Biology subjects

Kleine, T.

Publications and source records attributed to Kleine, T..

3 recordsLinked to original sources

bioRxiv2023

Arabidopsis thaliana BBX14 is a target of GLK1 and involved in high-light acclimation, photomorphogenesis and GUN-type retrograde signaling

Development of photosynthetically competent seedlings requires both light and retrograde biogenic signaling pathways. The transcription factor GLK1 functions at the interface between these pathways, and receives input from the biogenic-signaling integrator GUN1. BBX14 was previously identified, together with GLK1, in a core module that mediates the response to high light levels and biogenic signaling. To gain insight into the function of BBX14, we generated BBX14 overexpressors and CRISPR/Cas-mediated bbx14 mutant plants, conducted high-light, RT-qPCR and ChIP-Seq experiments, measured photosynthetic parameters, chlorophyll contents and growth rates, and analyzed alterations in transcriptomics. We found that, although overexpression of BBX14 is deleterious under normal growth conditions, BBX14 is needed to acclimate plants to high light stress. BBX14 is a direct target of GLK1, and RNA-Seq analysis suggests that BBX14 is involved in the circadian clock. Knockout of BBX14 results in a long-hypocotyl phenotype that depends on a retrograde signal, and BBX14 expression during biogenic signaling requires GUN1. Finally, we clarify the role of BBX14 in GUN-type biogenic signaling. We conclude that BBX14 is an integrator of photomorphogenetic and biogenic signals, and suggest that BBX14 is a nuclear target of retrograde signals downstream of the GUN1/GLK1 module.

plant biology↗

bioRxiv2022

Response of the organellar and nuclear (post)transcriptomes of Arabidopsis to drought stress

Plants have evolved sophisticated mechanisms to cope with drought, which involve massive changes in nuclear gene expression. However, little is known about the roles of post-transcriptional processing of nuclear or organellar transcripts and how meaningful these changes are. To address these issues, we used long non-coding RNA-sequencing to monitor (post)transcriptional changes during different times of drought exposure in Arabidopsis Col-0 and a mutant (protein phosphatase 7-like, pp7l), from which we demonstrated that it can survive long periods of drought stress. The changes detected in the pp7l mutant were marginal, while in the wild type chloroplast transcript levels were globally reduced, editing efficiency dropped, but splicing was not affected. Mitochondrial transcripts were slightly elevated, while editing and splicing were unchanged. Also, transcriptional activation of transposable elements played only a minor role. Conversely, alternative splicing (AS) affected nearly 2,000 genes (11% of expressed nuclear genes). Of these, 25% underwent isoform switching, and 15% were regulated solely at the level of AS, representing transcripts that would have gone unnoticed in a microarray-based approach. Our data show that AS enhances proteome diversity to counteract drought stress and represent a valuable resource that will facilitate the development of new strategies to improve plant performance under drought. Moreover, altering the relative contributions of spliced isoforms might enhance drought resistance. For instance, our data imply that accumulation of a non-functional FLM (FLOWERING LOCUS M) isoform - and not the ratio of functional isoforms as suggested for temperature responses - accounts for the early-flowering phenotype under drought conditions.

plant biology↗

bioRxiv2021

The RNA-binding protein RBP45D of Arabidopis plays a role in epigenetic control of flowering time and DCL3-independent RNA-directed DNA methylation

RNA-directed DNA methylation (RdDM) helps to defend plants against invasive nucleic acids. In the canonical form of RdDM, 24-nt small interfering RNAs (siRNAs) are produced by DICER-LIKE 3 (DCL3). Here, we describe the Arabidopsis thaliana prors1 (LUC) transgenic system, in which transcriptional gene silencing (TGS) is independent of DLC3. A forward genetics screen performed with this system identified both known components of RdDM, and the RNA-binding protein RBP45D. RBP45D promotes DNA methylation, and its loss delays flowering, especially at high temperature, presumably mediated by elevated FLC levels. RBP45D is localized to the nucleus, where it is associated with snRNAs and snoRNAs. RBP45D maintains siRNA production originating from the LUC transgene, but does not alter mRNA levels or affect processing of transcripts of known RdDM genes. We suggest that RBPD45 facilitates DCL3-independent siRNA production by stabilising either the precursor RNA or the - as yet unidentified - slicer protein.

plant biology↗