Biology subjects

Dirlewanger, E.

Publications and source records attributed to Dirlewanger, E..

3 recordsLinked to original sources

bioRxiv2018

Hormonal balance finely tunes dormancy status in sweet cherry flower buds

In temperate trees, optimal timing and quality of flowering directly depend on adequate winter dormancy progression, regulated by a combination of chilling and warm temperatures. Physiological, genetic and functional genomic studies have shown that hormones play a key role in bud dormancy establishment, maintenance and release. We combined physiological, transcriptional analyses, quantification of abscisic acid (ABA) and gibberellins (GAs), and modelling to further investigate how these signaling pathways are associated with dormancy progression in the flower buds of two sweet cherry cultivars. Our results demonstrated that GA-associated pathways have distinct functions and may be differentially related with dormancy. In addition, ABA levels rise at the onset of dormancy, associated with enhanced expression of ABA biosynthesis PavNCED genes, and decreased prior to dormancy release. Following the observations that ABA levels are correlated with dormancy depth, we identified PavUG71B6, a sweet cherry UDP-GLYCOSYLTRANSFERASE gene that up-regulates active catabolism of ABA to ABA-GE and may be associated with low ABA content in the early cultivar. Subsequently, we modelled ABA content and dormancy behavior in three cultivars based on the expression of a small set of genes regulating ABA levels. These results strongly suggest the central role of ABA pathway in the control of dormancy progression and open up new perspectives for the development of molecular-based phenological modelling.

plant biology↗

bioRxiv2018

Chromatin immunoprecipitation-sequencing and RNA-sequencing for complex and low-abundance tree buds

Chromatin immunoprecipitation-sequencing (ChIP-seq) is a robust technique to study interactions between proteins, such as histones or transcription factors, and DNA. This technique in combination with RNA-sequencing (RNA-seq) is a powerful tool to better understand biological processes in eukaryotes. We developed a combined ChIP-seq and RNA-seq protocol for tree buds (Prunus avium L., Prunus persica L Batch, Malus x domestica Borkh.) that has also been successfully tested on Arabidopsis thaliana and Saccharomyces cerevisiae. Tree buds contain phenolic compounds that negatively interfere with ChIP and RNA extraction. In addition to solving this problem, our protocol is optimised to work on small amounts of material. Furthermore, one of the advantages of this protocol is that samples for ChIP-seq are cross-linked after flash freezing, making it possible to work on trees growing in the field and to perform ChIP-seq and RNA-seq on the same starting material. Focusing on dormant buds in sweet cherry, we explored the link between expression level and H3K4me3 enrichment for all genes, including a strong correlation between H3K4me3 enrichment at the DORMANCY-ASSOCIATED MADS-box 5 (PavDAM5) loci and its expression pattern. This protocol will allow analysis of chromatin and transcriptomic dynamics in tree buds, notably during its development and response to the environment.

plant biology↗

bioRxiv2018

Productivity definition of the chilling requirement reveals underestimation of the impact of climate change on winter chill accumulation

Evaluation of chilling requirements (CR) of cultivars of temperate fruit trees provides key information to assess regional suitability, according to winter chill, for both industry expansion and ongoing profitability as climate change continues. Traditional methods for calculating CR use climate controlled chambers and define CR using a fixed budburst percentage, usually close to 50% (CR-50%), without considering the productivity level associated to this percentage. This CR-50% definition may underestimate the real CR of tree crops for optimal productivity. This underestimation is particularly important to consider as winter chill accumulation is declining in many regions due to climate change. In this work we used sweet cherry to analyse the traditional method for calculating CR in many Rosaceae species (CR-50%) and compared the results with more a restrictive, productivity focused method, with CR defined with a 90% bud break level (90%, CRm-90%) close to the optimal budburst which assures productivity. Climate projections of winter chill suitability across Europe using CR-50% and CRm-90% were calculated. Regional suitability landscape was highly dependent on the method used to define CR and differences were found for a wide area of the European geography, both cold and mild winter areas. Our results suggest a need to use an optimal budburst level for the assessment of CR for sweet cherry. The use of traditional methods to determine CR can result in an underestimation of productivity CR with negative consequences for the fruit industry, particularly as climate change advances.

plant biology↗