Biology subjects

Olbricht, K.

Publications and source records attributed to Olbricht, K..

5 recordsLinked to original sources

bioRxiv2024

Late Quaternary climatic impact on the woodland strawberry genome: a perennial herb's tale

Exploring a species paleohistory is crucial for understanding its responsiveness to climatic events, identifying drivers of adaptation, and developing effective biodiversity conservation strategies in the face of ongoing climate change. We analyzed 200 genomes of the perennial herb woodland strawberry (Fragaria vesca L.) from across Europe and investigated the population structure and demographic history of the species during past geoclimatic events. We found a clear division of populations into western and eastern genetic clusters, indicative of distinct glacial refugia and adaptations to variation in temperature seasonality. The eastern core populations were several times larger (defined as effective population size, NE) than populations in other regions, showed no evidence of inbreeding, and were resilient to several glacial maxima. However, we observed decreasing NE and higher inbreeding in populations toward range edges, particularly in the north, where these individuals went through bottlenecks during glaciations. Population divergence suggested that western and eastern Europe were colonized from separate refugia in multiple waves during the Holocene, while the largest current populations from the northern Mediterranean to southern regions of the Nordic countries formed a connected population chain with gene flow between eastern core populations and western Europe, primarily occurring through Central Europe. Similar patterns of colonization and hybridization may have occurred during past interglacial periods, contributing to the present-day population structure of woodland strawberry. We suggest that the unprecedented resolution of the species climatic history across six glacial-interglacial cycles presented here holds the promise of transforming the general understanding of species paleohistory through geoclimatically tracing ancestral haplotypes.

plant biology↗

bioRxiv2024

Differential expression ofCCD4(4B) drives natural variation in fruit carotenoidcontent in strawberry ( Fragaria spp.)

Pigments, mainly anthocyanins and carotenoids, are important contributors to fruits visual appearance and nutritional properties. In strawberry (Fragaria spp.), the genetic and molecular mechanisms regulating fruit carotenoid biosynthesis and its natural variation remain largely unexplored. In this study, we sought to identify genomic loci contributing to variation in yellow flesh pigmentation. A major QTL, qYellow Flesh-4B, accounting for 82% of the total phenotypic variation was identified on F. x ananassa chromosome 4B. Following a candidate gene approach, we determined that CCD4(4B), a carotenoid cleavage dioxygenase (CCD), was the underlying gene. Specific polymorphisms on CCD4(4B) promoter region were associated with the yellow flesh phenotype and with differential regulation of CCD4(4B) expression during fruit ripening. Furthermore, CCD4(4B) expression levels were negatively correlated with violaxanthin, lutein, zeaxanthin, {beta}-carotene and total carotenoid content. The role of CCD4(4B) in carotenoid turnover was confirmed by transient overexpression in F. x ananassa fruits, which led to a decrease in carotenoid accumulation. Notably, a -35 C>T SNP identified in CCD4(4B) promoter was found to be predictive for CCD4(4B) expression, and carotenoid content in fruits of a diverse germplasm collection, which included different octoploid Fragaria species. Taken together, these results provide important genetic insights into the natural variation of carotenoid content in strawberry. The High-Resolution Melting (HRM) DNA test here developed offers a fast and reliable method to predict high fruit carotenoid content, representing a useful tool for breeding projects aiming to enhance the nutritional value of this crop.

plant biology↗

bioRxiv2023

Strawberry phenotypic plasticity in flowering time is driven by interaction between genetic loci and temperature

The flowering time, which determines when the fruits or seeds can be harvested, is known to be sensitive to plasticity, i.e. the ability of a genotype to display different phenotypes in response to environmental variations. In the context of climate change, strawberry breeding can take advantage of phenotypic plasticity to create high-performing varieties adapted either to local conditions or to a wide range of climates. To decipher how the environment affects the genetic architecture of flowering time in cultivated strawberry (Fragaria xananassa) and modify its QTL effects, we used a bi-parental segregating population grown for two years at widely divergent latitudes (5 European countries) and combined climatic variables with genomic data (Affymetrix(R) SNP array). We detected 10 unique flowering time QTL and demonstrated that temperature modulates the effect of plasticity-related QTL. We propose candidate genes for the three main plasticity QTL, including FaTFL1 which is the most relevant candidate in the interval of the major temperature-sensitive QTL (6D_M). We further designed and validated a genetic marker for the 6D_M QTL which offers great potential for breeding programs, for example for selecting of early-flowering strawberry varieties well adapted to different environmental conditions. HighlightsA GXE study of a segregating strawberry population in Europe showed that temperature is the main driver of flowering time plasticity. A genetic marker was designed for the main QTL.

genetics↗

bioRxiv2021

Natural variation in the control of flowering and shoot architecture in diploid Fragaria species

In perennial fruit and berry crops of the Rosaceae family, flower initiation occurs in late summer or autumn after downregulation of a strong repressor TERMINAL FLOWER1 (TFL1) and flowering and fruiting takes place the following growing season. Rosaceous fruit trees typically form two types of axillary shoots, short flower-bearing shoots called spurs and long shoots that are respectively analogous to branch crowns and stolons in strawberry. However, regulation of flowering and shoot architecture differs between species and environmental and endogenous controlling mechanisms have just started to emerge. In woodland strawberry (Fragaria vesca L.), long days maintain vegetative meristems and promote stolon formation by activating TFL1 and GIBBERELLIN 20-OXIDASE4 (GA20ox4), respectively, while silencing of these factors by short days and cool temperatures induces flowering and branch crown formation. We characterized flowering responses of 14 accessions of seven diploid Fragaria species native to diverse habitats in the northern hemisphere, and selected two species with contrasting environmental responses, F. bucharica Losinsk. and F. nilgerrensis Schlecht. ex J. Gay for detailed studies together with F. vesca. Similar to F. vesca, F. bucharica was induced to flower in short days at 18{degrees}C and regardless of photoperiod at 11{degrees}C after silencing of TFL1. F. nilgerrensis maintained higher TFL1 expression level and likely required cooler temperatures or longer exposure to inductive treatments to flower. We also found that high expression of GA20ox4 was associated with stolon formation in all three species, and its downregulation by short days and cool temperature caused branch crown formation in F. vesca and F. nilgerrensis, although the latter did not flower. F. bucharica, in contrast, rarely formed branch crowns, regardless of flowering or GA20ox4 expression level. Our findings highlighted diploid Fragaria species as a rich source of genetic variation controlling flowering and plant architecture, with potential applications in breeding of Rosaceous crops.

plant biology↗

bioRxiv2020

Allelic Variation of MYB10 is the Major Force Controlling Natural Variation of Skin and Flesh Color in Strawberry (Fragaria spp.) fruit

Anthocyanins are the principal color-producing compounds synthesized in developing fruits of strawberry (Fragaria spp.). Substantial natural variation in color have been observed in fruits of diploid and octoploid accessions, resulting from distinct accumulation and distribution of anthocyanins in fruits. Anthocyanin biosynthesis is controlled by a clade of R2R3 MYB transcription factors, among which MYB10 has been shown as the main activator in strawberry fruit. Here, we show that MYB10 mutations cause most of the anthocyanin variation observed in diploid woodland strawberry (F. vesca) and octoploid cultivated strawberry (F. xananassa). Using a mapping-by-sequencing approach, we identified a gypsy-transposon insertion in MYB10 that truncates the protein and knocks out anthocyanin biosynthesis in a white-fruited F. vesca ecotype. Two additional loss-of-function MYB10 mutations were identified among geographically diverse white-fruited F. vesca ecotypes. Genetic and transcriptomic analyses in octoploid Fragaria spp. revealed that FaMYB10-2, one of three MYB10 homoeologs identified, residing in the F. iinumae-derived subgenome, regulates the biosynthesis of anthocyanins in developing fruit. Furthermore, independent mutations in MYB10-2 are the underlying cause of natural variation in fruit skin and flesh color in octoploid strawberry. We identified a CACTA-like transposon (FaEnSpm-2) insertion in the MYB10-2 promoter of red-fleshed accessions that was associated with enhanced expression and anthocyanin accumulation. Our findings suggest that putative cis regulatory elements provided by FaEnSpm-2 are required for high and ectopic MYB10-2 expression and induction of anthocyanin biosynthesis in fruit flesh. We developed MYB10-2 (sub-genome) specific DNA markers for marker-assisted selection that accurately predicted anthocyanin phenotypes in octoploid segregating populations.

plant biology↗