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Water-Deficit Stress Tolerance Differs between Two Locoweed Genera (Astragalus and Oxytropis) with Fungal Endophytes

  • Nina Klypina (a1), Matthew Pinch (a1), Brian J. Schutte (a1), Janakiraman Maruthavanan (a1) and Tracy M. Sterling (a2)...

Locoweeds are plants of the genera Astragalus and Oxytropis (Fabaceae family) and are toxic to cattle, sheep, and horses. The toxic property of locoweeds is due to the alkaloid swainsonine (SWA), which is synthesized by an endophytic fungus Alternaria spp. section Undifilum. Although the endophyte–locoweed complex is often considered mutualistic, empirical evidence for benefits to host plants is lacking. This study: 1) compared the growth, photosynthesis, and leaf pigment and antioxidant concentrations between endophyte-infected and endophyte-free plants under well-watered and water-deficit conditions; and 2) measured SWA to determine whether SWA concentrations are attenuated by water deficit and leaf age. Locoweed species in this study were woolly loco and silky crazyweed. Endophyte-infected and endophyte-free (by removal of seed coat) seedlings, as confirmed by DNA analyses, were grown under greenhouse conditions for 6 mo, after which plants were subjected to three 12- to 15-d water-deficit periods that created sublethal drought conditions. Results suggest that the endophyte did not influence photosynthetic gas exchange and leaf pigment concentrations. Under well-watered conditions only, endophyte-infected woolly loco plants had lower shoot and root biomass and higher concentrations of α-tocopherol than endophyte-free plants. SWA analyses revealed taxon-specific effects of water deficit, with water deficit increasing SWA concentrations in young leaves of woolly loco but not affecting SWA concentration in silky crazyweed. These results suggest that the endophyte behaves as a parasite in woolly loco plants grown under optimal but not under water-limited conditions. Further, results indicate that drought conditions elevate the toxicity of woolly loco plants. Improved understanding of endophyte-locoweed interactions and factors influencing SWA levels will contribute to the development of livestock management strategies to predict toxicity in particular locoweed populations.

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Associate Editor for this paper: Vijay Nandula, USDA–ARS

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DL Baucom , M Romero , R Belfon , R Creamer (2012) Two new species of Undifilum, fungal endophytes of Astragalus (locoweeds) in the United States. Botany 90:866875

K Braun , J Romero , C Liddell , R Creamer (2003) Production of swainsonine by fungal endophytes of locoweed. Mycol Res 107:980988

C Casas , JP Torretta , N Exeler , M Omacini (2016) What happens next? Legacy effects induced by grazing and grass-endophyte symbiosis on thistle plants and their floral visitors. Plant Soil 405:211229

R Chenna , H Sugawara , T Koike , R Lopez , TJ Gibson , DG Higgins , JD Thompson (2003) Multiple sequence alignment with the Clustal series of programs. Nucleic Acids Res 31:34973500

K Clay (1993) The ecology and evolution of endophytes. Agric Ecosyst Environ 44:39

D Cook , DR Gardner , DS Grum , JA Pfister , MH Ralphs , KD Welch , BT Green (2011) Swainsonine and endophyte relationships in Astragalus mollissimus and Astragalus lentiginosus . J Agric Food Chem 59:12811287

D Cook , DR Gardner , MH Ralphs , JA Pfister , KD Welch , BT Green (2009) Swainsonine concentrations and endophyte amounts of Undifilum oxytropis in different plant parts of Oxytropis sericea . J Chem Ecol 35:12721278

D Cook , DS Grum , D Gardner , KD Welch , JA Pfister (2013) Influence of endophyte genotype on swainsonine concentrations in Oxytropis sericea . Toxicon 61:105111

D Cook , L Shi , DR Gardner , JA Pfister , D Grum , KD Welch , MH Ralphs (2012) Influence of phenological stage on swainsonine and endophyte concentrations in Oxytropis sericea . J Chem Ecol 38:195203

KJ Delaney , N Klypina , J Maruthavanan , C Lange , TM Sterling (2011) Locoweed dose responses to nitrogen: positive for biomass and primary physiology, but inconsistent for an alkaloid. Amer J Bot 98:19561965

AD Elbein , R Solf , PR Dorling , K Vosbeck (1981) Swainsonine: an inhibitor of glycoprotein processing. Proc Natl Acad Sci USA 78:73937397

SH Faeth (2009) Asexual fungal symbionts alter reproductive allocation and herbivory over time in their native perennial grass hosts. Amer Nat 173:554565

DR Gardner , RJ Molyneux , MH Ralphs (2001) Analysis of swainsonine: extraction methods, detection, and measurement in populations of locoweeds (Oxytropis spp.). J Agric Food Chem 49:45734580

CE Hamilton , PE Gundel , M Helander , K Saikkonen (2012) Endophytic mediation of reactive oxygen species and antioxidant activity in plants: a review. Fungal Div 54:110

LF James , DB Nielsen , KE Panter (1992) Impact of poisonous plants on the livestock industry. J. Range Manage 45:38

S Kannadan , JA Rudgers (2008) Endophyte symbiosis benefits a rare grass under low water availability. Function Ecol 22:706713

DP Lawrence , F Rotondo , PB Gannibal (2016) Biodiversity and taxonomy of the pleomorphic genus Alternaria . Mycol Prog 15:122

YZ Li , YB Nan (2007) A new species, Embellisia astragali sp. nov., causing standing milk-vetch disease in China. Mycologia 99:406411

DP Malinkowsky , DP Belesky (2000) Adaptations of endophyte-infected cool-season grasses to environmental stresses: mechanisms of drought and mineral stress tolerance. Crop Sci 40:923940

J McLain-Romero , R Creamer , H Zepeda , J Strickland , G Bell (2004) The toxicosis of Embellisia fungi from locoweed (Oxytropis lambertii) is similar to locoweed toxicosis in rats. J Anim Sci 82:21692174

E Oldrup , J McLain-Romero , A Padilla , A Moya , D Gardner , R Creamer (2010) Localization of endophytic Undifilum fungi in locoweed seed and influence of environmental parameters on a locoweed in vitro culture system. Botany 88:512521

BM Pryor , R Creamer , RA Shoemaker , J McLain-Romero , S Hambleton (2009) Undifilum, a new genus for endophytic Embellisia oxytropis and parasitic Helminthosporium bornmuelleri on legumes. Botany 87:178194

MH Ralphs , D Cook , DR Gardner , DS Grum (2011) Transmission of the locoweed endophyte to the next generation of plants. Fungal Ecol 4:251255

MH Ralphs , R Creamer , D Baucom , DR Gardner , SL Welsh , JD Graham , C Hart , D Cook , BL Stegelmeier (2008) Relationship between the endophyte Embellisia spp. and the toxic alkaloid swainsonine in major locoweed species (Astragalus and Oxytropis). J Chem Ecol 34:3238

MH Ralphs , KE Panter , LF James (1990) Feed preferences and habituation of sheep poisoned by locoweed. J Anim Sci 68:13541362

HH Ratnayaka , WT Molin , TM Sterling (2003) Physiological and antioxidant responses of cotton and spurred anoda under interference and mild drought. J Exper Bot 54:22932305

R Rodriguez , R Redman (2005) Balancing the generation and elimination of reactive oxygen species. Proc Natl Acad Sci USA 102:31753176

RJ Rodriguez , J Henson , E Van Volkenburgh , M Hoy , L Wright , F Beckwith , YO Kim , RS Redman (2008) Stress tolerance in plants via habitat-adapted symbiosis. ISME J 2:404416

K Saikkonen , SH Faeth , M Helander , TJ Sullivan (1998) Fungal endophytes: a continuum of interactions with host plants. Annu Rev Ecol System 29:319343

K Saikkonen , P Lehtonen , M Helander , J Koricheva , SH Faeth (2006) Model systems in ecology: dissecting the endophyte-grass literature. Trends Plant Sci 11:428433

LP Singh , SS Gill , N Tutega (2011) Unraveling the role of fungal symbionts in plant abiotic stress tolerance. Plant Signal Behav 6:175191

JD Thompson , DG Higgins , TJ Gibson (2004) Clustal-W-improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position specific gap penalties and weight matrix choice. Nucleic Acids Res 22:46734680

LA Torell , LP Owen , KC McDaniel , D Graham (2000) Perceptions and economic losses from locoweed in north-eastern New Mexico. J Range Manage 53:376383

AD Vallotton , LW Murray , KJ Delaney , TM Sterling (2012) Water deficit induces swainsonine of some locoweed taxa, but with no swainsonine-growth trade-off. Acta Oecologia 43:140149

JHC Woudenberg , JZ Groenewald , M Binder , PW Crous (2013) Alternaria redefined. Stud Mycol 75:171212

BY Zhao , ZY Liu , JJ Wang , LS Sun , ZX Wang , YC Wang (2009) Isolation and NMR study on swainsonine from locoweed, Astragalus strictus . Agr Sci China 8:115120

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Weed Science
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