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5. Whydoestheorganicsectornotwant‘PPFhybridvarieties’? Noinbredplantswantedinhybridseed Section3explainsthattheadvantageofhybridvarietiesistheiruniformity.However,beforeplantsofa hybridvarietyareactually100%uniform,thereisanotherproblemtobetackled.Themotherlineshould notbeallowedtoself-pollinate,asotherwisetheseedlotwillcontaindeviatinginbredplants.Thereare variouswaysofpreventingthis,dependingonthecrop. Manualemasculationandmanualpollination Manualremovalofstamens(‘emasculation’)andpollinationisrelativelyexpensive.Inthecaseofcrops suchastomatoes,peppers,cucumbers,courgettesandpumpkinsthisisworthitandiscarriedout(see Figures1and2).Oftenthestamensarefirstofallremovedfromthemotherlinetoensurethatselfpollinationcannottakeplace. Figure1.Manualremovalofstamensfromatomatoflower(Photo:J.Myers,OSU) Figure2.Manualpollinationoftomatoflowers(Photo:F.Meijer-Dekens,WUR) 11 Usingnaturalmalesterility Inthecaseofmostfieldcropsmanualpollinationisnoteconomicallyfeasible.Itmakestheseedtoo expensive.Theonlyalternativeistolookforgeneticmechanismsasaresultofwhichthemotherline doesnotself-pollinate.Inthecaseofcropssuchascarrots,onionsandleeksmalesterility(MS) sometimesoccursnaturally.Thesemale-sterileplantscanberecognisedbythefactthattheirflowersdo nothavestamens.Theseplantscanbeusedinbreedingasthemotherlineinordertoavoidthemother linebeingabletoself-pollinate.Thismalesterilityoccursnaturallyinthenucleusofsometypesofcrops butnotinallcrops.Inthecaseofsomecrops(sunflowersandradishes)malesterilityistobefoundnotin thenucleusbutnaturallyinthecytoplasmaofthecell;inthiscaseitiscalledcytoplasmicmalesterility, abbreviatedtoCMS. Table1.Overviewofseveralcropswithandwithoutnaturalmalesterilityinthenucleus(MS)andcytoplasmic malesterility(CMS)andpossiblealternatives. Crops Cucumber NaturalMS No NaturalCMS No Cabbage No No Carrots Radishes Tomatoesand peppers Onions Chicory Yes Unknown Notnecessary No Yes No Yes No No No Sunflowers Probablynot Yes Alternatives Cucumbersproduceseparatefemaleandmaleflowersontheplant. ThereareF1hybridsonthemarketthatproduceonlyfemaleflowers. Tobeabletoobtainpollenforseedcultivationthefatherlinedoes havetoproducemaleflowers(usingplanthormones). ‘Self-incompatibility’,i.e.theplantdoesnotacceptitsownpollenbut prefersthatofanotherplant.Thischaracteristicisoftennot100% effectiveandsometimesundercertainconditionsproducesupto around10%inbredplants.However,thisdoesinpracticeworkfairly well. Notnecessary. Notnecessary. Manualemasculationcanbedonewell(i.e.removingthestamenswith tweezers). Notnecessary. Chicoryalsohasaformof‘self-incompatibility’.Inthe‘normal’hybrid processinthecaseofchicoryalimitednumberofgenerationsare inbredandseveralinbredplantswillalwaysbeproduced. Notnecessary. Naturalself-incompatibility Inthecaseofseveralcrops(cabbageandchicory)malesterilitydoesnotoccuratall.Inthecaseofthese cropsthereisanothermechanismavailable:so-calledself-incompatibility.Thismechanismensuresthata plant(inmostcases)doesnotacceptitsownpollen.Itisacomplexcharacteristicandnotallbreeding companieshaveagoodsetofgenesthatensureself-incompatibility. ArtificialCMSincabbageandchicoryviaprotoplastfusion:PPFhybrids Breederswantcompletemalesterilityandtrytointroducethischaracteristicfromanother(non-crossable buttosomeextentrelated)typeofplantartificially.CMSwasintroducedtocabbagefromradishesvia protoplastfusion(i.e.unnaturally);inthecaseofchicorythiswasdoneusingsunflowers.Inthecaseof boththesecropscompletesterilityisachievedonlyusingforcedprotoplastfusion,seeFigure6.Tothis endfirstofallthecellwallisdissolvedusinganenzymetreatment,sothattheprotoplasts(thecells withoutacellwall)canbefusedusingelectricalstimuliandtheorganellesandthemitochondriaare combined,asaresultofwhichCMSistransferredtotheotherdesiredspecies. 12 Figure6.Processofprotoplastfusion betweentwodifferentplants.Source: FiBldossier2001 Protoplastfusion(PPF)isnotadesirabletechniquefortheorganicsector ThereasonthatPPFtechniquesareformallypermittedwithinorganicfarmingiscomplicated.Itistodo withinternationaldefinitions,legislationandreferences.Forseveralcountriesthisacceptanceisareason todrawupadditional‘private’rulesfortheuseof‘PPFhybrid’varietiesthatwereobtainedusingthese techniques.Severalmarketplayers,suchasDemeter,BiolandandNaturland,haveforbiddentheusein Germanyofvarietiesproducedusingprotoplastfusion. In2013therewasanuproarintheGermanmediaabout'geneticallymodifiedorganicchicory'.Thiswas aboutorganicchicorythathadbeencultivatedusingseedfromaso-calledPPFvariety(conventionally producedseed). HowcangrowersknowthattheyarenotgettingaPPFhybridofcabbageandchicory? Noteveryseedcompanyindicateswhichhybridvarietiesweredevelopedonthebasisofprotoplast fusion.Seedcompaniesintheorganicsectorconsciouslytakeintoaccounttheobjectionstoprotoplast fusionandputonlyorganicseedofF1hybridvarietiesonthemarketdevelopedonthebasisofselfincompatibility(so-calledSIvarieties).ThisdoesnotalterthefactthatthereareonlyafewsuitableSI chicoryvarietiesonthemarketandtherearenoseedcompaniesthatinvestinthedevelopmentofnewSI chicoryvarieties.InthecaseofcabbagethereareSIvarietiesbeingmaintained,inparticularbyBejo, Enza/VitalisandRijkZwaan.Butitisclearthatthereneedstobeinvestmentinthebreedingofnew organicvarieties. 13