Abstract
Recent research revealed that TERMINAL FLOWER 1 (TFL1) homologues are involved in the critical developmental process of floral initiation in several plant species. In this study, the functions of three putative TFL1 homologues (JcTFL1a, JcTFL1b and JcTFL1c) in the biofuel plant Jatropha curcas were analysed using the transgenic approach. JcTFL1b and JcTFL1c, but not JcTFL1a, could complement the TFL1 function and rescue early flowering and determinate inflorescence phenotype in tfl1-14 Arabidopsis mutant, thus suggesting that JcTFL1b and JcTFL1c may be homologues of TFL1. Transgenic Jatropha overexpressing JcTFL1a, JcTFL1b or JcTFL1c showed late flowering, whereas only JcTFL1b and JcTFL1c overexpression delayed flowering in transgenic Arabidopsis. JcTFL1b-RNAi transgenic Jatropha consistently exhibited moderately early flowering phenotype. JcFT and JcAP1 were significantly downregulated in transgenic Jatropha overexpressing JcTFL1a, JcTFL1b or JcTFL1c, which suggested that the late flowering phenotype of these transgenic Jatropha may result from the repressed expression of JcFT and JcAP1. Our results indicate that these three JcTFL1 genes play redundant roles in repressing flowering in Jatropha.
Highlights
Floral initiation, a key developmental process in higher plant life, involves transition from vegetative to reproductive growth
To determine the effects of JcTFL1 genes on flowering time and inflorescence architecture, JcTFL1a, JcTFL1b and JcTFL1c cDNA driven by the constitutive 35S promoter were transformed into WT Arabidopsis plants, respectively
AtAP1 was significantly downregulated in the 35S::JcTFL1b and 35S::JcTFL1c transgenic lines (Supplementary Fig. S2E), which was consistent with the late flowering phenotype
Summary
A key developmental process in higher plant life, involves transition from vegetative to reproductive growth. In Arabidopsis, the floral induction signals from these five major flowering pathways are transmitted via floral integrator genes, such as FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FLOWERING LOCUS C (FLC), to the floral meristem identity genes LEAFY (LFY) and APETALA1 (AP1) at the apical meristem[6,7,8,9]. FT promotes flowering initiation, whereas TFL1 acts as a repressor for floral initiation and maintains the inflorescence meristem through suppression of the expression of LFY and AP112–15. Constitutive expression of CsTFL1 in chrysanthemums resulted in extremely late flowering and prevented upregulation of floral meristem identity genes in shoot tips and leaves[3].
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