EjTFL1 Genes Promote Growth but Inhibit Flower Bud Differentiation in Loquat

Abstract

TERMINAL FLOWER1 (TFL1), a key factor belonging to the phosphatidyl ethanolaminebinding protein (PEBP) family, controls flowering time and inflorescence architecture in some plants. However, the role of TFL1 in loquat remains unknown. In this study, we cloned two TFL1-like genes (EjTFL1-1 and EjTFL1-2) with conserved deduced amino acid sequences from cultivated loquat (Eriobotrya japonica Lindl.). First, we determined that flower bud differentiation occurs at the end of June and early July, and then comprehensively analyzed the temporal and spatial expression patterns of these EjTFL1s during loquat growth and development. We observed the contrasting expression trends for EjTFL1s and EjAP1s (APETALA 1) in shoot apices, and EjTFL1s were mainly expressed in young tissues. In addition, short-day and exogenous GA 3 treatments promoted the expression of EjTFL1s, and no flower bud differentiation was observed after these treatments in loquat. Moreover, EjTFL1s were localized to the cytoplasm and nucleus, and both interacted with another flowering transcription factor, EjFD, in the nucleus, and EjTFL1s-EjFD complex significantly repressed the promoter activity of EjAP1-1. The two EjTFL1s were overexpressed in wild-type Arabidopsis thaliana Col-0, which delayed flowering time, promoted stem elongation, increased the number of branches, and also affected flower and silique phenotypes. In conclusion, our results suggested that EjTFL1-1 and EjTFL1-2 do not show the same pattern of expression whereas both are able of inhibiting flower bud differentiation and promoting vegetative growth in loquat by integrating GA 3 and photoperiod signals. These findings provide useful clues for analyzing the flowering regulatory network of loquat and provide meaningful references for flowering regulation research of other woody fruit trees.

The Overexpression of Four MiTFL1 Genes from Mango Delays the Flowering Time in Transgenic Arabidopsis

“…EjTFL1-1 is mainly expressed in roots and leaf buds but is expressed at low levels in shoots, ower buds and owers. EjTFL1-2 is mainly expressed in leaf buds, owers, and fruits and is not expressed in the other tissues [30]. In the present study, MiTFL1 genes showed different expression patterns than those reported above.…”

“…In the present study, four TFL1 genes were obtained from 'SiJiMi' mango, and these were named MiTFL1-1, MiTFL1-2, MiTFL1-3 and MiTFL1-4. Multiple copies of TFL1 homologous genes were also found in other plants, such as two in soybean [29], moso bamboo [13] and loquat [30], three in petunia [31], four in cotton [32] and ve in Hevea brasiliensis [33]. In a previous study, only two TFL1 genes, MiTFL1 and MiTFL1a, were found in another mango variety, 'Alphonso', and these corresponded to MiTFL1-2 and MiTFL1-1 in the present study, respectively [34].…”

“…In Hevea brasiliensis, HbTFL1-1, HbTFL1-2 and HbTFL1-3 expression increases gradually during in orescence development, but HbCEN1 and HbCEN2 continuously decreases over this period [39]. The expression levels of EjTFL1-1 and EjTFL1-2 gradually decrease before oral bud differentiation and started to increase again during the ower-opening period [30]. In the mango variety 'Alphonso', MiTFL1 expression increases during the owering induction period and subsequently decreases, whereas MiTFL1a expression remains low during the owering period [34].…”

Overexpression of four MiTFL1 genes from mango delays the flowering time in transgenic Arabidopsis

“…Multiple copies of TFL1 homologous genes are also found in other plants, such as two in soybean [ 30 ], moso bamboo [ 13 ] and loquat [ 31 ], three in petunia [ 32 ], four in cotton [ 33 ] and five in Hevea brasiliensis [ 34 ]. In a previous study, only two TFL1 genes, namely, MiTFL1 and MiTFL1a, were found in another mango variety, ‘ Alphonso ’, corresponding to MiTFL1-2 and MiTFL1-1 , respectively, in the present study [ 35 ].…”

Sorbitol in loquat promotes early flower bud differentiation via the MADS-box transcription factor EjCAL

“…Therefore, FBD and the blooming time affect the fruit yield and quality. Although several genes related to flower development in cultivated loquat, such as EjLFY, EjAP1, EjFT, EjSOC, EjTFL1 , and EjAGL17 have been cloned (Esumi et al, 2005; Liu et al, 2013; Reig et al, 2017; Jiang et al, 2019; Jiang et al, 2020; Xia et al, 2020), the mechanism of FBD in loquat remains unclear.…”