The TFL1 homologue KSN is a regulator of continuous flowering in rose and strawberry

Flowering is a key event in plant life, and is finely tuned by environmental and endogenous signals to adapt to different environments. In horticulture, continuous flowering (CF) is a popular trait introduced in a wide range of cultivated varieties. It played an essential role in the tremendous success of modern roses and woodland strawberries in gardens. CF genotypes flower during all favourable seasons, whereas once-flowering (OF) genotypes only flower in spring. Here we show that in rose and strawberry continuous flowering is controlled by orthologous genes of the TERMINAL FLOWER 1 (TFL1) family. In rose, six independent pairs of CF/OF mutants differ in the presence of a retrotransposon in the second intron of the TFL1 homologue. Because of an insertion of the retrotransposon, transcription of the gene is blocked in CF roses and the absence of the floral repressor provokes continuous blooming. In OF-climbing mutants, the retrotransposon has recombined to give an allele bearing only the long terminal repeat element, thus restoring a functional allele. In OF roses, seasonal regulation of the TFL1 homologue may explain the seasonal flowering, with low expression in spring to allow the first bloom. In woodland strawberry, Fragaria vesca, a 2-bp deletion in the coding region of the TFL1 homologue introduces a frame shift and is responsible for CF behaviour. A diversity analysis has revealed that this deletion is always associated with the CF phenotype. Our results demonstrate a new role of TFL1 in perennial plants in maintaining vegetative growth and modifying flowering seasonality

Molecular diversity of anthracnose pathogen populations associated with UK strawberry production suggests multiple introductions of three different Colletotrichum species.

Fragaria × ananassa (common name: strawberry) is a globally cultivated hybrid species belonging to Rosaceae family. Colletotrichum acutatum sensu lato (s.l.) is considered to be the second most economically important pathogen worldwide affecting strawberries. A collection of 148 Colletotrichum spp. isolates including 67 C. acutatum s.l. isolates associated with the phytosanitary history of UK strawberry production were used to characterize multi-locus genetic variation of this pathogen in the UK, relative to additional reference isolates that represent a worldwide sampling of the diversity of the fungus. The evidence indicates that three different species C. nymphaeae, C. godetiae and C. fioriniae are associated with strawberry production in the UK, which correspond to previously designated genetic groups A2, A4 and A3, respectively. Among these species, 12 distinct haplotypes were identified suggesting multiple introductions into the country. A subset of isolates was also used to compare aggressiveness in causing disease on strawberry plants and fruits. Isolates belonging to C. nymphaeae, C. godetiae and C. fioriniae representative of the UK anthracnose pathogen populations showed variation in their aggressiveness. Among the three species, C. nymphaeae and C. fioriniae appeared to be more aggressive compared to C. godetiae. This study highlights the genetic and pathogenic heterogeneity of the C. acutatum s.l. populations introduced into the UK linked to strawberry production

Genetic dissection of fruit quality traits in the octoploid cultivated strawberry highlights the role of homoeo-QTL in their control

Fruit quality traits are major breeding targets in the Rosaceae. Several of the major Rosaceae species are current or ancient polyploids. To dissect the inheritance of fruit quality traits in polyploid fleshy fruit species, we used a cultivated strawberry segregating population comprising a 213 full-sibling F1 progeny from a cross between the variety ‘Capitola’ and the genotype ‘CF1116’. We previously developed the most comprehensive strawberry linkage map, which displays seven homoeology groups (HG), including each four homoeology linkage groups (Genetics 179:2045–2060, 2008). The map was used to identify quantitative trait loci (QTL) for 19 fruit traits related to fruit development, texture, colour, anthocyanin, sugar and organic acid contents. Analyses were carried out over two or three successive years on field-grown plants. QTL were detected for all the analysed traits. Because strawberry is an octopolyploid species, QTL controlling a given trait and located at orthologous positions on different homoeologous linkage groups within one HG are considered as homoeo-QTL. We found that, for various traits, about one-fourth of QTL were putative homoeo-QTL and were localised on two linkage groups. Several homoeo-QTL could be detected the same year, suggesting that several copies of the gene underlying the QTL are functional. The detection of some other homoeo-QTL was year-dependent. Therefore, changes in allelic expression could take place in response to environmental changes. We believe that, in strawberry as in other polyploid fruit species, the mechanisms unravelled in the present study may play a crucial role in the variations of fruit quality

2D representation of the plant architecture in strawberry

International audienceThe development of soilless cultivation for strawberry production is a current major socio-economic issue. This technique improves competitiveness by early planting (December) in heated greenhouses, allowing an extension of flowering and thus of fruit production. Our objective is to better understand the strategy of different cultivars to extend flowering by studying the spatiotemporal development of plant architecture. In a previous phenological study, specific flowering patterns were identified in six cultivated varieties (Labadie et al., 2019). Here, we designed a 2D visualization and an analysis approach to represent the plant architecture and its development. Our analysis approach was applied in six strawberry cultivars. Subsets of plants were dissected at successive dates during the season in order to understand the architectural development. All structures (buds, order of the axes, number of leaves on each axis, etc.) were described. Results showed architectural patterns are highly conserved in genotypes and differ in the rate of architecture formation. All genotypes had a higher number of leaves and of flowers on the axis of order 0 (main crown or primary crown). These numbers decreased sharply in axes of order 1 (axes produced by axillary meristems present on the axis of order 0) and continued to decrease in axes of orders >=2 for flowers by inflorescences. Our 2D visualization can be further used in breeding programs to evaluate cultivars

Bioactive compounds in berries relevant to human health

Berries contain powerful antioxidants, potential allergens, and other bioactive compounds. Genetic and environmental factors affect production and storage of such compounds. For this reason breeding and biotechnological approaches are currently used to control or to increase the content of specific health-related compounds in fruits. This work reviews the main bioactive compounds determining the nutritional quality of berries, the major factors affecting their content and activity, and the genetic options currently available to achieve new genotypes able to provide, under controlled cultivation conditions, berries with the proper balance of bioactive compounds for improving consumer healt

Isolation and phenotypical characterization of the FT-like genes in strawberry (Fragaria × ananassa)

Plant FLOWERING LOCUS T (FT) homologous play key roles in flowering cycle and during various developmental processes. So far, there has still been limited research on flowering processes and regulations in the octoploid strawberry. In this study, the orthologues of the FLOWERING LOCUS T (FT) genes, including FvFT2 and FvFT3 from Fragaria vesca (diploid), were isolated and characterized by Agrobacterium-mediated transformation in the octoploid strawberry cultivar 'Sveva' (June-bearing). Four and three transgenic lines of 'Sveva', transformed with the two different FT-like genes (FvFT2 and FvFT3), respectively, were in vitro elongated and acclimatized in the greenhouse. Preliminary results showed that the plant architecture of the transgenic lines obtained was significantly different compared to the wild-type controls. The overexpression of the two FT-like genes in the transgenic lines resulted in the balance between sexual/asexual reproduction patterns. Our investigation suggests that FvFT2 gene has positive effect on the flowering promotion, and FvFT3 gene on stolons production

Isolation and phenotypical characterization of the FT -like genes in strawberry ( Fragaria × ananassa )

Plant FLOWERING LOCUS T (FT) homologous play key roles in flowering cycle and during various developmental processes. So far, there has still been limited research on flowering processes and regulations in the octoploid strawberry. In this study, the orthologues of the FLOWERING LOCUS T (FT) genes, including FvFT2 and FvFT3 from Fragaria vesca (diploid), were isolated and characterized by Agrobacterium-mediated transformation in the octoploid strawberry cultivar 'Sveva' (June-bearing). Four and three transgenic lines of 'Sveva', transformed with the two different FT-like genes (FvFT2 and FvFT3), respectively, were in vitro elongated and acclimatized in the greenhouse. Preliminary results showed that the plant architecture of the transgenic lines obtained was significantly different compared to the wild-type controls. The overexpression of the two FT-like genes in the transgenic lines resulted in the balance between sexual/asexual reproduction patterns. Our investigation suggests that FvFT2 gene has positive effect on the flowering promotion, and FvFT3 gene on stolons production

Bioactivities of berries relevant to human health

Rewie

European small berries genetic resources, GENBERRY: testing a protocol for detecting fruit nutritional quality in EU strawberry germplasm collections

International audienceThe objective of the EU GENBERRY project is to ensure that agricultural biodiversity of small berries, strawberry and red raspberry, is preserved and characterized for using them in further breeding programs. This project is based on the notion of networking, considering that maximum added-value can only be reached by bringing together otherwise rather scattered competences on techniques of cultivation, phenotypic description, molecular biology, as well as evaluation for health value compounds and disease resistance. This project involves ten partners located in eight European countries (France, Italy, Germany, Great Britain, Lithuania, Poland, Romania and Spain). This paper describes the work finalized to the evaluation of strawberry germplasm fruit nutritional quality, in particular the analytical protocols identified for the study of the bioactive compounds of strawberry accessions and their application and validation in fruit of a cultivar ('Clery') grown in 3 different collections in Europe