title: A putative positive feedback regulation mechanism in CsACS2 expression suggests a modified model for sex determination in cucumber (Cucumis sativus L.).
abstract: It is well established that the plant hormone ethylene plays a key role in cucumber sex determination. Since the unisexual control gene M was cloned and shown to encode an ethylene synthase, instead of an ethylene receptor, the 'one-hormone hypothesis', which was used to explain the cucumber sex phenotype, has been challenged. Here, the physiological function of CsACS2 (the gene encoded by the M locus) was studied using the transgenic tobacco system. The results indicated that overexpression of CsACS2 increased ethylene production in the tobacco plant, and the native cucumber promoter had no activity in transgenic tobacco (PM). However, when PM plants were treated with exogenous ethylene, CsACS2 expression could be detected. In cucumber, ethylene treatment could also induce transcription of CsACS2, while inhibition of ethylene action reduced the expression level. These findings suggest a positive feedback regulation mechanism for CsACS2, and a modified 'one-hormone hypothesis' for sex determination in cucumber is proposed.
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.forename: Qianyi
authors.initials: Q
authors.lastname: Tao
authors.forename: Junsong
authors.initials: J
authors.lastname: Pan
authors.forename: Longting
authors.initials: L
authors.lastname: Si
authors.forename: Zhenhui
authors.initials: Z
authors.lastname: Gong
authors.forename: Run
authors.initials: R
authors.lastname: Cai
mesh_terms: D001483:Base Sequence; D018553:Cucumis sativus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D018744:DNA, Plant / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism / Q000494:pharmacology*; D035264:Flowers / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D056130:Gametogenesis, Plant / Q000187:drug effects / Q000235:genetics*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D017422:Sequence Analysis, DNA; D012835:Silver Nitrate / Q000494:pharmacology; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology
chemical_list: D018744:DNA, Plant; D005030:Ethylenes; D009943:Organophosphorus Compounds; D010937:Plant Growth Regulators; D010940:Plant Proteins; C036216:ethylene; D012835:Silver Nitrate; C005073:ethephon