Abstract
The transition from vegetative to reproductive growth in perennial woody plants does not occur until after several years of repeated seasonal changes and alternative growth. To better understand the molecular basis of flowering regulation in citrus, a MADS-box gene was isolated from trifoliate orange (precocious trifoliate orange, Poncirus trifoliata L. Raf.). Sequence alignment and phylogenetic analysis showed that the MADS-box gene is more closely related to the homologs of the AGAMOUS-LIKE 24 (AGL24) lineage than to any of the other MADS-box lineages known from Arabidopsis; it is named PtAGL24. Expression analysis indicated that PtAGL24 was widely expressed in the most organs of trifoliate orange, with the higher expression in mature flowers discovered by real-time PCR. Ectopic expression of PtAGL24 in wild-type Arabidopsis promoted early flowering and caused morphological changes in class I transgenic Arabidopsis. Yeast two-hybrid assay revealed that PtAGL24 interacted with Arabidopsis AtAGL24 and other partners of AtAGL24, suggesting that the abnormal morphology of PtAGL24 overexpression in transgenic Arabidopsis was likely due to the inappropriate interactions between exogenous and endogenous proteins. Also, PtAGL24 interacted with SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (PtSOC1) and APETALA1 (PtAP1) of citrus. These results suggest that PtAGL24 may play an important role in the process of floral transition but may have diverse functions in citrus development.
Highlights
The optimal timing of transition from vegetative to reproductive growth, known as the floral transition, is crucial for successful sexual reproduction of flowering plants
The full length of PtAGL24 was isolated from precocious trifoliate orange by the rapid amplification of cDNA ends (RACE) method
Comparison with other MADS-box proteins included in databases showed that the deduced PtAGL24 had the highest similarity (79% identity) to PtrMADS9 of Populus trichocarpa over the entire coding region, and it shared 60% identity with AtAGL24 (Figure 1A)
Summary
The optimal timing of transition from vegetative to reproductive growth, known as the floral transition, is crucial for successful sexual reproduction of flowering plants. The autonomous and age pathways regulate flowering by monitoring specific developmental states of plants, whereas the gibberellin pathway mediates flowering in non-inductive, shortday conditions (Wang J.-W. et al, 2009; Wang R. et al, 2009; Khan et al, 2014) The interaction among these signaling pathways regulates a group of common targets, the floral pathway integrators, including FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), FLOWERING LOCUS (FLC), and LEAFY (LFY) (Moon et al, 2003; Wigge et al, 2005). An understanding of these different characteristics requires identification and characterization of flowering genes related to these characteristics in woody plants
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
