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Evaluation of Aegilops Species for Resistance to Wheat Powdery

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Evaluation of Aegilops Species for Resistance to Wheat Powdery Evaluation of Aegilops Speciesfor Resistanceto Wheat Powdery Mildew, Wheat Leaf Rust, HessianFly, and Greenbug B. S. GILL, H. C. SHARMA, and W. J. RAUPP, Department of Plant Pathology, L. E. BROWDER, J. H. HATCHETT, USDA-ARS, and T. L. HARVEY, Fort Hays Branch, Kansas State University, Manhattan 66506; J. G. MOSEMAN, Plant Geneticsand GermplasmInstitute, USDz\-z\RS, Beltsville,MD 20705;andJ. G. Wz\INES, Department of Botany and Plant Sciences,University of California, Riverside 92521 composites possessed most of the ABSTRACT virulence genes found in the United Gill,B S,Sharma,H C,Raupp,W J,Browder,L E,Hatchett,J H.,Harvey,T L,Moseman, States.After inoculation,seedlings were J. G, and Waines,J. G. 1985 Evaluation of Aegilops speciesfor resistanceto wheat powdery maintainedat 16-19 C with light for 12 mildew, wheat leaf rust, Hessianfly, and greenbug. Plant Disease69: 314-316 hr/day. Reactionsto infectionwere read Thirty-seven to 187accessions of l6-21 Aegilops specieswere evaluatedfor resistanceto powdery 7-9 days after inoculation on a scaleof mrldew (Erysiphe graminis tritici),leaf r:usl(Puccinia recondita trlllcl), Hessian f7y (Mayetiola 0-9, where0: immune,no visiblesigns of destructor), and greenbug (Schizaphisgraminum). A high frequency of resistanceto powdery infection; l-3: highly resistant, mildew, leaf rust, and Hessianfly occurredamong the ,4egilops speciesThe frequencyof resistance increasing from no necrosis to large to greenbugwas low and limited mainly to speciescontaining the S-, D-, and C-geno mes. M ultiple necrotic areas. increasing from no resrstanceto two pathogensand two insectswas identified in one accessioneach of A. caudata,A. mycelium to little mycelium; 4-6 : longissima, A. speltoides,and A. variabills, and to two pathogensand Hessianfly in six Aegilops intermediatelyresistant, necrotic areas specres. changingto chloroticareas. increasing in amounts of mycelium and conidiospore production; and 7-9 : susceptible, Pathogens and insects cause crop graphic regions, Aegilops specles were decreasingfrom chlorotic areas to no losses and instability in wheat yield. expectedto be rich sourcesof genetic chlorosis, increasing in amount of Breedingresistant cultivars is perhapsthe variation. Resistanceto different patho- mycelium and conidiosporeproduction most economical method of control. gens has been identified in Aegilops to completesusceptibility (l I,l6). Genes for resistance are frequently species(1,12), and a recent literature Seedlingswere testedfor reactionsto overcomeby new racesof pathogensand review (15) cited severalwheat cultivars Pucciniarecondita Rob. ex Desm.f. sp. insects,however, and differentsources of with resistancegenes from Aegilops tritici cultrtre PRTUS6 using the resistanceare needed to competewith the The complete range of genetic urediniospore-oilsuspension inoculation continuously evolving virulence of pest variation that occurs in different method and plant growing method populations.Moreover, because breeding Aegilops speciesis not known. Pasquini described by Browder (2) Culture a crop impoverishesits geneticbase, it is ( I 2) evaluated the Aegilops speciesin the PRTUS6 was selectedbecause it was imperative that exotic gene pools be USDA world collection of small grains virulentto lineswith severalof the known identifiedand incorporatedinto breeding for resistanceto leaf rust, stem rust, and Lr genesand many commercial cultivars programs. powdery mildew Our study was under- grown in Kansas. PRTUS6 can be The genus,4egilopsis a usefulsource of taken to evaluate previously untested describedwith the avirulence/virulence alien genetic variation for disease accessions of Aegilops species in the formula 2a,9, 16, 18,19, 24 1,2c, 2d, 3a, resistancein wheat Thereare 1l diploid, University of California-Riverside 1 10, I I, 17.Infection types were produced 9 tetraploid, and 4 hexaploid speciesof (UCR) collection(excluding,4. squarrosa) undergrowth chamberconditions at 20+ Aegilop s distributed in southwestern for resistanceto powdery mildew, leaf 2 C and a l2-hr day at about 2,000 lux. Asia including Caucasus,northern Africa, rust, Hessianfly, and greenbug. Infectiontypes were observed l0-l 2 days and southern Europe (17). Becauseof after inoculationand codedaccording to their wide adaptationto diverseecogeo- MATERIALS AND METHODS the systemof Browder and Young (3). A More than 300 accessionsof Aegilops line wasconsidered resistant if associated Cooperative investigations of Kansas Agricultural species are represented in the UCR with an infectiontype with a sporulation Experiment Station, California Agricultural collection.These accessions were increased rating of 0, I, or 2 on a scaleof 0-9. Experiment Station,and USDA-ARS; Contribution 85-8-J, Department of Plant Pathology, Kansas at KansasState University.Fifteen to 20 Accessions were evaluated in a Agricultural Experiment Station, Kansas State seeds were used in evaluating each greenhousefor resistanceto biotypeD of University, Manhattan Researchsupported in part accessionfor reactionsto eachpathogen Hessian fly (Mayetiola destructor Say). by grants from Kansas Wheat Commission, Kansas and insect. Biotype D larvae infest wheats carrying Crop Improvement Association, and Pioneer Hi- Bred Co The accessionswere evaluated for Hl, H2, H3, h4, H6, H7, and I18 genes powdery mildew caused by Erysiphe but not wheats carrying H5 or H9. Present address of second author: Monsanto graminis DC. ex Merat f. sp. tritici em Greenhousetemperature was maintained Agricultural Products Co , 700 Chesterfield Village Marchal by inoculating seedlings in at about 20 C throughoutthe test Twenty Parkway, Chesterfield,MO 63067 separateplantings with one compositeof seedsof eachaccession were seeded in a Accepted for publication 26 September 1984 cultures ABK and l2'7 and another of row in standard greenhouse flats culturesMo 10and Quincyin greenhouse containing soil (10 rows per flat). The publicationcosts of this artrclewere defraved in oart tests. The virulent/avirulent formulas Methods of infestationand of determining by pagecharge payment This articlemust therefore be ( : hereby marked"advettisement" in accordancewith 18 I I ) of the culturesare as follows: A BK resistanceor susceptibilityof individual U S C S1734 solely to indicatethis fact 1,2, 6,1 13a,3b,3c, 4,5, 8, Ma, Amigo; seedlingswere similar to thosedescribed 127: 3b,3c,51 1,2,3a,4,6, 7, 8, Ma, by Cartwright and LaHue (4). Adult public This article is in the domain and not copy- Amigo; Mo l0 = 2, 3a, 3c, 5, 7, Ma, Hessianflies were allowed to oviposit on rightable lt may be freely reprinted with cus- :2,3a, tomary crediting of the source The American Amigo/ 1,3b, 4, 6, 8; and Quincy seedlingsin the oneJeafstage for 2 days. Phytopathological Society, 1985 3c,4, Ma I I , 3b, 5, 6, 7, 8, Amigo. The two Plantswere then examinedfor eggsand 314 PlantDisease/Vol. 69 No. 4 infested with l0-15 eggsper plant. Plant accessioneachof A. caudata(Manhattan accessions, from A. umbellulata, A. reaction was determined about l5 days accession1905), A. longissima(1924), A. triaristata, A. triuncialis, A. comosa, and after infestation; individual plants were speltoides(17 83), and ,4. variabilis (1889) A. ovata, were resistant to powdery classified as resistant or susceptible. wasresistant or segregatingfor resistance mildew, leaf rust, and Hessian fly but Suscepiibleplants were stunted and dark to all four pathogens and insects. One were susceptibleto greenbug. green.Resistant plants werenot stunted; accessioneach of A. sharonensrs(2065) they were yellowish green and showed a and A. variabilis (1898) was susceptible DISCUSSION high level of antibiosis in that all larvae only to leaf rust. The remaining This survey shows that Aegilops died in the first instar. Resistant and susceptibleplants werealso examinedfor dead or live larvae;live larvae werefound Tabfe l. Evaluation ofaccessionsofdiploid speciesof Aegilops for resistanceto powdery mildew only on susceptibleplants. leaf rust. Hessianfly. and greenbug" Greenbug (Schizaphis graminum Powdery mildew Leaf rust Hessian fly Greenbug Rond.) biotype E, the predominant biotype in the Midwest, attacks both Speciesand genome RSR R wheat and sorghum. Amigo wheat, which A. speltoides (S)o 1"0 t6 I l2 (6H) tl t2 was resistant to biotype C, is susceptible A. longissima (SP) 20 22 3 (2H) 3 l(H) l to biotype E. For the greenbugresistance A. sharonensis(S"n) 20 l(H) 3 | (H) I 2 (rH) 0 test, l0 apterous adult biotype E A. bicornis (Sb) 4 (2r) 0 l8 2 (H) 3 UI (C) (H) I greenbugswere placed on each plant at A. caudata ll ll I l0 A. umbellulara (U) 6 (3r) 0 l0 (lH) l 5 (H) I r(r) 6 the two- to threeJeaf stage,and the plants A. comosa(M) 2.(rr) )L 2 were enclosed in plastic cages in a A. uniaristata (Un) .1. 02 '!:) greenhouse maintained at about 22 C. A. mutica (Mt) 0l 0 I : Resistancewas determined 8-10 days A. searsii(S) tl later. Susceptible plants began to show Total accessions t8 2 36 22 25 23 619 generalizedchlorosis after 5-7 days and "R=resistant,I:intermediateresistant,S:susceptible,andH=segregatingRandS. ospecies were easily distinguished from the dark genomesymbols from Kimber (10) green resistant plants. Resistance 'Number of accessionswith indicated diseasereactron. involves toleranceas well as antibiosis and/ or nonpreference(8). Table 2. Evaluation of accessionsof polyploid speciesof Aegilops for resistanceto powdery mildew, leaf rust, Hessianfly, and greenbug' RESULTS A variable number of accessions, Powdery mildew Leaf rust Hessian fly Greenbug depending on
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