Transcriptomic Analysis Implies That GA Regulates Sex Expression via Ethylene-Dependent and Ethylene-Independent Pathways in Cucumber (Cucumis sativusL.).
Sex differentiation of flower buds is an important developmental process that directly affects fruit yield of cucumber (Cucumis sativusL.). Plant hormones, such as gibberellins (GAs) and ethylene can promote development of male and female flowers, respectively, however, the regulatory mechanisms of GA-induced male flower formation and potential involvement of ethylene in this process still remain unknown. In this study, to unravel the genes and gene networks involved in GA-regulated cucumber sexual development, we performed high throughout RNA-Seq analyses that compared the transcriptomes of shoot tips between GA3treated and untreated gynoecious cucumber plants. Results showed that GA3application markedly induced male flowers but decreased ethylene production in shoot tips. Furthermore, the transcript levels ofM(CsACS2) gene, ethylene receptorCsETR1and some ethylene-responsive transcription factors were dramatically changed after GA3treatment, suggesting a potential involvement of ethylene in GA-regulated sex expression of cucumber. Interestingly, GA3down-regulated transcript of a C-class floral homeotic gene,CAG2, indicating that GA may also influence cucumber sex determination through an ethylene-independent process. These results suggest a novel model for hormone-mediated sex differentiation and provide a theoretical basis for further dissection of the regulatory mechanism of male flower formation in cucumber.Statement:We reveal that GA can regulate sex expression of cucumber via an ethylene-dependent manner, and theM(CsACS2),CsETR1, andERFsare probably involved in this process. Moreover,CAG2, a C-class floral homeotic gene, may also participate in GA-modulated cucumber sex determination, but this pathway is ethylene-independent.
College of Horticulture, Northwest A&F UniversityYangling, China; State Key Laboratory of Crop Stress Biology in Arid Region, Northwest A&F UniversityYangling, China.
Yan
Y
Zhang
College of Horticulture, Northwest A&F UniversityYangling, China; State Key Laboratory of Crop Stress Biology in Arid Region, Northwest A&F UniversityYangling, China.
Guiye
G
Zhao
College of Horticulture, Northwest A&F UniversityYangling, China; State Key Laboratory of Crop Stress Biology in Arid Region, Northwest A&F UniversityYangling, China.
Yushun
Y
Li
College of Horticulture, Northwest A&F UniversityYangling, China; State Key Laboratory of Crop Stress Biology in Arid Region, Northwest A&F UniversityYangling, China.
Ning
N
Mo
College of Horticulture, Northwest A&F UniversityYangling, China; State Key Laboratory of Crop Stress Biology in Arid Region, Northwest A&F UniversityYangling, China.
Jie
J
Zhang
College of Horticulture, Northwest A&F UniversityYangling, China; State Key Laboratory of Crop Stress Biology in Arid Region, Northwest A&F UniversityYangling, China.
Yan
Y
Liang
cucumber; ethylene; gibberellin; sex expression; transcriptome