytes. Among these, non-alkaloids account for half of the population of total metabolites, indicating that they also play an important role in Epichloë endophytes and grass infected with Epichloë endophytes. Also, a diverse array of secondary metabolites isolated from Epichloë endophytes and symbionts is a rich source for developing new pesticides and drugs. Bioassays disclose that, in addition to toxic alkaloids, the other metabolites isolated from Epichloë endophytes and symbionts have notable biological activities, such as antifungal, anti-insect, and phytotoxic activities. Accordingly, the biological functions of non-alkaloids should not be neglected in the future investigation of Epichloë endophytes and symbionts.

Activities and Effects of Ergot Alkaloids on Livestock Physiology and Production

Consumption of feedstuffs contaminated with ergot alkaloids has a broad impact on many different physiological mechanisms that alters the homeostasis of livestock. This change in homeostasis causes an increased sensitivity in livestock to perturbations in the ambient environment, resulting in an increased sensitivity to such stressors. This ultimately results in large financial losses in the form of production losses to livestock producers around the world. This review will focus on the underlying physiological mechanisms that are affected by ergot alkaloids that lead to decreases in livestock production.

NutriPhysioGenomics applications to identify adaptations of cattle to consumption of ergot alkaloids and inorganic versus organic forms of selenium: altered nutritional, physiological and health states?

NutriPhysioGenomics (NPG) seeks to measure nutrition-responsive genome expression during specific physiological states, thus defining how a given challenge alters the ‘basal’ transcriptome. Application of NGS regimens (transcriptome and bioinformatics analyses) in combination with targeted-gene approaches has revealed cellular mechanisms putatively responsible for complex, whole-animal, metabolic syndromes such as heat stress and subacute ruminal acidosis. Using similar approaches, our laboratory sought to understand how the basal physiology of developing cattle adapted to two prevalent health challenges of forage-based beef cattle production in south-eastern USA: fescue toxicosis and selenium (Se) deficiency. In Model 1, pituitary and hepatic genomic expression profiles of growing beef steers grazing high (E+, n = 9) versus low (E–, n = 10) endophyte-infected tall fescue pastures for 85 days, and consuming sodium selenite (ISe) as a free-choice Se supplement, were compared by a combination of microarray, bioinformatic, and targeted-gene/protein (real-time reverse transcription–PCR, Nanostring, immunoblot) analyses. In Model 2, hepatic genomic expression profiles of growing beef heifers (0.5 kg gain/day) fed a cotton seed hull-based diet and different sources (n = 9) of dietary Se (3 mg/day) supplements (no supplement, Control; inorganic Se, sodium selenite, ISe; organic Se, Sel-Plex; OSe), or a 1.5 mg : 1.5 mg blend of ISe and OSe, MIX) were compared after 168 days of supplementation, as described for Model 1. The results for Model 1 showed, that in the pituitary of E+ steers, expression of genes for prolactin signalling; redox capacity; regulation of lactotroph, gonadotroph, and thyrotroph proliferation; gonadotropin-releasing hormone-mediated signalling; and Se-based metabolism was impaired. Concomitantly, the livers of E+ steers had an increased level of expression of genes encoding proteins responsible for shunting of amino acid carbons into pyruvate and ATP synthesis capacity (oxidative phosphorylation pathway, mitochondrial mass), increased serine and proline biosynthesis, and reduced selenoprotein-mediated metabolism. Result for Model 2 showed that, overall, there were clear differences in the profiles of differentially expressed genes (DEG) among the four Se treatment groups, with the form of Se administered being more reflective of DEG profiles than the total amount of Se assimilated. Moreover, hepatic transcriptomes profiles of MIX heifers revealed an increased potential for selenoprotein synthesis and selenoprotein-mediated metabolism. In addition, several genes involved with increased redox capacity were upregulated in MIX versus ISe heifers. Taken together, our NGS approach characterised adaptation to physiological challenges and, serendipitously, identified suppression of several metabolic pathways by consumption of ergot alkaloid consumption that have the potential to be increased with supplementation of the MIX form of Se.