Croprotationwithnematode-resistantwheatcanprotecttomatoesInastudypublishedinCropScience,scientistsdescribeanematode-resistantwheat.Butwhilethewheatcarriestheresistancetothepest,thebenefitsareactuallyseeninthecropthatisgrownafterit.Root-knotnematodescausecroplossesaroundtheworld,andtheycanbedifficulttocontrol.Inordertoreproduce,nematodesneedtoinfectalivingplantroot.Oncetheyarepresentinsoil,theycansurvivewinterinafallowfieldandinfectplantsduringthenextgrowingseason.Trapcrops–unsuitablehoststhat“trick”thenematodesintostartingtheirlifecyclebutthenpreventthemfromreproducing–areoftenabetteroptionthanleavingthefieldfallo“Oncenematodescommittobeingaparasite,theyhavetocompletetheirlifecycle,”explainsValerieWilliamson,leadauthorofthestudyandprofessoratUniversityofCalifornia–Davis.“Iftheydon’treproduce,thepopulationdiesout.”Trapcropscanreducethenumberofparasitesinthesoilandlessentheeffectsofthepestsonthenextcropintherotation.Butcropsresistanttonematodescanbehardtofindduetothepest’swiderangeofhosts,andtrapcropsareoftenplantsthatarelessvaluabletofarmers.Inthepresentstudy,researchersfoundaresistantstrainofwheatthatcanreducenematodenumbersinsoilandprotectthenextrotationoftomatoplants.“What’sniceaboutthisfindingisthatwheatiswhatfarmersoftenuseasarotationcropinCalifornia,”saysWilliamson.Theresearchersweresurprisedtofindtheresistantwheat.Theyhadtriedanumberofdifferentrotationcropsbeforeturningtowheat.Wheatbreederandseniorco-authorJorgeDubcovskythengaveWilliamsonastrainofwheatcalledLassik.Lassikissimilartowheatthatiscommonlygrown,butithasaslightdifference.Asmallsegmentofgenesfromanotherwheatstrainrelocated,throughbreeding,intoLassik.Thisrelocatedsegmenthasnoeffectonyieldorbehaviorofthecrop,butWilliamsonandherco-authorsfoundthatitdidhaveabenefit–itmadethewheatresistanttonematodes.“Dubcovskygaveusthisstrainbecauseithadotherresistancegenesinit,”saysWilliamson.“Itturnedout,tooursurprise,thatitalsohadnematoderesistance.”OncetheyrealizedthattheLassikwheatwasmoreresistanttonematodesthanthewheatnormallygrown,theresearchteamvalidatedthesourceoftheresistancebycomparingpairsofstrainswithandwithouttherelocatedsegment.Thentodetermineifrotatingtheresistantwheatwithtomatoplantswouldhelpprotectthetomatoes,theauthorsgrewLassikwheatandusedsomeofthesoiltoplanttomatoseedlings.Thewheathadtheeffecttheywerehopingfor–thetomatoesgrowninsoilfromtheresistantwheatplotswerelessdamagedbynematodes.“Iffarmersuseawheatthatdoesnothavetheresistantgenes,morenematodessurvive,andthey’llbetherewhentheyplanttomatoes,”explainsWilliamson.“Butiftheyplanttheresistantwheat,therewon’tbeasmanynematodesinthesoil.”DubcovskynotedthatthelastthreebreadwheatvarietiesreleasedbytheUniversityofCaliforniaWheatbreedingprogramandtheUSDA-supportedTriticeae-CAPprojectallcarrythisresistancegeneandarereadilyavailabletogrowers.Theresultsfromthestudyofferapromisingoptionforreducingnematodedamage.Thenextstepistoverifythefindingsonalargerscale.Williamsonandherteamgrewplantsbothingreenhousesandinsmallmicroplots.Theyarenowanticipatingthatagronomistswilltrytherotationonafieldscale.“Wewantedtogettheresultsouttheresothatpeoplewhoworkinthefield,farmadvisersforexample,canseeifitworksinpracticeaswellasitdidinacontrolledexperiment.”译文：与抗线虫小麦轮作可以使番茄受到保护在一篇发表在《作物科学》的研究中，科学家们描述了一种抗线虫小麦。...