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

Abstract

Vernalisation requirement is an agriculturally important trait that postpones the development of cold-sensitive floral organs until the spring. The family Rosaceae includes many agriculturally important fruit and berry crops that suffer from crop losses caused by frost injury to overwintering flower buds. Recently, a vernalisation-requiring accession of the Rosaceae model woodland strawberry (Fragaria vesca) has been identified in northern Norway. Understanding the molecular basis of the vernalisation requirement in this accession would advance the development of strawberry cultivars better adapted to temperate climate. We use gene silencing, gene expression analysis, genetic mapping and population genomics to study the genetic basis of the vernalisation requirement in woodland strawberry. Our results indicate that the woodland strawberry vernalisation requirement is endemic to northern Norwegian population, and mapping data suggest the orthologue of TERMINAL FLOWER1 (FvTFL1) as the causal floral repressor. We demonstrate that exceptionally low temperatures are needed to downregulate FvTFL1 and to make these plants competent to induce flowering at low postvernalisation temperatures in the spring. We show that altered regulation of FvTFL1 in the northern Norwegian woodland strawberry accession postpones flower induction until the spring, allowing plants to avoid winter injuries of flower buds that commonly occur in temperate regions.

Low night temperatures during the early growth phase enhance flowering in primocane shoots of red raspberries (Rubus idaeus L.)

“…RiTFL repression may have favoured early flowering in this trial, and plants developed more reproductive buds before entering recess. This agrees with the results of [15], who demonstrated that low temperatures are necessary to suppress TFL1 in Fragaria vesca, enabling the plants to induce flowering.…”

“…Vernalisation, the process by which low temperatures favour inception of the reproductive stage [14], is an adaptation mechanism to temperate climates in some species which require a cold period during plant development before being receptive to another signal for floral induction [15,16]. In the cultivar 'Heritage', the need for vernalisation in seasonal shoots may explain the differences in fruiting traits in different climatic environments.…”

“…In this species, prolonged cold treatments can reverse late flowering [20]. This response to vernalisation has revealed specific repressor genes for each species, which can be inactivated with periods of cold exposure, thus inducing flowering [15].…”

Control of Flowering and Runnering in Strawberry

“…According to molecular studies, seasonal cycling of FvTFL1 mRNA expression at the shoot apical meristem causes typical seasonal flowering habit of woodland strawberry (Koskela et al, 2012(Koskela et al, , 2017. In LDs of summer, high FvTFL1 mRNA level maintains the vegetative apical meristem, while the downregulation of the…”

Allelic Variation ofMYB10is the Major Force Controlling Natural Variation of Skin and Flesh Color in Strawberry (Fragariaspp.) fruit

“…Whole genome resequencing of FIN12 accession was carried out at DNA Sequencing and Genomics Laboratory, Institute of Biotechnology, University of Helsinki, Finland using Illumina NextSeq 500 sequencer. Library preparation, pairend sequencing (150 + 150 bp), and the alignment of the sequencing reads on the F. vesca H4 reference genome v4.1 (Edger et al, 2018) was carried out as described earlier (Koskela et al, 2017). Sequencing data is stored at NCBI Short Read Archive (https://www.ncbi.nlm.nih.gov/sra) under the accession number XXXXXX.…”