The MdTFL1 gene of apple (Malus x domestica Borkh.) reduces vegetative growth and generation time

Abstract

TFL1 is known as a floral repressor in Arabidopsis thaliana (L.) Heynh. In apple there are two TFL1 homologs, MdTFL1-1 and MdTFL1-2. The MdTFL1-1 gene was silenced in transgenic clones expressing a hairpin gene construct of a 323 bp fragment of MdTFL1-1. The hairpin gene construct was transferred to three different apple genotypes. Of 22 transgenic clones, 21 showed a significant reduction in MdTFL1-1 mRNA expression. Precocious flowering was obtained for 20 clones, which flowered already during in vitro cultivation. Nineteen clones could successfully be transferred to the greenhouse where 18 of them flowered within a few weeks followed by the death or at least a strongly inhibited vegetative growth of the plant. Most of the transgenic flowers developed abnormally. Results obtained on greenhouse-grown plants of the transgenic clones and transgenic seedlings clearly demonstrated the major role of MdTFL1 genes in maintaining the vegetative growth as prerequisite for a perennial lifecycle. It was shown that MdTFL1 dsRNAi promotes a life history similar to annual plants. Preliminary results obtained from grafting experiments with non-transgenic scions grafted onto MdTFL1 dsRNAi transgenic rootstocks indicated that the flower-inducing signal obtained after silencing of MdTFL1 genes seems not to be graft-transmissible.

The JatrophaFT ortholog is a systemic signal regulating growth and flowering time

“…Flower initiation has been intensively studied in Arabidopsis, and orthologs/homologs of genes for LFY, AP1, and TFL1 have been cloned from apple trees among others [23][24][25]. There are a few successful reports on a rapid breeding program in apple by genetic modification of the flowering pathway [26][27][28]. A similar strategy can be used in breeding programs of Jatropha.…”

Transcriptome analysis provides insights into wood formation during larch tree aging

“…In studies of the molecular mechanisms of tree aging, many age-related genes have been identified (Busov et al 2004;Carlsbecker et al 2004;Diego et al 2004;Fernández-Ocaña et al 2010;García-López et al 2014;Hutchison et al 1990;Li et al 2010Xu et al 2016;Zhang et al 2016), such as miR156 (Wang et al 2011b) and Flowering Locus T (Böhlenius et al 2006;Hsu et al 2006Hsu et al , 2011, and some have been used to change the agronomic traits of plants (Flachowsky et al 2012;Kotoda et al 2006;Li et al 2013a;Yamagishi et al 2014). Larix kaempferi is a forest tree of important ecological and economic value, widely grown in the Northern Hemisphere, but its genome has not been sequenced.…”

Virus-Induced Flowering: An Application of Reproductive Biology to Benefit Plant Research and Breeding

“…TERMINAL FLOWER1 (TFL1) is in the same gene family as FT, but TFL1 (and homologs) acts as a competitive inhibitor of FT (Hanano and Goto, 2011;Ho and Weigel, 2014;Lifschitz et al, 2014). Consequently, either FT gain of function or TFL1 loss of function results in more determinate growth and faster transition to reproductive growth (Flachowsky et al, 2012;Freiman et al, 2012). Other genes in the flowering pathway are used similarly as breeding tools to accelerate flowering; for example, apple transformed with a flowering-associated MADS box gene from silver birch (Betula spp.…”