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耳草属二型花柱植物隐性与异型自交不亲和机制的比较研究.docx

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耳草属二型花柱植物隐性与异型自交不亲和机制的比较研究 Introduction Eargrassisagenusofplantsthatisknownforitsuniquecharacteristicsofhavingtwodifferenttypesofpistils,namely,thelongandshortpistil.Studieshaveshownthateargrassexhibitsbothcrypticandheteromorphicself-incompatibilitymechanismsthatpreventself-fertilizationbypollenfromthesameplant.Thisstudyaimstocompareandcontrastthecrypticandheteromorphicself-incompatibilitymechanismsofeargrassinrelationtoplantbreedingandgeneticdiversity. Crypticself-incompatibility Crypticself-incompatibilityisamechanismthatoccursinplantswherebyself-pollenisnotrecognizedas“self”.Itinvolvesaseriesofbiochemicalprocessesthatresultintherejectionofself-pollen.Eargrassexhibitscrypticself-incompatibilityduetoasingleallelethatpreventspollengrowthandfertilizationinthepresenceofthesameallele.Thecrypticmechanismservestomaximizegeneticdiversityineargrasspopulationsbyrestrictingself-pollination. Heteromorphicself-incompatibility Heteromorphicself-incompatibilityisamechanismthatoccursinplantsthathavedifferenttypesofflowerswithdifferentpistilstypes.Eargrasshasbothlongandshortpistils,andthesedifferenttypesofpistilsservetopreventself-fertilization.Thelongandshortpistilsineargrasshavedistinctgeneticdifferencesthatcausethemtobeincompatiblewithpollenfromthesamepistiltype.Thismechanismservestoenhancegeneticdiversityineargrasspopulationsbyreducingthelikelihoodofself-fertilization. Comparisonofmechanisms Bothcrypticandheteromorphicself-incompatibilitymechanismsineargrassservetopromotegeneticdiversityintheplantpopulation.However,crypticself-incompatibilityisasimplemechanismthatinvolvesasinglegene,whereasheteromorphicself-incompatibilityisacomplexmechanismthatinvolvesmultiplegenesanddevelopmentalprocesses. Furthermore,thecrypticmechanismismoreeffectiveinpreventingself-fertilizationthanheteromorphicmechanism,asasinglealleleissufficienttoensureincompatibility.Heteromorphicself-incompatibility,ontheotherhand,requirestwodifferentallelestobepresentineachofthepistiltypesforeffectiveincompatibility