Molecular and Functional Characterization of FLOWERING LOCUS T Homologs in Allium cepa

Abstract

Abstract:Onion bulbing is an important agricultural trait affecting economic value and is regulated by flowering-related genes. FLOWERING LOCUS T (FT)-like gene function is crucial for the initiation of flowering in various plant species and also in asexual reproduction in tuber plants. By employing various computational analysis using RNA-Seq data, we identified eight FT-like genes (AcFT) encoding PEBP (phosphatidylethanolamine-binding protein) domains in Allium cepa. Sequence and phylogenetic analyses of FT-like proteins revealed six proteins that were identical to previously reported AcFT1-6 proteins, as well as one (AcFT7) with a highly conserved region shared with AcFT6 and another (comp106231) with low similarity to MFT protein, but containing a PEBP domain. Homology modelling of AcFT7 proteins showed similar structures and conservation of amino acids crucial for function in AtFT (Arabidopsis) and Hd3a (rice), with variation in the C-terminal region. Further, we analyzed AcFT expression patterns in different transitional stages, as well as under SD (short-day), LD (long-day), and drought treatment in two contrasting genotypic lines EM (early maturation, 36101) and LM (late maturation, 36122). The FT transcript levels were greatly affected by various environmental factors such as photoperiod, temperature and drought. Our results suggest that AcFT7 is a member of the FT-like genes in Allium cepa and may be involved in regulation of onion bulbing, similar to other FT genes. In addition, AcFT4 and AcFT7 could be involved in establishing the difference in timing of bulb maturity between the two contrasting onion lines.

Evolution and Expression of Reproductive Transition Regulatory Genes FT/TFL1 With Emphasis in Selected Neotropical Orchids

“…Expression analyses of FT-like homologs from the FT2 clade have identified active transcription of MonFT2 members in leaves, SAM, IM, FBs, and fruits. These patterns are consistently found in Asparagales (Allium cepa), Liliales (Lilium longiflorum and Tulipa gesneriana), Orchidaceae (Cymbidium goeringii, Dendrobium "Chao Praya Smile, " Dendrobium nobile, Oncidium Gower Ramsey, Phalaenopsis aphrodite, Phalaenopsis "Thailin Red Angel V31, " Phalaenopsis "Fortune Saltzman"), Poales (Zea mays) and Zingiberales (Musa acuminata) (Danilevskaya et al, 2008;Hou and Yang, 2009;Li et al, 2012Li et al, , 2014Xiang et al, 2012;Lee et al, 2013;Jang et al, 2015;Manoharan et al, 2016;Chaurasia et al, 2017;Wang et al, 2017;Leeggangers et al, 2018;Zhou et al, 2018). In addition, FT2 homologs from A. cepa and Oncidium "Gower Ramsey" have also been detected in bulbs and pseudobulbs, respectively (Hou and Yang, 2009;Lee et al, 2013;Manoharan et al, 2016).…”

“…The expression of MonFT1 genes (i.e., those that nest in the MonFT1 clade in our analysis) has been less studied in orchids when compared to MonFT2 genes. MonFT1 transcripts have been isolated from leaves, IM as well as young and old FBs in Allium cepa (Asparagaceace), Tulipa gesneriana (Liliaceae), Phalaenopsis Tailin Red Angel V31 (Orchidaceae), Zea mays (Poaceae), and Musa acuminata (Musaceae) (Danilevskaya et al, 2008;Lee et al, 2013;Manoharan et al, 2016;Chaurasia et al, 2017;Leeggangers et al, 2018;Zhou et al, 2018). Only rarely they have been isolated from SAMs, stems and roots in T. gesneriana and Z. mays (Danilevskaya et al, 2008;Leeggangers et al, 2018), as well as from the bulb of A. cepa (Lee et al, 2013;Manoharan et al, 2016).…”

Crosstalk in the darkness: bulb vernalization activates meristem transition via circadian rhythm and photoperiodic pathway

“…Our present results show that similar to onion, in garlic low temperatures affect down-regulation of AsFT4 and up-regulation of AsFT2. Differences in FT expression between short-and long-day onion varieties were already shown [56,57]. Since in vernalized garlic bulbing is also possible under short day, FT genes in this species can express and function in different manner, and further functional characterization of this family in various garlic genotypes will help to understand their role in florogenesis and bulbing.…”

Improvement of alfalfa forage quality and management through the down‐regulation of MsFTa1

“…In soybean (Glycine max), approximately 10 homologues of FT have been identified (Kong et al, 2010), with 6 of them having roles in flowering induction (Fan et al, 2014;Kong et al, 2010) and one as a flowering repressor (Zhai et al, 2014). In Pisum sativum and Medicago truncatula, five homologues of FT were identified Laurie et al, 2011) and, among them, only two are strong flowering inducers, suggesting that there may be additional subfunctionalization among the other FT-like genes, as is the case in other species (Manoharan et al, 2016;Navarro et al, 2011).…”