bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/716373

AtDAT1 is a key enzyme of D-amino acid stimulated ethylene production in Arabidopsis thaliana

Suarez, J.·Hener, C.·Lehnhardt, V.-A.·Hummel, S.·Stahl, M.·Kolukisaoglu, U.
View original source ↗Export metadata ↓

Abstract

D-enantiomers of proteinogenic amino acids (D-AAs) are found ubiquitously, but the knowledge about their metabolism and functions in plants is scarce. A long forgotten phenomenon in this regard is the D-AA-stimulated ethylene production in plants. As a starting point to investigate this effect the Arabidopsis accession Landsberg erecta (Ler) got into focus as it was found defective in metabolizing D-AAs. Combining genetics and molecular biology of T-DNA lines and natural variants together with biochemical and physiological approaches we could identify AtDAT1 as a major D-AA transaminase in Arabidopsis. Atdat1 loss-of-function mutants and Arabidopsis accessions with defective AtDAT1 alleles were not able to produce D-Ala, D-Glu and L-Met, the metabolites of D-Met, anymore. This result corroborates the biochemical characterization of AtDAT1, which showed highest activity using D-Met as substrate. Germination of seedlings in light and dark led to enhanced growth inhibition of atdat1 mutants on D-Met. Ethylene measurements revealed an enhanced D-AA stimulated ethylene production in these mutants. According to initial working models of this phenomenon D-Met is preferentially malonylated instead of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). This decrease of ACC degradation should then lead to the increase of ethylene production. We could observe in our studies a reciprocal relation of malonylated methionine and ACC upon D-Met application and even significantly more malonyl-methionine in atdat1 mutants. Unexpectedly, the malonyl-ACC levels did not differ between mutants and wild type in these experiments. With AtDAT1, the first central enzyme of plant D-AA metabolism was characterized biochemically and physiologically. The specific effects of D-Met on ACC metabolization, ethylene production and plant development of dat1 mutants unraveled the impact of AtDAT1 on these processes, but they are not in full accordance to previous working models. Instead, our results imply the influence of additional candidate factors or processes on D-AA-stimulated ethylene production which await to be uncovered.

Source connections

Explore related subjects

plant biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Suarez, J., Hener, C., Lehnhardt, V.-A., Hummel, S., Stahl, M., Kolukisaoglu, U.. 2019-07-26. AtDAT1 is a key enzyme of D-amino acid stimulated ethylene production in Arabidopsis thaliana. https://doi.org/10.1101/716373

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Growth, yield, and quality of hot pepper (Capsicum annuum L.) as affected by the combined application of liquid bio-slurry and NPS fertilizer rates in Kucha, Gamo zone, south Ethiopia

Hot pepper (Capsicum annuum L.) is a key cash and nutritional crop in Ethiopia, yet its productivity remains constrained by inadequate and imbalanced soil nutrient management. Therefore, the field experiment was conducted in Kucha woreda, Gamo Zone, South Ethiopia, during the 2024/25 cropping season to investigate the effect of liquid bio-slurry and NPS fertilizer rates on growth, yield and quality of hot pepper. The experiment consisted of 16 treatments arranged in a factorial combination of four liquid bio-slurry (LBS) rates (0, 20, 40, and 60 m3 ha-1) and four NPS fertilizer rates (0, 75, 150, and 225 kg ha-1) using a randomized complete block design with three replications. All experimental data were collected following standard agronomic procedures and subjected to analysis of variance using GenStat statistical software (18th edition). The results revealed that both the main and interaction effects of liquid bio-slurry and NPS significantly (p < 0.01) influenced phenological, growth, yield, and quality parameters. The combined application of 150 kg ha-1 NPS and 60 m3 ha-1 LBS produced the highest marketable dry fruit yield (2.94 t ha-1) and total dry fruit yield (3.16 t ha-1), representing a 129.69% yield advantage over the control (1.28 t ha-1) in the case of marketable dry fruit yield. The findings demonstrate that integrated nutrient management using combined LBS and NPS fertilizers significantly enhanced the productivity and quality of hot pepper. Therefore, the application of 150 kg ha-1 NPS combined with 60 m3 ha-1 liquid bio-slurry is recommended for improved hot pepper production for the study area and similar agro-ecological conditions.

plant biology↗
bioRxiv2026

Robust planar morphogenesis in leaf-like organs requires callose-dependent coordination of division and growth

Planar organs, such as leaves, are key developmental innovations underlying the evolutionary success of plants. In vascular plants, building a planar organ requires coordinating cell division and growth both within the organ plane and across multiple, mechanically distinct cell layers. Phyllids, the leaf-like organs of bryophytes, typically consist of a single cell layer and offer a minimal system to decouple in-plane growth coordination from inter-layer mechanics. Here, we investigate how robust planar morphogenesis is achieved in phyllids, using the moss Physcomitrium patens as a bryophyte model. We show that impaired cytokinesis, caused by the loss of a callose synthase gene, disrupts growth gradients, ultimately yielding smaller, non-planar organs of variable shape. Combining quantitative live imaging with computational modeling, we show that the severity of shape defects in mutants depends on the spatial distribution and developmental timing of local growth arrests. These findings reveal how callose-dependent coordination between cell division and in-plane growth prevents mechanical conflicts and maintains planarity in a monolayered plant organ.

plant biology↗
bioRxiv2026

Structural determinants underlie the essentiality of the m-type thioredoxin TrxA in Synechocystis

Thioredoxins are central regulators of thiol-based redox signaling in photosynthetic organisms, where multiple isoforms with partially overlapping functions coexist. Among them, TrxA is the cyanobacterial homolog of chloroplast m-type thioredoxins and the only thioredoxin known to be essential in cyanobacteria. However, it is unclear whether this essentiality is due to its high intracellular abundance or to its specific molecular properties. Here, we evaluated the ability of different thioredoxins to functionally replace TrxA and used TrxA/TrxB chimeras to identify the structural determinants underlying its functional specificity. Overexpression of TrxB, TrxQ or TrxC did not support complete segregation of a disrupted trxA locus, although the proteins accumulated to levels comparable to those of endogenous TrxA. Similarly, heterologous expression of NTRC did not rescue the phenotype associated with reduced TrxA levels. Comparative structural analysis revealed differences in surface electrostatics and structural features surrounding the catalytic site of TrxA compared with the other thioredoxins. Analysis of TrxB/TrxA chimeras showed that determinants required for functional complementation are primarily located within the C-terminal region of TrxA. Chimeric variants also differed in their ability to activate cyanobacterial FBP/SBPase and pea chloroplast FBPase in vitro, supporting a role for this region in target-specific interactions. Together, these results demonstrate that the essential function of TrxA cannot be explained by protein abundance alone and requires molecular determinants located primarily within its C-terminal region.

plant biology↗