RESUMO
Agapanthus praecox is a monocotyledonous ornamental bulb plant. Generally, the scape (inflorescence stem) length can develop more than 1m, however application 400 mg·L(-1) paclobutrazol can shorten the length beyond 70%. To get a deeper insight into its dwarfism mechanism, de novo RNA-Seq technology has been employed, for the first time, to describe the scape transcriptome of A. praecox. We got 71,258 assembled unigenes, and 45,597 unigenes obtained protein functional annotation. Take the above sequencing results as a reference gene set, using RNA-seq (quantification) technology analyzed gene expression profiles between the control and paclobutrazol-treated samples, and screened 2838 differentially expressed genes. GO, KEGG and MapMan pathway analyses indicated that these differentially expressed genes were significantly enriched in response to stimulus, hormonal signaling, carbohydrate metabolism, cell wall, cell size, and cell cycle related biological process. To validate the expression profiles obtained by RNA-Seq, real-time qPCR was performed on 24 genes selected from key significantly enriched pathways. Comprehensive analysis suggested that paclobutrazol blocks GA signal that can effectively inhibit scape elongation; the GA signal interact with other hormonal signals including auxin, ethylene, brassinosteroid and cytokinins, and trigger downstream signaling cascades leading to metabolism, cell wall biosynthesis, cell division and the cycle decreased obviously, and finally induced dwarfism trait. Furthermore, AP2/EREBP, bHLH, C2H2, ARR, WRKY and ARF family's transcription factors were involved in the regulation of scape development in A. praecox. This transcriptome dataset will serve as an important public information platform to accelerate research on the gene expression and functional genomics of Agapanthus.
Assuntos
Regulação da Expressão Gênica de Plantas/genética , Liliaceae/genética , Caules de Planta/genética , RNA/genética , Transcriptoma/genética , Brassinosteroides/metabolismo , Ciclo Celular/genética , Parede Celular/genética , Citocininas/genética , Etilenos/metabolismo , Perfilação da Expressão Gênica/métodos , Genes de Plantas/genética , Ácidos Indolacéticos/metabolismo , Liliaceae/metabolismo , Anotação de Sequência Molecular/métodos , Proteínas de Plantas/genética , Caules de Planta/crescimento & desenvolvimento , Fatores de Transcrição/genéticaRESUMO
The transition from vegetative to reproductive growth represents a major phase change in angiosperms. Hormones play important roles in this process. In this study, gibberellic acid (GA), cytokinins (CKs), indoleacetic acid (IAA), and abscisic acid (ABA) were analyzed during the flowering in Agapanthus praecox ssp. orientalis. Eleven types of endogenous gibberellins in addition to GA1 were detected in various organs. GA9 was detected with the highest concentrations, followed by GA5, GA8, and GA19. However, GA4 was the main bioactive GA that was involved in the regulation of flowering. Eight types of endogenous cytokinins were detected in A. praecox ssp. orientalis, and zeatin, zeatin riboside, zeatin-O-glucoside, and N(6)-isopentenyladenosine-5-monophosphate were present at higher levels throughout the study, of which zeatin plays an important role in the development of various organs. IAA increased by 581% in the shoot tips from the vegetative to inflorescence bud stages and had the most significant changes during flowering. Phytohormone immunolocalization analysis suggested that IAA involved in differentiation and development of each floral organs, GA and zeatin play important roles in floret primordia differentiation and ovule development. Using exogenous plant growth regulators proved that GA signaling regulate the scape elongation and stimulate early-flowering, and IAA signaling is involved in the pedicel and corolla elongation and delay flowering slightly.
Assuntos
Flores/metabolismo , Giberelinas/metabolismo , Ácidos Indolacéticos/metabolismo , Magnoliopsida/metabolismo , Ácido Abscísico/metabolismo , Citocininas/metabolismo , Flores/crescimento & desenvolvimento , Magnoliopsida/crescimento & desenvolvimentoRESUMO
Comprehensive transcriptomic and proteomic analyses were performed to gain further understanding of the molecular mechanisms of floral initiation in Agapanthus praecox ssp. orientalis. Samples of stem apexes were collected at three different time points including the vegetative, induced, and reproductive period. A total of 374 transcript-derived fragments and 72 proteins showed significant differential expression between the samples. The largest proportion of the identified genes and proteins are involved in metabolism, followed by signal transduction, protein fate, cellular transport, and biogenesis of cellular components. A large number of these genes and proteins were upregulated during the induced and reproductive stages. Their expression profiles demonstrate that carbohydrate metabolism provides nutrients foundation for floral initiation in Agapanthus. Furthermore, a transcription factors GAI (GA insensitive protein) that negatively regulates gibberellin signaling, auxin receptor protein TIR1 (Transport inhibitor response 1), a key enzyme of ethylene biosynthesis SAMS (S-adenosylmethionine synthase), and ethylene receptor protein ETR were isolated and identified. Expression patterns of these proteins, in combination with the results of quantitative phytohormone and immunolocalization analyses, indicated that GA, indole-acetic acid (IAA), and ethylene regulate floral morphogenesis and flowering. In conclusion, these data provide novel insight into the early regulatory steps of flowering in Agapanthus.
