Dataset Information

Genetic Manipulation of the Ergot Alkaloid Pathway in Epichloe festucae var. lolii and Its Effect on Black Beetle Feeding Deterrence.

ABSTRACT: Epichloë endophytes are filamentous fungi (family Clavicipitaceae) that live in symbiotic associations with grasses in the sub family Poöideae. In New Zealand, E. festucae var. lolii confers significant resistance to perennial ryegrass (Lolium perenne) against insect and animal herbivory and is an essential component of pastoral agriculture, where ryegrass is a major forage species. The fungus produces in planta a range of bioactive secondary metabolites, including ergovaline, which has demonstrated bioactivity against the important pasture pest black beetle, but can also cause mammalian toxicosis. We genetically modified E. festucae var. lolii strain AR5 to eliminate key enzymatic steps in the ergovaline pathway to determine if intermediate ergot alkaloid compounds can still provide insecticidal benefits in the absence of the toxic end product ergovaline. Four genes (dmaW, easG, cloA, and lpsB) spanning the pathway were deleted and each deletion mutant was inoculated into five different plant genotypes of perennial ryegrass, which were later harvested for a full chemical analysis of the ergot alkaloid compounds produced. These associations were also used in a black beetle feeding deterrence study. Deterrence was seen with just chanoclavine present, but was cumulative as more intermediate compounds in the pathway were made available. Ergovaline was not detected in any of the deletion associations, indicating that bioactivity towards black beetle can be obtained in the absence of this mammalian toxin.

SUBMITTER: Hudson D

PROVIDER: S-EPMC7909537 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Genetic Manipulation of the Ergot Alkaloid Pathway in Epichloë festucae var. lolii and Its Effect on Black Beetle Feeding Deterrence.

Hudson Debbie D Mace Wade W Popay Alison A Jensen Joanne J McKenzie Catherine C Cameron Catherine C Johnson Richard R

Toxins 20210120 2

Epichloë endophytes are filamentous fungi (family Clavicipitaceae) that live in symbiotic associations with grasses in the sub family Poöideae. In New Zealand, E. festucae var. lolii confers significant resistance to perennial ryegrass (Lolium perenne) against insect and animal herbivory and is an essential component of pastoral agriculture, where ryegrass is a major forage species. The fungus produces in planta a range of bioactive secondary metabolites, including er ...[more]

PMID: 33498584

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Project description:Perennial ryegrass (Lolium perenne) is the most cultivated cool-season grass worldwide with crucial roles in carbon fixation, turfgrass applications, and fodder for livestock. Lolium perenne forms a mutualism with the strictly vertically transmitted fungal endophyte, Epichloë festucae var lolii. The fungus produces alkaloids that protect the grass from herbivory, as well as conferring protection from drought and nutrient stress. The rising concentration of atmospheric CO2, a proximate cause of climatic change, is known to have many direct and indirect effects on plant growth. There is keen interest in how the nature of this plant-fungal interaction will change with climate change. Lolium perenne is an obligately outcrossing species, meaning that the genetic profile of the host is constantly being reshuffled. Meanwhile, the fungus is asexual implying both a relatively constant genetic profile and the potential for incompatible grass-fungus pairings. In this study, we used a single cultivar, "Alto", of L. perenne. Each plant was infected with one of four strains of the endophyte: AR1, AR37, NEA2, and Lp19 (the "common strain"). We outcrossed the Alto mothers with pollen from a number of individuals from different ryegrass cultivars to create more genetic diversity in the hosts. We collected seed such that we had replicate maternal half-sib families. Seed from each family was randomly allocated into the two levels of the CO2 treatment, 400 and 800 ppm. Elevated CO2 resulted in an c. 18% increase in plant biomass. AR37 produced higher fungal concentrations than other strains; NEA2 produced the lowest fungal concentrations. We did not find evidence of genetic incompatibility between the host plants and the fungal strains. We conducted untargeted metabolomics and quantitative proteomics to investigate the grass-fungus interactions between and within family and treatment groups. We identified a number of changes in both the proteome and metabalome. Taken together, our data set provides new understanding into the intricacy of the interaction between endophyte and host from multiple molecular levels and suggests opportunity to promote plant robustness and survivability in rising CO2 environmental conditions through application of bioprotective epichloid strains.

Project description:Pregnant Suffolk ewes (n = 19; 81.2kg ± 7.7) estimated to be carrying twins were assigned to endophyte-infected tall fescue seed (E+; 4.14 µg ergovaline + ergovalinine/g seed) or a control diet (CON; 0 µg ergovaline + ergovalinine) and evaluated at different stages of gestation (gd85 [pre-treatment, n = 3], gd110 [n = 4/treatment] or gd133 [n = 4/treatment). Ewes were individually fed a basal diet with (E+) or without (CON) endophyte-infected tall fescue seed from gd86 to gd110 or gd133. A terminal necropsy was performed, and uterine components were evaluated for size, weight, and type. Data were analyzed using a priori contrasts to test effects of stage of gestation (gd85 vs. gd110 or gd110 vs. gd133) and adaptive responses to feeding E+ fescue seed versus CON at gd110 and gd133. Serum prolactin concentrations were greater (P < 0.05) at gd110 than gd85, and then remained constant to gd133. Feeding E+ tall fescue seed reduced (P < 0.05) serum prolactin concentrations compared to CON at both gd110 and gd133. From gd85 to gd110, placentome type and number changed from type A to type B (P < 0.05) but did not change (P > 0.05) after gd110. Total fetal weight per ewe increased 2977 g from gd85 to gd110 (P = 0.011) and then 3151 g from gd110 to 133 (P = 0.012). Brain weight as a percentage of fetal body weight was higher (P = 0.029) for E+ fetuses on gd110 compared to CON, which demonstrates asymmetrical growth and intrauterine growth restriction (IUGR). In total, 15,961 genes were identified in the cotyledon through mapping to the ovine genome across all samples. There were 136 genes differentially expressed (FDR < 0.05; log2foldchange < -1 and > 1) from gd85 to gd110 with ovarian steroidogenesis and steroid biosynthesis pathways enriched and 469 genes differentially expressed from gd110 to gd133 with ribosome and oxidative phosphorylation pathways enriched. Exposure to E+ fescue resulted in differential expression of 22 genes at gd110 but only one gene at gd133 compared to CON. These results show that there are major changes in fetal growth and placental remodeling during the late gestation period that are influenced by exposure to ergot alkaloids from endophyte-infected tall fescue seed; however, major changes in the transcriptome of the cotyledon tissue in response to E+ fescue were not observed and other factors must be involved in the reduction of placental efficiency and fetal growth observed with E+ fescue exposure.

Dataset Information

Genetic Manipulation of the Ergot Alkaloid Pathway in Epichloe festucae var. lolii and Its Effect on Black Beetle Feeding Deterrence.

Publications

Genetic Manipulation of the Ergot Alkaloid Pathway in <i>Epichloë festucae</i> var. <i>lolii</i> and Its Effect on Black Beetle Feeding Deterrence.

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