RESUMO
Jatropha curcas (J. curcas) is a perennial oil-seed plant with vigorous vegetative growth but relatively poor reproductive growth and low seed yield. Gibberellins (GAs) promotes flowering in most annual plants but inhibits flowering in many woody plants, including J. curcas. However, the underlying mechanisms of GA inhibits flowering in perennial woody plants remain unclear. Here, we found that overexpression of the GA biosynthesis gene JcGA20ox1 inhibits flowering in J. curcas and in J. curcas × J. integerrima hybrids. Consistent with this finding, overexpression of the GA catabolic gene JcGA2ox6 promotes flowering in J. curcas. qRTPCR revealed that inhibits floral transition by overexpressing JcGA20ox1 resulted from a decrease in the expression of JcFT and other flowering-related genes, which was restored by overexpressing JcFT in J. curcas. Overexpression of JcGA20ox1 or JcGA2ox6 reduced seed yield, but overexpression of JcFT significantly increased seed yield. Furthermore, hybridization experiments showed that the reduction in seed yield caused by overexpression of JcGA20ox1 or JcGA2ox6 was partially restored by the overexpression of JcFT. In addition, JcGA20ox1, JcGA2ox6 and JcFT were also found to be involved in the regulation of seed oil content and endosperm development. In conclusion, our study revealed that the inhibitory effect of GA on flowering is mediated through JcFT and demonstrated the effects of JcGA20ox1, JcGA2ox6 and JcFT on agronomic traits in J. curcas. This study also indicates the potential value of GA metabolism genes and JcFT in the breeding of new varieties of woody oil-seed plants.
Assuntos
Flores , Giberelinas , Jatropha , Proteínas de Plantas , Giberelinas/metabolismo , Flores/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Jatropha/genética , Jatropha/metabolismo , Jatropha/crescimento & desenvolvimento , Jatropha/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/genética , Sementes/genética , Sementes/crescimento & desenvolvimento , Sementes/metabolismoRESUMO
Production of normal gametes is necessary for flowering plant reproduction, which involves the transition from vegetative to reproductive stage and floral organ development. Such transitions and floral development are modulated by various environmental and endogenous stimuli and controlled by sophisticated regulatory networks. FLOWERING LOCUS T (FT) and LEAFY (LFY) are two key genes that integrate signals from multiple genetic pathways in Arabidopsis. However, the comprehensive functions and relationship between these two genes in trees are poorly understood. In this study, we found that JcFT played a vital role in regulating the flowering transition in the perennial woody species Jatropha curcas. JcLFY also involved in regulating this transition and controlled floral organ development. The non-flowering phenotype of JcFT-RNAi was rescued successfully by overexpression of JcLFY, while the abnormal flowers produced by JcLFY silencing were not recovered by JcFT overexpression via hybridization. These results indicate that JcFT, in which a mutation leads to a nonflowering phenotype, is the central gene of the floral meristem transition and that JcLFY, in which a mutation leads to striking changes in flowering and often sterility, is the central floral and inflorescence development gene. Moreover, our hybridization results suggest that JcLFY acts downstream of JcFT in Jatropha.