Biology subjects

Dhondt, S.

Publications and source records attributed to Dhondt, S..

4 recordsLinked to original sources

bioRxiv2024

High-throughput phenotyping reveals multiple drought responses of wild and cultivated Phaseolinae beans

Crop production worldwide is increasingly affected by drought stress. Although drought tolerance of a plant may be achieved through morphological, structural, physiological, cellular, and molecular adaptations, most studies remain limited to quantifying the effect of drought on biomass yield. Using a high-throughput phenotypic imaging system, we evaluated the drought tolerance of 151 bean accessions (Phaseolinae; Fabaceae) by quantifying five different traits simultaneously: biomass, water use efficiency, relative water content, chlorophyll content, and root/shoot ratio. Since crop wild relatives are important resources for breeding programmes, both wild and cultivated accessions were analyzed, the majority never evaluated for drought tolerance before. We demonstrate that the five traits are affected very differently by drought in the studied accessions, although a cluster analysis grouped the accessions into five distinct clusters with similar responses. We correlated the results for each accession to local climate variables at their original collection sites. Except for the root/shoot ratio, the results of all indicators were related to precipitation data, confirming that drought tolerant accessions grow in arid environments. This broader knowledge on the complex responses of plants to drought stress may prove an invaluable resource for future crop production. HighlightThis study presents an innovative approach for the fast evaluation of different drought tolerance traits of legumes. Multiple responses to drought were observed in the economically important Phaseolinae beans.

plant biology↗

bioRxiv2021

Gametogenesis in the green seaweed Ulva mutabilis coincides with massive transcriptional restructuring

The molecular mechanism underlying sexual reproduction in land plants is well understood in model plants and is a target for crop improvement. However, unlike land plants, the genetic basis involved in triggering reproduction and gamete formation remains elusive in most seaweeds, which are increasingly viewed as an alternative source of functional food and feedstock for energy applications. Here, gametogenesis of Ulva mutabilis, a model organism for green seaweeds, is studied. We analyze transcriptome dynamics at different time points during gametogenesis following induction of reproduction by fragmentation and removal of sporulation inhibitors. Analyses demonstrate that 45% of the genes in the genome are differentially expressed during gametogenesis. We identified several transcription factors that potentially play a key role in the early gametogenesis of Ulva given the function of their homologs in higher plants and microalgae. In particular, the detailed expression pattern of an evolutionary conserved transcription factor containing an RWP-RK domain suggests a key role during Ulva gametogenesis. The identification of putative master regulators of gametogenesis provides a starting point for further functional characterization. HighlightTranscriptomic analyses of gametogenesis in the green seaweed Ulva highlight the importance of a conserved RWP-RK transcription factor in induction of sexual reproduction.

plant biology↗

bioRxiv2020

Nighttime gibberellin biosynthesis is influenced by fluctuating environmental conditions and contributes to growth adjustments of Arabidopsis leaves.

Optimal plant growth performance requires that the action of growth signals, such as gibberellins (GA), are coordinated with the availability of photo-assimilates. Here, we studied the links between gibberellin biosynthesis and carbon availability, and the subsequent effects on growth. The results presented here show that carbon availability, light and dark cues, and the clock ensure the timing and magnitude of gibberellin biosynthesis and that disruption of these mechanisms results in reduced gibberellin levels and expression of downstream genes. Carbon dependent nighttime induction of GIBBERELLIN 3-BETA-DIOXYGENASE 1 (GA3ox1) was severely hampered when preceded by a day of lowered light availability, leading specifically to reduced bioactive GA4 levels, and coinciding with a decline in leaf expansion rate during the night. We attribute this decline in leaf expansion mostly to reduced photo-assimilates. However, plants where gibberellin limitation was alleviated had significantly improved expansion demonstrating the relevance of gibberellins in growth control under varying carbon availability. Carbon dependent expression of upstream gibberellin biosynthesis genes (KAURENE SYNTHASE, KS and GIBBERELLIN 20 OXIDASE 1, GA20ox1) was not translated into metabolite changes within this short timeframe. We propose a model where the extent of nighttime biosynthesis of bioactive GA4 by GA3ox1 is determined by starch, as the nighttime carbon source, and so provides day-to-day adjustment of gibberellin responses.

plant biology↗

bioRxiv2019

Population structure and geographically structured reproductive strategies of the haplodiplontic seaweed Dictyota dichotoma

Both mating system variation and the propensity of many seaweeds to reproduce both sexually and asexually, leave a strong imprint in the genetic structure of species. In this respect, we study the population genetic structure of Dictyota dichotoma, a common haplodiplont brown subtidal seaweed. This benthic species is widespread in the NE-Atlantic, from the Canary Islands and Mediterranean Sea to southern Norway, but lately populations have been reported from Argentina and South Africa. Phenology and reproduction of D. dichotoma was monitored year-round in four populations to investigate how the species has adapted to the steep thermal gradient in southern and northern ranges of its distribution. Thirteen microsatellites are developed in order to assess patterns of population diversity and structure across the biogeographic range, as shaped by past and present processes. Last, we assess the genetic structure of South African and South American populations and their relationship to the northern hemisphere populations.\n\nThroughout its range, D. dichotoma shows a varying reproductive effort, with sexual reproduction being more abundant in the northern range. In contrast, the Mediterranean populations show a clear sporophyte dominance, suggesting that sexual reproduction is not the prime mode of reproduction, and indicating that the species potentially resorts to other modes of propagation as for instance fragmentation or apospory.\n\nGenetic diversity is highest in the southern population decreasing gradually northward, indicative for a recolonization pattern after the demise of the last glacial maximum where these areas served as glacial refugia. European mainland populations show an isolation by distance pattern, while the population in the Canary Islands has its own genetic identity, being significantly diverged from the mainland population. Populations in South Africa and Argentina are seemingly introduced from mainland Europe, but no conclusion can be made on the exact timing of these introductions.

ecology↗