Fungal Endophytes in Knock Out® Rose and Performance Effects of Entomopathogens on Marigold and Zinnia

in HortScience

Endophytic fungi are increasingly studied for their ability to enhance plant performance in field crops, yet there are few equivalent studies in floricultural crops. Given the economic importance of these crops and pressures faced by growers to produce plants of high aesthetic quality, we surveyed the natural occurrence of foliar fungal endophytes in Knock Out® roses to identify candidate beneficial isolates. We also tested the effects of entomopathogenic fungal inocula on marigold and zinnia plant growth using different application approaches. Our survey of Knock Out® rose foliage collected from five sites within central Texas revealed at least 24 different fungal genera and 30 probable species, including some isolates providing plant stress tolerance and pathogens or antagonists of insects and nematode pests. The effects of entomopathogen inocula on plant growth varied with host plant (marigold vs. zinnia) and inoculation method (soil drench vs. seed soak). Plant responses were complex, but inoculation with Isaria fumosorosea Wize tended to have a negative effect on plant performance characteristics whereas Beauveria bassiana (Bals.-Criv.) Vuill. tended to have positive effects. When applied to marigold as a seedcoating, I. fumosorosea reduced germination, seedling fresh weight, and produced seedlings with a less compact form. By contrast, seeds inoculated with B. bassiana required less time to germinate, had higher germination rates, and increased the plant compactness. These results show that the impact of fungal entomopathogens applied as endophytes depends on the specific fungi-plant combination being examined. The effect of plant inoculation with entomopathogenic fungi within a pest management context requires further evaluation.

Contributor Notes

This research was financially supported by the American Floral Endowment and gifts-in-kind from Ernst Benary of America, Inc. (EBA).

We are grateful to Doug Holden (EBA Global Head of Breeding) and Norbert Müller (EBA Global Head of Supply Chain) for sharing their expertise on the seed coating chemistry and for providing horticultural expertise. We also thank Cesar Valencia, lab manager for G.A. Sword, for his guidance in developing and performing the endophyte culturing techniques required for this study. A previous draft of this manuscript was improved greatly by comments provided by S.P. Arthurs and H.B. Pemberton.

ASHS member.

Corresponding author. E-mail:



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    Mean ±1 se of three plant response variables (vegetative growth, root growth, and plant weight) associated with two host plants (marigold and zinnia) and three treatments (B. bassiana or I. fumosorosea conidial preparations, or water only control) and two different inoculation methodologies (soil drench and seed soak). For each host plant and response variable, bars within each of the 6 inoculum × inoculation method clusters followed by the same letter are not significantly different at P = 0.05.

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    Mean fresh weight (g) of 3-week old T. erecta plants grown from uncoated and methylisothiazolinone-coated seeds inoculated with B. bassiana, sterile control, and I. fumosorosea. Shared letters indicate no significant difference between the treatments (Tukey’s honestly significant difference, P > 0.05). Error bars represent 1 standard error.

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    Mean height:width ratio of 3-week old T. erecta plants grown from uncoated and methylisothiazolinone-coated seeds inoculated with B. bassiana or I. fumosorosea vs. sterile control. Columns with shared letters indicate no significant difference between the treatments (Tukey’s honestly significant difference, P > 0.05). Error bars represent 1 standard error.


AfzalI.RehmanH.U.NaveedM.BasraS.M.A.2016Recent advances in seed enhancements p. 47–74. In: A. Susana and B. Alma (eds.). New Challenges in Seed Biology-Basic and Translational Research Driving Seed Technology. InTechOpen Limited London UK

AliS.WuJ.HuangZ.RenS.X.2010Production and regulation of extracellular chitinase from the entomopathogenic fungus Isaria fumosoroseaBiocontrol Sci. Technol.207723738

AndersenB.NielsenK.F.PintoV.F.PatriarcaA.2015Characterization of Alternaria strains from Argentiniean blueberry, tomato, walnut and wheatIntl. J. Food Microbiol.196110

Anonymous2018Tagetes erecta Discovery Yellow African Marigold Culture Guide. <>

ArnoldA.E.LutzoniF.2007Diversity and host range of foliar fungal endophytes: Are tropical leaves biodiversity hotspots?Ecology883541549

AsrarA.W.A.ElhindiK.M.2011Alleviation of drought stress of marigold (Tagetes erecta) plants by using arbuscular mycorrhizal fungiSaudi J. Biol. Sci.189398

BabuB.DankersH.NewberryE.2014First report of rose rosette virus associated with rose rosette disease infecting knockout roses in FloridaPlant Dis.98101449

Ball Seed2019Seed Product Information Guide. Ball Horticultural Company. Chicago IL

BarnettH.L.HunterB.B.1998Illustrated genera of imperfect fungi No. 4. Amer. Phytopathological Soc. (APS Press) St. Paul MN

BiermannB.J.LindermanR.G.1983Increased geranium growth using pretransplant inoculation with a mycorrhizal fungusJ. Amer. Soc. Hort. Sci.108972976

CarrollG.C.1988Fungal endophytes in stems and leaves: From latent pathogen to mutualistic symbiontEcology6929

CollaG.RouphaelY.BoniniP.CardarelliM.2015Coating seeds with endophytic fungi enhances growth, nutrient uptake, yield and grain quality of winter wheatIJPP92171189

D’AmicoM.FrisulloS.CirulliM.2008Endophytic fungi occurring in fennel, lettuce, chicory, and celery—commercial crops in southern ItalyMycol. Res.1121100107

DaraS.K.DaraS.R.DaraS.S.2013Endophytic colonization and pest management potential of Beauveria bassiana in strawberriesJ. Berry Res.34203211

DaraS.K.DaraS.R.DaraS.S.2017Impact of entomopathogenic fungi on the growth, development, and health of cabbage growing under water stressAmer. J. Plant Sci.812241233

De CalA.LarenaI.LiñánM.TorresR.LamarcaN.UsallJ.DomenichiniP.BelliniA.De EribeX.O.MelgarejoP.2009Population dynamics of Epicoccum nigrum, a biocontrol agent against brown rot in stone fruitJ. Appl. Microbiol.106592605

EkesiS.ManianiaN.K.Ampong-NyarkoK.1999Effect of temperature on germination, radial growth and virulence of Metarhizium anisopliae and Beauveria bassiana on Megalurothrips sjostedtiBiocontrol Sci. Technol.9177185

Ek-RamosM.J.ZhouW.ValenciaC.U.AntwiJ.B.KalnsL.L.MorganG.D.KernsD.L.SwordG.A.2013Spatial and temporal variation in fungal endophyte communities isolated from cultivated cotton (Gossypium hirsutum)PLoS One86E66049

ElenaG.BeatrizP.J.AlejandroP.LecuonaR.E.2011Metarhizium anisopliae (Metschnikoff) Sorokin promotes growth and has endophytic activity in tomato plantsAdv. Biol. Res. (Faisalabad)52227

FávaroL.C.SebastianesF.L.AraújoW.L.2012Epicoccum nigrum P16, a sugarcane endophyte, produces antifungal compounds and induces root growthPLoS One76E36826 doi: 10.1371/journal.pone.0036826.

GangeA.C.EschenR.WearnJ.A.ThawerA.SuttonB.C.2012Differential effects of foliar endophytic fungi on insect herbivores attacking a herbaceous plantOecologia168410231031

GanleyR.J.BrunsfeldS.J.NewcombeG.2004A community of unknown, endophytic fungi in western white pineProc. Natl. Acad. Sci. USA1011010710112

GaurA.AdholeyaA.2005Diverse response of five ornamental plant species to mixed indigenous and single isolate arbuscular-mycorrhizal inocula in marginal soil amended with organic matterJ. Plant Nutr.28707723

GurulingappaP.SwordG.A.MurdochG.McGeeP.2010Colonization of crop plants by fungal entomopathogens and their effects on two insect pests when in plantaBiol. Control5513441

HarpD.A.ZlesakD.C.HammondG.GeorgeS.MackayW.2009Earth-Kind® Rose Trials–identifying the world’s strongest, most beautiful landscape rosesFloric. Ornam. Biotechnol.3166175

HarringtonG.T.1921Temperatures for flower seed germinationBot. Gaz.726337358

HouX.Q.GuoS.X.2009Interaction between a dark septate endophytic isolate from Dendrobium sp. and roots of D-nobile seedlingsJ. Integr. Plant Biol.51374381

HoyM.A.SinghR.RogersM.E.2010Evaluations of a novel isolate of Isaria fumosorosea for control of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae)Fla. Entomol.9312432

HuangW.-Y.CaiY.Z.HydeK.D.CorkeH.SunM.2007Endophytic fungi from Nerium oleander L (Apocynaceae): Main constituents and antioxidant activityWorld J. Microbiol. Biotechnol.23912531263

HumberR.A.1997Chapter V-1: Fungi: Identification p. 153–185. In: L. Lacey (ed.). Manual of Techniques in Insect Pathology. Academic Press San Diego CA.

Incotec2017Disco™ Classic Yellow L-072 Product Information Sheet.

JaberL.R.EnkerliJ.2017Fungal entomopathogens as endophytes: Can they promote plant growth?Biocontrol Sci. Technol.2712841

JacksonM.A.DunlapC.A.JaronskiS.T.2010Ecological consideration in producing and formulating fungal entomopathogens for use in insect biocontrolBioControl5511291145

JungesE.Brião MunizM.F.BastosB.D.O.OruoskiP.2016Biopriming in bean seeds. Acta Agric. ScandB Soil Plant Sci.663207214

KhanA.L.ShinwariZ.K.KimY.H.WaqasM.HamayunM.KamranM.LeeI.J.2012Role of endophyte Chaetomium globosum LK4 in growth of Capsicum annuum by production of gibberellins and indole acetic acidPak. J. Bot.4416011607

LopezD.C.SwordG.A.2015The endophytic fungal entomopathogens Beauveria bassiana and Purpureocillium lilacinum enhance the growth of cultivated cotton (Gossypium hirsutum) and negatively affect survival of the cotton bollworm (Helicoverpa zea)Biol. Control895360

LopezD.C.Zhu-SalzmanK.Ek-RamosM.J.SwordG.A.2014The entomopathogenic fungal endophytes Purpureocillium lilacinum (formerly Paecilomyces lilacinus) and Beauveria bassiana negatively affect cotton aphid reproduction under both greenhouse and field conditionsPLoS One98e103891

LouJ.FuL.PengY.ZhouL.2013Metabolites from Alternaria fungi and their bioactivitiesMolecules1858915935

MagnitskiyS.2004Controlling seedling height by treating seeds with plant growth regulators. (Electronic Thesis or Dissertation). <>

MárquezS.S.BillsG.F.HerroN.ZabalgogeazcoaI.2012Non-systemic fungal endophytes of grassesFungal Ecol.53289297

MartinC.M.2010Comparison of organic and inorganic fertilizers on the growth and development of containerized Rosa hybrid ‘Radtko’ and Hibiscus rosa-sinensis ‘Evangeline.’ M.S. Thesis. Stephen F. Austin State University Nacogdoches TX. ProQuest. <>

MartinR.C.DombrowskiJ.E.2015Isolation and identification of fungal endophytes from grasses along the Oregon CoastAmer. J. Plant Sci.61932163230

MayerhoferM.S.KernaghanG.HarperK.A.2013The effects of fungal root endophytes on plant growth: A meta-analysisMycorrhiza232119128

PosadaF.VegaF.E.2006Inoculation and colonization of coffee seedlings (Coffea arabica L.) with the fungal entomopathogen Beauveria bassiana (Ascomycota: Hypocreales)Mycoscience47284289

RobertsR.H.StruckmeyerB.E.1939Further studies of the effects of temperature and other environmental factors upon the photoperiodic responses of plantsJ. Agric. Res.599699709

SaikkonenK.FaethS.H.HelanderM.SullivanT.J.1998Fungal endophytes: A continuum of interactions with host plantsAnnu. Rev. Ecol. Syst.29319343

SAS Institute Inc2016JMP® 13 Automation Reference. SAS Institute Inc. Cary NC

SigmaPlot Version 11.22008Systat Software Inc. San Jose CA

StoneJ.K.BaconC.W.WhiteJ.F.2000An overview of endophytic microbes: Endophytism defined p. 3–29. In: C.W. Bacon and J.F. White Jr. (eds.). Microbial endophytes. Marcel Dekker Inc. New York NY Luna Alves LimaE.A.Figueiredo PortoA.L.2013Horizontal transmission and effect of the temperature in pathogenicity of Beauveria bassiana against Diatraea saccharalis (Lepidoptera: Crambidae)Braz. Arch. Biol. Technol.563413419

ThommaB.P.H.J.2003Alternaria spp.: From general saprophyte to specific parasiteMol. Plant Pathol.4225236

U.S. Department of Agriculture2014National Agricultural Statistics Service. 2014 Census of Horticultural Specialties

U.S. Department of Agriculture2016National Agricultural Statistics Service. Floriculture Crops 2015 Summary

VegaF.E.2008Insect pathology and fungal endophytesJ. Invertebr. Pathol.98277279

VegaF.E.GoettelM.S.BlackwellM.ChandlerD.JacksonM.A.KellerS.KoikeM.ManianiaN.K.MonzonA.OwnleyB.H.PellJ.K.RangelD.E.N.RoyH.E.2009Fungal entomopathogens: New insights on their ecologyFungal Ecol.2149159

WilsonD.2000Endophyte – the evolution of a term, and clarification of its use and definitionOikos732274276

YanX.N.SikoraR.A.ZhengJ.W.2011Potential use of cucumber (Cucumis sativus L.) endophytic fungi as seed treatment agents against root-knot nematode Meloidogyne incognitaJ. Zhejiang Univ. Sci. B123219225

YeoH.PellJ.K.AldersonP.G.ClarkS.J.PyeB.J.2003Laboratory evaluation of temperature effects on the germination and growth of entomopathogenic fungi and on their pathogenicity to two aphid speciesPest Mgt. Sci.59156165

ZhouZ.ZhangC.ZhouW.LiW.ChuL.YanJ.LiH.2014Diversity and plant growth-promoting ability of endophytic fungi from the five flower plant species collected from Yunnan, Southwest ChinaJ. Plant Interact.91585591

ZhouW.StarrJ.L.KrummJ.L.SwordG.A.2016The fungal endophyte Chaetomium globosum negatively affects both above- and belowground herbivores in cotton. FEMS Microbiol. Ecol. 92(10) doi:

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