Isolation and Functional Characterization of a LEAFY Gene in Mango (Mangifera indica L.)

Abstract

LEAFY (LFY) plays an important role in the flowering process of plants, controlling flowering time and mediating floral meristem differentiation. Owing to its considerable importance, the mango LFY gene (MiLFY; GenBank accession no. HQ585988) was isolated, and its expression pattern and function were characterized in the present study. The cDNA sequence of MiLFY was 1152 bp, and it encoded a 383 amino acid protein. MiLFY was expressed in all tested tissues and was highly expressed in flowers and buds. Temporal expression analysis showed that MiLFY expression was correlated with floral development stage, and two relative expression peaks were detected in the early stages of floral transition and floral organ differentiation. Moreover, 35S::GFP-MiLFY fusion protein was shown to be localized to the nucleus of cells. Overexpression of MiLFY in Arabidopsis promoted early flowering and the conversion of lateral meristems into terminal flowers. In addition, transgenic plants exhibited obvious morphological changes, such as differences in cauline leaf shape, and the number of lateral branches. When driven by the MiLFY promoter, GFP was highly expressed in leaves, floral organs, stems, and roots, during the flowering period. Exogenous gibberellin (GA3) treatment downregulated MiLFY promoter expression, but paclobutrazol (PPP333) upregulated it. Bimolecular fluorescence complementation (BiFC) assays showed that the MiLFY protein can interact with zinc-finger protein 4 (ZFP4) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (MiSOC1D). Taken together, these results indicate that MiLFY plays a pivotal role in controlling mango flowering, and that it is regulated by gibberellin and paclobutrazol.

Identification of LEAFY gene in longan involved in flower induction

“…Overexpression of VpLFY2 causes precocious owering in Arabidopsis [28]. Similar results were also found in Brassica juncea [29], Jatropha [15], and mango [14]. Consistent with those studies, in the present study, 35S:DlLFY transgenic Arabidopsis lines OE10 and OE11 owered about 4 and 7 days earlier than WT.…”

“…Meanwhile, Arabidopsis lfy mutant shows late owering [7]. Similar phenomena can be found in many plants, including rice (Oryza sativa L.) [16], citrus (Citrus reticulata Blanco) [12], poplar (Populus tomentosa) [17], g (Ficus carica L.) [13], and mango (Mangifera indica L.) [14]. On the contrary, there are also opposite results; for example, overexpression of tobacco LFY homologue NFL1 in Arabidopsis does not severely affect owering [18].…”

“…As with other transcript factors, the number of LFY copies is quite different among species based on differences in gene sequence and protein structure. Usually, plants only have one LFY copy, including Arabidopsis [20], grapevine [21], mango [14], and orange [22]. However, other species contain multiple copies, such as maize [23], pear [24], and loquat [25].…”

“…For example, JcLFY (Jatropha curcas L.) is expressed in in orescence buds, ower buds, and carpels, with the highest expression occurring in the early development stage of ower buds [15]. MiLFY (Mangifera indica L.) was more highly expressed in owers and stems of owering branches than in those of non owering branches, correlated with the oral development stage in different cultivars [14]. LcLFY (Litchi chinensis Sonn.)…”

“…LFY is a plant-speci c transcription factor that can regulate oral meristem and organ formation by binding its target genes, including APETALA1 (AP1), APETALA3 (AP3), CAULIFLOWER (CAL), AGAMOUS (AG), SEPALLATA (SEP), and TERMINAL FLOWER1 (TFL1) [8,9]. Since the rst LEAFY was identi ed in Antirrhinum majus [10], LEAFY homologous genes have been identi ed in several woody plants, including apple [11], citrus [12], g [13], and mango [14]. LFY proteins, which contain conserved C-terminal and N-terminal regions, are highly conserved across plant species.…”