Association of N‐acetyl Loline and N‐formyl Loline with <i>Epichloe typhina</i> in Tall Fescue<sup>1</sup>

Bush, L. P.; Cornelius, P. L.; Buckner, R. C.; Varney, D. R.; Chapman, R. A.; Burrus, P. B.; Kennedy, Charles; Jones, Thomas A.; Saunders, Mary Jane

doi:10.2135/cropsci1982.0011183x002200050010x

Cited by 99 publications

(31 citation statements)

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“…Further modifications of 28 could yield the other natural loline alkaloids. [21][22][23] Addition of two methyl groups to the NH 2 group would yield N-methylloline. Preliminary evidence (M. J. Spiering and C. L. Schardl, unpublished results) indicates that the cytochrome P450 monooxygenase encoded by lolP [17] oxidizes one of the methyl groups of N-methylloline to a formyl group, yielding 1.…”

Section: Discussionmentioning

confidence: 99%

On the Sequence of Bond Formation in Loline Alkaloid Biosynthesis

et al. 2006

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Loline alkaloids are saturated pyrrolizidines with an oxygen bridge between carbon atoms C-2 and C-7 and an amino group on C-1. They are bioprotective alkaloids produced by Epichloë and Neotyphodium species, mutualistic fungal endophytes that are symbiotic with cool-season grasses. The sequence of bond formation in loline alkaloid biosynthesis was determined by synthesizing deuterated forms of potential intermediates and feeding them to cultures of the endophyte Neotyphodium uncinatum. These cultures incorporated deuterium from labeled N-(3-amino-3-carboxypropyl)proline and exo-1-aminopyrrolizidine into N-formylloline. The first result suggests that N-(3-amino-3-carboxypropyl)proline is the first committed intermediate in loline biosynthesis, and the second result demonstrates that the pyrrolizidine rings form before the ether bridge. The incorporation of these two compounds into lolines and the lack of incorporation of several related compounds clarify the order of bond formation in loline alkaloid biosynthesis.

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Section: Discussionmentioning

confidence: 99%

On the Sequence of Bond Formation in Loline Alkaloid Biosynthesis

et al. 2006

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“…striata (18 plants across the 3 treatments) were frozen at −20°C, freeze‐dried and ground with a Wiley mill. Plant tissue was analyzed for loline concentration as described in Bush et al (1982). Ground tissue samples were saturated and extracted in NaHCO 3 and 95:5 CH 2 Cl 2 :EtOH.…”

Section: Methodsmentioning

confidence: 99%

Stroma‐forming endophyteEpichloë glyceriaeprovides wound‐inducible herbivore resistance to its grass host

Gonthier¹,

Sullivan²,

Brown³

et al. 2008

Oikos

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Fungal endophyte-grass associations are diverse and complex. Some endophytes (e.g. Neotyphodium spp.) reproduce asexually by growing vegetatively into host seeds and many of these vertically-transmitted endophytes form mutualisms with their hosts by providing high levels of alkaloids, such as lolines, that reduce herbivore performance. Additionally, Neotyphodium coenophialum provides wound-inducible herbivore resistance through increased production of lolines. Neotyphodium likely evolved from Epichloë spp. which are sexually reproducing endophytes that are transmitted horizontally to the next host generation through production of stromata (fruiting bodies), which sterilize host grasses. We asked if wound-inducible resistance like that in N. coenophialum also occurs in the ancestral, sexually reproducing Epichloë glyceriae, which infects Glyceria striata. Host grasses were damaged by fall armyworm caterpillars, artificially cut, or left undamaged. An aphid bioassay tested the plant's toxicity to herbivores, expression of lolc (a gene in the loline biosynthesis pathway) was quantified using real-time RT-PCR, and loline concentration was quantified using gas chromatography and mass spectrometry. Artificially-damaged plants supported fewer live aphids, had greater lolc mRNA expression, and greater loline concentration than undamaged plants. Herbivore-damaged plants supported intermediate performance by aphids, low lolc mRNA expression, and minimal loline concentration. Our study is the first to demonstrate sexual endophytes can produce lolines following wounding. This suggests wound-induced responses are ancestral within the Epichloë/Neotyphodium clade and reveals a trait of grass endophytes that may have predisposed them for the evolution of defensive mutualisms with their hosts.

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“…The seeds were planted in a greenhouse and allowed to grow for 6 weeks. The leaf sheaths were then observed microscopically as in other studies (Bush et al, 1982) to verify the lack of hyphae of Neotyphodium. Bacterial strains were spray-inoculated to wetness onto eight plants for each treatment with a hand-held sprayer.…”

Section: Plant Inoculationsmentioning

confidence: 99%

Loline alkaloid production by fungal endophytes of Fescue species select for particular epiphytic bacterial microflora

Roberts

Lindow

2013

The ISME Journal

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The leaves of fescue grasses are protected from herbivores by the production of loline alkaloids by the mutualist fungal endophytes Neotyphodium sp. or Epichloë sp. Most bacteria that reside on the leaf surface of such grasses can consume these defensive chemicals. Loline-consuming bacteria are rare on the leaves of other plant species. Several bacterial species including Burkholderia ambifaria recovered from tall fescue could use N-formyl loline as a sole carbon and nitrogen source in culture and achieved population sizes that were about eightfold higher when inoculated onto plants harboring loline-producing fungal endophytes than on plants lacking such endophytes or which were colonized by fungal variants incapable of loline production. In contrast, mutants of B. ambifaria and other bacterial species incapable of loline catabolism achieved similarly low population sizes on tall fescue colonized by loline-producing Neotyphodium sp. and on plants lacking this endophytic fungus. Lolines that are released onto the surface of plants benefiting from a fungal mutualism thus appear to be a major resource that can be exploited by epiphytic bacteria, thereby driving the establishment of a characteristic bacterial community on such plants.

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Association of N‐acetyl Loline and N‐formyl Loline with Epichloe typhina in Tall Fescue¹

Cited by 99 publications

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On the Sequence of Bond Formation in Loline Alkaloid Biosynthesis

On the Sequence of Bond Formation in Loline Alkaloid Biosynthesis

Stroma‐forming endophyteEpichloë glyceriaeprovides wound‐inducible herbivore resistance to its grass host

Loline alkaloid production by fungal endophytes of Fescue species select for particular epiphytic bacterial microflora

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Association of N‐acetyl Loline and N‐formyl Loline with Epichloe typhina in Tall Fescue1

Cited by 99 publications

References 0 publications

On the Sequence of Bond Formation in Loline Alkaloid Biosynthesis

On the Sequence of Bond Formation in Loline Alkaloid Biosynthesis

Stroma‐forming endophyteEpichloë glyceriaeprovides wound‐inducible herbivore resistance to its grass host

Loline alkaloid production by fungal endophytes of Fescue species select for particular epiphytic bacterial microflora

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Association of N‐acetyl Loline and N‐formyl Loline with Epichloe typhina in Tall Fescue¹