Biology subjects

Bechtold, U.

Publications and source records attributed to Bechtold, U..

6 recordsLinked to original sources

bioRxiv2025

MYB59 is linked to natural variation of water use associated with warmer temperatures in Arabidopsis thaliana

Water-use contributes significantly to plant growth and productivity, yet the extent to which variation in water-use is a function of adaptive differentiation is unknown. Here, we studied natural variation of water use in Arabidopsis thaliana to understand how climatic history impacts water use strategies. We performed a survey of vegetative water use (VWU) and life-history traits across A. thaliana ecotypes in controlled and outdoor settings. Performance of select ecotypes in controlled experiments was reflective of performance in outdoor conditions. Through trait-climate and genome-wide association (GWAS) analyses, we tested for signals of environmental adaption in water use. Ecotypes from warmer environments were noted in displaying enhanced water use, independent of precipitation. GWAS identified MYB59 as a determiner of VWU. Functionally significant MYB59 SNPs showed associations with temperature, but not precipitation, and myb59 mutants demonstrated reduced water use under high temperatures. Our study suggests intraspecific variation in water-use can be explained in part by climatic history, where temperature is the most significant driver. MYB59 appears involved in this association and holds promise for study in crops.

plant biology↗

bioRxiv2024

Gene body methylation buffers noise in gene expression in plants

Non-genetic variability in gene expression is an inevitable consequence of stochastic nature of processes driving transcription and translation. Largely thought to be deleterious to cell fitness, it is not uniform across the transcriptome. This implies the existence of (molecular) determinants affecting the degree of gene expression variability, although this remain poorly understood in multicellular systems. In this study, we found a link between gene body methylation and noise in gene expression in Arabidopsis thaliana. More specifically, genes with high levels of noise show low levels of gene body methylation, while genes with lower level of noise in gene expression show higher level of gene body methylation. Most importantly, loss of CpG methylation in gene bodies lead to a significant number of genes displaying higher noise in gene expression. This could be compensated by low but significant gain of non-CpG methylation at promoters of certain genes. Overall, our results show that gene body methylation has a functional role and specifically controls the noise in gene expression for a large number of genes.

molecular biology↗

bioRxiv2024

DNA methylation contributes to plant acclimation to naturally fluctuating light

Plants in the natural environment experience continuous dynamic changes in light intensity. We have limited understanding on how plants adapt to such variable conditions. Here, we exposed Arabidopsis thaliana plants to naturally fluctuating light regimes alongside traditional square light regimes such as those often found in control environment growth chambers. The physiological response was highly consistent across experiments, indicating the involvement of an epigenetic mechanism, leading us to investigated differences in DNA methylation. Our results identified a large number of alterations in DNA methylation patterns between fluctuating light acclimated plants, and square light acclimated plants, demonstrating natural fluctuations in light impacts the plant epigenetic mechanisms. Most importantly, there are more differences in DNA methylation patterns between different light pattern regimes than between different light intensities. These differences in DNA methylation were accompanied by significant changes in gene expression, some of which correlated with altered DNA methylation. Interestingly, several transposable elements which displayed differential methylation were found to be differentially expressed between light regimes. Our data suggests DNA methylation plays a role in acclimation to natural light which may directly regulate gene expression and impact transposable element activation.

genomics↗

bioRxiv2024

ROS responsive Aux/IAA multimerization modulates auxin responses

Reactive oxygen species (ROS) function as key signals in plants to enable adaptation to environmental stresses. Plant roots respond to transient water stress by temporarily ceasing branching using the acclimative response xerobranching1. In this study, we report that a rapid ROS burst regulates Xerobranching by inducing multimerization of auxin repressor protein IAA3/SHY2. Mutations in specific cysteine residues in IAA3/SHY2 disrupt redox-mediated multimerization and interaction with co-repressor TPL, but not with auxin response partner ARF7 and auxin receptor TIR1. ROS-mediated oligomerization of IAA3/SHY2 is required for efficient ARF mediated target gene repression during Xerobranching and lateral root emergence. We demonstrate that AUX/IAA proteins vary in their redox mediated multimerization, revealing a new auxin response regulatory mechanism that directly connects ROS sensing to auxin signalling. Our study reveals how ROS, auxin and water stress intersect to shape acclimative responses in plant roots and maintain their phenotypic plasticity.

plant biology↗

bioRxiv2020

Time series transcriptomics reveals a BBX32-directed control of dynamic acclimation to high light in mature Arabidopsis leaves

The photosynthetic capacity of mature leaves increases after several days exposure to constant or intermittent episodes of high light (HL) and is manifested primarily as changes in chloroplast physiology. This is termed dynamic acclimation but how it is initiated and controlled is unknown. From fully expanded Arabidopsis leaves, we determined HL-dependent changes in transcript abundance of 3844 genes in a 0-6h time-series transcriptomics experiment. It was hypothesised that among such genes were those that contribute to the initiation of dynamic acclimation. By focussing on HL differentially expressed transcription (co-)factor (TF) genes and applying dynamic statistical modelling to the temporal transcriptomics data, a gene regulatory network (GRN) of 47 predominantly photoreceptor-regulated (co)-TF genes was inferred. The most connected gene in this network was B-BOX DOMAIN CONTAINING PROTEIN32 (BBX32). Plants over-expressing BBX32 were strongly impaired in dynamic acclimation and displayed perturbed expression of genes involved in its initiation. These observations led to demonstrating that as well as regulation of dynamic acclimation by BBX32, CRYPTOCHROME1, LONG HYPOCOTYL5, CONSTITUTIVELY PHOTOMORPHOGENIC1 and SUPPRESSOR OF PHYA-105 are also important regulators of this process. Additionally, the BBX32-centric GRN provides a view of the transcriptional control of dynamic acclimation distinct from other photoreceptor-regulated processes, such as seedling photomorphogenesis.

plant biology↗

bioRxiv2018

Non-functional and weak alleles of FRIGIDA and FLOWERING LOCUS C reduce lifetime water-use independent of leaf-level water-use-efficiency traits in Arabidopsis thaliana

Natural selection driven by water availability has resulted in considerable variation for traits associated with drought tolerance and leaf level water-use efficiency (WUE). In Arabidopsis, little is known about the variation of whole-plant water use (PWU) and whole-plant WUE (TE). To investigate the genetic basis of PWU, we developed a novel proxy trait by combining flowering time and rosette water use to estimate lifetime PWU. We validated its usefulness for large scale screening of mapping populations in a subset of ecotypes. This parameter subsequently facilitated the screening of water-use but also drought tolerance traits in a recombinant inbred line population derived from two Arabidopsis accessions with distinct water use strategies, namely C24 (low PWU) and Col-0 (high PWU). Subsequent quantitative trait loci (QTL) mapping and validation through near-isogenic lines identified two causal QTLs, which showed that a combination of weak and non-functional alleles of the FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) genes substantially reduced plant water-use without penalising reproductive performance. Drought tolerance traits, stomatal conductance, intrinsic water use efficiency ({delta}13C) and rosette water-use were independent of allelic variation at FRI and FLC, suggesting that flowering is critical in determining life-time plant water use, but not leaf-level traits.

plant biology↗