TERMINAL FLOWER1 is a breeding target for a novel everbearing trait and tailored flowering responses in cultivated strawberry (Fragaria × ananassa Duch.)

Abstract

SummaryThe effects of daylength and temperature on flowering of the cultivated octoploid strawberry (Fragaria × ananassa Duch.) have been studied extensively at the physiological level, but information on the molecular pathways controlling flowering in the species is scarce. The flowering pathway has been studied at the molecular level in the diploid short‐day woodland strawberry (F. vesca L.), in which the FLOWERING LOCUS T1 (FvFT1)–SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (FvSOC1)–TERMINAL FLOWER1 (FvTFL1) pathway is essential for the correct timing of flowering. In this work, we show by transgenic approach that the silencing of the floral repressor FaTFL1 in the octoploid short‐day cultivar ‘Elsanta’ is sufficient to induce perpetual flowering under long days without direct changes in vegetative reproduction. We also demonstrate that although the genes FaFT1 and FaSOC1 show similar expression patterns in different cultivars, the regulation of FaTFL1 varies widely from cultivar to cultivar and is correlated with floral induction, indicating that the transcription of FaTFL1 occurs at least partially independently of the FaFT1–FaSOC1 module. Our results indicate that changing the expression patterns of FaTFL1 through biotechnological or conventional breeding approaches could result in strawberries with specific flowering and runnering characteristics including new types of everbearing cultivars.

Narrowing down the single homoeologous FaPFRU locus controlling flowering in cultivated octoploid strawberry using a selective mapping strategy

“…We and others previously showed that a two-bp mutation in FvKSN, a strawberry ortholog of the TERMINAL FLOWER 1 (TFL1) floral repressor, was responsible for the PF trait in diploid strawberry (Iwata et al, 2012;Koskela et al, 2012). The role of TFL1 as a floral repressor in the cultivated octoploid strawberry was also recently confirmed by Koskela et al (2016). In this study, silencing the floral repressor FaTFL1 in a SF cultivar through a transgenic approach was sufficient to induce PF under long days.…”

“…The role of TFL1 as a floral repressor in the cultivated octoploid strawberry was also recently confirmed by Koskela et al . (). In this study, silencing the floral repressor FaTFL1 in a SF cultivar through a transgenic approach was sufficient to induce PF under long days.…”

Altered regulation of TERMINAL FLOWER 1 causes the unique vernalisation response in an arctic woodland strawberry accession

“…In both diploid (FIN56) and octoploid species of Fragaria , SDs and/or low temperatures of c . 10–13°C downregulate TFL1 (Nakano et al ., ; Rantanen et al ., ; Koskela et al ., ). Regulation of FvTFL1 in the arctic accession NOR1 contrasted with these earlier findings, as FvTFL1 expression was not suppressed as a response to SDs and 11°C (Fig.…”

“…SYBR Green I master mix (Roche Deutschland Holding GmbH) was used for 10 μl real‐time PCR reactions and run in a LightCycler 480 instrument (Roche) as described by Koskela et al . (). Three technical and three biological replicates were performed using the primers listed in Table S2.…”

“…RNA was extracted using the pine tree method (Monte & Somerville, 2002), treated with rDNase (Macherey-Nagel GmbH, D€ uren, Germany) according to the manufacturer's recommendations, and cDNA was synthesised from 500 ng total-RNA using Superscript III reverse transcriptase (Invitrogen, Thermo Fisher Scientific). SYBR Green I master mix (Roche Deutschland Holding GmbH) was used for 10 ll real-time PCR reactions and run in a LightCycler 480 instrument (Roche) as described by Koskela et al (2016). Three technical and three biological replicates were performed using the primers listed in Table S2.…”