Biology subjects

Musialak-Lange, M.

Publications and source records attributed to Musialak-Lange, M..

4 recordsLinked to original sources

bioRxiv2024

FLOWERING LOCUS C integrates carbon and nitrogen signaling for the proper timing of flowering in Arabidopsis

The timing of flowering in plants is modulated by both carbon (C) and nitrogen (N) signaling pathways. In a previous study, we established a pivotal role of the sucrose-signaling trehalose 6-phosphate pathway in regulating flowering under N-limited short-day conditions. In this work, we expand on our finding that wild-type plants grown under N-limited short days require an active trehalose 6-phosphate pathway to be able to flower. Both wild-type plants grown under N-limited conditions and knock-down plants of TREHALOSE PHOSPHATE SYNTHASE1 induce FLOWERING LOCUS C expression, a well-known floral repressor associated with the vernalization response. When exposed to an extended period of cold, a mutant of FLOWERING LOCUS C fails to respond to N availability, and flowers at the same time under N-limited and full-nutrition conditions. Our data suggest that SUCROSE NON-FERMENTING 1 RELATED KINASE 1-dependent trehalose 6-phosphate-mediated C signaling and a novel mechanism downstream of N signaling likely involving NIN-LIKE PROTEIN 7 impact the expression of FLOWERING LOCUS C. Collectively, our data underscore the existence of a multi-factor regulatory system in which both C and N signaling pathways jointly govern the regulation of flowering in plants.

plant biology↗

bioRxiv2024

The Regulatory-Associated Protein of the Target of Rapamycin Complex, RAPTOR1B, interconnects with the photoperiod pathway to promote flowering in Arabidopsis

Transition from vegetative to reproductive growth (floral transition) is a strictly regulated energy-demanding process. In Arabidopsis, light perception coupled with internal circadian rhythms allows sensing changes in the duration of the light period (photoperiod) to accelerate flowering under long days (LD) in spring. This photoperiod-mediated floral induction relies on the accumulation of CONSTANS (CO) at dusk, a transcription factor that upregulates FLOWERING LOCUS T (FT) in leaves. Subsequently, FT protein moves into the shoot apical meristem to trigger the floral transition. Light and circadian clock-related signals are known to control CO at the genetic and protein levels; however, less is known about how energy sensing regulates components of the photoperiod pathway to modulate flowering. Here, we found that RAPTOR, a component of the Target Of Rapamycin complex (TORC), contributes to the induction of specific flowering genes that are under CO control. While transcription of CO remains intact in raptor mutants, its protein levels are reduced at dusk compared to wild-type (Col-0). This is due to increased protein degradation. Remarkably, GIGANTEA (GI) protein levels, which contributes to CO stabilization at dusk, are likewise hampered in the mutant. We show that RAPTOR interacts with and co-localizes at the nucleus with GI, altering GI levels through an unknown posttranscriptional mechanism. Phenotypic and molecular analysis of genetic crosses placed RAPTOR upstream of CO and GI. Since TORC is an energy sensor, our work suggests that RAPTOR could convey energy status information into the photoperiod sensing mechanism to fine-tune flowering behavior. Significance statementFor annual plants, such as Arabidopsis, the correct timing of flowering in spring/summer is critical for reproductive success. Molecular mechanisms through which plants perceive and integrate day length with internal rhythms to accelerate flowering under long days are well described. However, little is known about the pathways sensing and conveying energy availability to the flowering programs. We found that RAPTOR, the regulatory unit of Target of Rapamycin complex (TORC), regulates CONSTANS post-transcriptionally through GIGANTEA. Both proteins are components of the photoperiod pathway of the flowering network and their miss-regulation in raptor mutants hampers the upregulation of genes promoting flowering. Our work suggests that the high energy available in long days is sensed and integrated into the photoperiod pathway by TORC.

plant biology↗

bioRxiv2021

Sugar Signaling Induces Dynamic Changes during Meristem Development in Arabidopsis

Aerial parts of plants originate from pluripotent stem cells in the shoot apical meristem. Their population is maintained via the maintenance regulators WUSCHEL and CLAVATA3 in a negative feed-back loop. Meristem size is dynamic and undergoes a more than 2-fold expansion upon the transition to reproductive growth. The mechanism controlling this doming is largely unknown, but coinciding increased trehalose 6-phosphate and changed meristem size in overexpressing or knockdown lines of TREHALOSE PHOSPHATE SYNTHASE1 suggest a participation of sugar signaling. Here we show that TREHALOSE PHOSPHATE PHOSPHATASEJ is directly regulated by WUSCHEL. Plants with reduced levels of TREHALOSE PHOSPHATE PHOSPHATASEJ in the outer meristem layer are flowering early and its reduction in the late flowering clavata3 mutant, restores wild-type flowering. This is caused by a reduction of mature miR156 and increased expression of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE genes. We demonstrate that these are important for age pathway-induced flowering, in a negative feed-back loop with WUSCHEL downstream of the trehalose 6-phosphate pathway. In summary, our findings demonstrate a dynamic feed-back regulation between central maintenance and flowering time regulators with sugar signaling. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=169 SRC="FIGDIR/small/439483v2_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@988d6eorg.highwire.dtl.DTLVardef@16d469borg.highwire.dtl.DTLVardef@1366ce5org.highwire.dtl.DTLVardef@2753f0_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOSynopsis:C_FLOATNO Schematic illustration of dynamic feedback-regulations between sugar signaling, meristem maintenance and the age pathway of the flowering network in the transition SAM as compared to the vegetative SAM.During vegetative growth SAM maintenance is controlled by spatially separated WUS and CLV3 expression in a negative feedback-loop. At floral transition increased activity of the T6P pathway in the SAM uncouples this regulation. This results in an unreported special relocation of WUS expression and involves a transient negative feedback-loop between WUS and SPL4. C_FIG

plant biology↗

bioRxiv2017

AtRsgA from Arabidopsis thaliana controls maturation of the small subunit of the chloroplast ribosome

SummaryPlastid ribosomes are very similar in structure and function to ribosomes of their bacterial ancestors. Since ribosome biogenesis is not thermodynamically favourable at biological conditions, it requires activity of many assembly factors. Here, we have characterized a homolog of bacterial rsgA in Arabidopsis thaliana and show that it can complement the bacterial homolog. Functional characterization of a strong mutant in Arabidopsis revealed that the protein is essential for plant viability, while a weak mutant produced dwarf, chlorotic plants that incorporated immature pre-16S ribosomal RNA into translating ribosomes. Physiological analysis of the mutant plants revealed smaller, but more numerous chloroplasts in the mesophyll cells, reduction of chlorophyll a and b, depletion of proplastids from the rib meristem and decreased photosynthetic electron transport rate and efficiency. Comparative RNA-sequencing and proteomic analysis of the weak mutant and wild-type plants revealed that various biotic stress-related, transcriptional regulation and post-transcriptional modification pathways were repressed in the mutant. Intriguingly, while nuclear- and chloroplast-encoded photosynthesis-related proteins were less abundant in the mutant, the corresponding transcripts were upregulated, suggesting an elaborate compensatory mechanism, potentially via differentially active retrograde signalling pathways. To conclude, this study reveals a new chloroplast ribosome assembly factor and outlines the transcriptomic and proteomic responses of the compensatory mechanism activated during decreased chloroplast function.\n\nSignificance statementAtRsgA is an assembly factor necessary for maturation of the small subunit of the chloroplast ribosome. Depletion of AtRsgA leads to dwarfed, chlorotic plants and smaller, but more numerous chloroplasts. Large-scale transcriptomic and proteomic analysis revealed that chloroplast-encoded and - targeted proteins were less abundant, while the corresponding transcripts were upregulated in the mutant. We analyse the transcriptional responses of several retrograde signalling pathways to suggest a mechanism underlying this compensatory response.

molecular biology↗