Biology subjects

Wenkel, S.

Publications and source records attributed to Wenkel, S..

9 recordsLinked to original sources

bioRxiv2025

Antagonistic and Synergistic Roles of Tomato AFP3 Isoforms in Hormonal Regulation and Development

The ABA INSENSITIVE5 BINDING PROTEIN (AFP) family plays a critical role in abscisic acid (ABA) signaling through interaction with the transcription factor ABI5, impacting seed germination and stress responses. Here, we characterize tomato AFP3, which produces two isoforms: a full-length protein and a shorter microProtein (sAFP3) containing only the C-terminal domain. Functional analyses reveal contrasting roles of these isoforms in development; while AFP3 overexpression accelerates shoot growth but impairs seed germination, both afp3 loss-of-function and sAFP3-expressing mutants (afp3-D) exhibit stunted growth and developmental defects. Transcriptome profiling highlights that AFP3 and sAFP3 differentially regulate hormone-related pathways, including salicylic acid, gibberellic acid, and jasmonic acid metabolism. Proteomic interaction studies demonstrate that AFP3 and sAFP3 physically interact, sharing partners involved in hormone signaling. Hormone quantification confirms that AFP3 modulates multiple phytohormones, with elevated ABA in afp3-D mutants and increased gibberellic acid, jasmonic acid, and salicylic acid in both afp3 and afp3-D mutant backgrounds. Moreover, AFP3 controls flower and fruit development, influencing yield and ripening. Together, these findings identify AFP3 as a key integrator of hormonal crosstalk that coordinates growth, development, and stress responses in tomato. The production of dual AFP3 isoforms through alternative transcription, combined with microProtein-mediated dominant-negative regulation, reveals a sophisticated mechanism for dynamically fine-tuning transcriptional networks. This versatile strategy underscores how plants--and potentially other organisms--achieve precise control over complex signaling pathways.

plant biology↗

bioRxiv2024

Impact of mutations in the HEADING DATE 1 gene on transcription and cell wall composition of rice

Plants utilize environmental information to modify their developmental trajectories for optimal survival and reproduction. Over a century ago, day length (photoperiod) was identified as a major factor influencing developmental transitions, particularly the shift from vegetative to reproductive growth. In rice, exposure to day lengths shorter than a critical threshold accelerates flowering, while longer days inhibit this process. This response is mediated by HEADING DATE 1 (Hd1), a zinc finger transcription factor that is central in the photoperiodic flowering network. Hd1 acts as a repressor of flowering under long days but functions as a promoter of flowering under short days. However, the transcriptional organization of this dual function is still not fully understood. In this study, we utilized RNA-Seq to analyze the transcriptome of hd1 mutants under both long and short day conditions. We identified genes involved in the phenylpropanoid pathway that are deregulated under long days in the mutant. Quantitative profiling of cell wall components and abiotic stress assays suggest that Hd1 is involved in processes considered unrelated to flowering control. This indicates that day length perception and responses are intertwined with physiological processes beyond flowering.

plant biology↗

bioRxiv2024

A frosty genetic screen unmasks a major regulatory role for SHORT VEGETATIVE PHASE of flowering in response to a cold snap

The control of flowering in plants is intricately governed by a combination of internal and environmental signals, with temperature playing a critical role. Thus, Arabidopsis thaliana plants display temperature-dependent variations in flowering time. As unexpected periods of cold temperatures can occur at any time, plants have evolved mechanisms to detect such cold snaps and to respond by delaying flowering. Plants are more tolerant to cold temperatures in the vegetative stage, while flowers are more sensitive and have reduced reproductive success due to damage to floral structures and gametes. At the molecular level, delayed flowering can be caused by repressing the FLOWERING LOCUS T (FT) gene, and several MADS box transcription factors have been shown to repress FT expression in response to cold and in this way prevent flowering. Here, we employed a forward genetic screen aimed at understanding the effect of a cold snap on the transition to flowering. We germinated a population of A. thaliana EMS M2 plants at 20{degrees}C and then gradually lowered the temperature to 10{degrees}C and selected early flowering mutants. Using whole-genome sequencing, we identified seven mutant alleles of the SHORT VEGETATIVE PHASE (SVP) gene. This finding establishes a central role for SVP in repressing flowering in response to a cold snap and provides novel alleles, several of which affect splice junctions. Our research thus presents valuable insights into the nuanced molecular mechanisms governing temperature-responsive flowering in Arabidopsis and sheds light on the dynamic interplay between SVP and environmental cues.

plant biology↗

bioRxiv2024

A shade-responsive microProtein in the Arabidopsis ATHB2 gene regulates elongation growth and root development

Shade triggers widespread changes in transcript isoform production in Arabidopsis thaliana. Using 5' PEAT sequencing, we identified 377 candidate microprotein-encoding transcripts arising from alternative transcription start sites, including one located within the third exon of ATHB2, a class II HD-ZIP transcription factor central to shade avoidance. The encoded microprotein, ATHB2miP, lacks the DNA-binding homeodomain but retains the leucine zipper domain, through which it forms heterodimers with full-length ATHB2, inhibits its DNA-binding activity, and disrupts its localization to nuclear photobodies. Ectopic expression of ATHB2miP phenocopies loss of ATHB2, deregulating genes involved in auxin signaling, root development, and iron homeostasis. Complementation of the athb2 mutant with a construct carrying a silent mutation at the ATHB2miP start codon results in exaggerated hypocotyl elongation under both white light and shade, demonstrating that ATHB2miP is required to restrain excessive elongation growth. Immunoprecipitation mass spectrometry confirmed that this mutation redirects translation to alternative initiation sites, producing distinct proteoforms absent from wild-type plants. Additionally, ATHB2 suppresses iron uptake genes, and iron availability modulates shade growth responses in an ATHB2-dependent manner. Together, these findings establish ATHB2miP as a regulator of an ATHB2 feedback circuit that integrates light and nutritional signals to coordinate shoot elongation and root development.

plant biology↗

bioRxiv2023

Overexpression of tomato SlBBX16 and SlBBX17 impacts fruit development and GA biosynthesis

BBXs are B-Box zinc finger proteins that can act as transcription factors and regulators of protein complexes. Several BBX proteins play important roles in plant development. Two Arabidopsis thaliana microProteins belonging to the BBX family, named miP1a and miP1b, homotypically interact with and modulate the activity of other BBX proteins, including CONSTANS, which transcriptionally activates the florigen, FLOWERING LOCUS T. In tomato, the closest homologs of miP1a and miP1b are the microProteins SlBBX16 and SlBBX17. To deepen our understanding of the role of tomato microProteins in flowering, we constitutively expressed SlBBX16/17 in Arabidopsis and tomato and examined possible interacting partners. Overexpression of the two tomato microProteins in Arabidopsis caused a delay in the flowering transition; however, the effect was weaker than that observed in Arabidopsis plants overexpressing the native miP1a/b. In tomato, overexpression of SlBBX17 prolonged the flowering period; this effect was accompanied by downregulation of the flowering inhibitors Self Pruning (SP) and SP5G. SlBBX16 and SlBBX17 are able to hetero-oligomerize with TCMP-2, a cystine-knot peptide involved in flowering pattern and fruit development in tomato. Increasing the expression of both tomato microProteins also caused alterations in fruit development: overexpression of SlBBX17 resulted in a diminished number and size of ripe fruits as compared to WT plants, while overexpression of SlBBX16 caused delayed fruit production up to the breaker stage. These effects were associated with changes in the expression of genes regulating gibberellin content.

plant biology↗

bioRxiv2022

The m6A writer FIONA1 methylates the 3'UTR of FLC and controls flowering in Arabidopsis

Adenosine bases of RNA can be transiently modified by the deposition of a methyl-group to form N6-methyladenosine (m6A). This adenosine-methylation is an ancient process and the enzymes involved are evolutionary highly conserved. A genetic screen designed to identified suppressors of late flowering transgenic Arabidopsis plants overexpressing the miP1a microProtein yielded a new allele of the FIONA1 (FIO1) m6A-methyltransferase. To characterize the early flowering phenotype of fio1 mutant plants we employed an integrative approach of mRNA-seq, Nanopore direct RNA-sequencing and meRIP-seq to identify differentially expressed transcripts as well as differentially methylated mRNAs. We provide evidence that FIO1 is the elusive methylase responsible for the 3-end methylation of the FLOWERING LOCUS C (FLC) transcript. Furthermore, our genetic and biochemical data suggest that 3-methylation stabilizes FLC mRNAs and non-methylated FLC is a target for rapid degradation.

plant biology↗

bioRxiv2021

The genetic interaction of REVOLUTA and WRKY53 links plant development, senescence, and immune responses

In annual plants, tight coordination of successive developmental events is of primary importance to optimize performance under fluctuating environmental conditions. The recent finding of the genetic interaction of WRKY53, a key senescence-related gene with REVOLUTA, a master regulator of early leaf patterning, raises the question of how early and late developmental events are connected. Here, we investigated the developmental and metabolic consequences of an alteration of the REVOLUTA and WRKY53 gene expression, from seedling to fruiting. Our results show that REVOLUTA critically controls late developmental phases and reproduction while inversely WRKY53 determines vegetative growth at early developmental stages. We further show that these regulators of distinct developmental phases frequently, but not continuously, interact throughout ontogeny and demonstrated that their genetic interaction is mediated by the salicylic acid (SA). Moreover, we showed that REVOLUTA and WRKY53 are keys regulatory nodes of development and plant immunity thought their role in SA metabolic pathways, which also highlights the role of REV in pathogen defence. Together, our findings demonstrate how late and early developmental events are tightly intertwined by molecular hubs. These hubs interact with each other throughout ontogeny, and participate to the interplay between plant development and immunity.

plant biology↗

bioRxiv2018

Reversion of the photoperiod dependence of flowering in rice with synthetic Hd1-microProteins

Rice (Oryza sativa) is a facultative short-day plant that flowers very late when grown in non-inductive long day conditions. Photoperiod-dependent flowering in rice is regulated by heading date (Hd1) which acts as both an activator and repressor of flowering in a day length-dependent manner. In order to regulate flowering of rice in long days (LD), overexpression of a synthetic Hd1miP, which is capable of interacting with Hd1, was employed. Transgenic Hd1miP rice plants flowered significantly earlier when grown in LD compared to SD, showing that synthetic microProteins can be used to revert short-day plants to long-day plants. Yield analysis revealed that although the OX-Hd1miP grains are comparable to WT in terms of the size of the grains produced, OX-Hd1miP plants like hd1 knockout plants, are compromised in the number of grains produced and the grain maturity rate, suggesting an additional unrecognized role of Hd1 in grain maturity.

plant biology↗

bioRxiv2018

Dissection of the microProtein miP1 floral repressor complex in Arabidopsis

MicroProteins have emerged as potent regulators of transcription factor activity. Here we use a combination of forward genetics and proteomics to dissect the miP1a/b microProtein complex that acts to delay the floral transition in Arabidopsis. The microProteins miP1a and miP1b can bridge an interaction between the flowering promoting factor CONSTANS (CO) and the TOPLESS (TPL) co-repressor protein to represses flowering. We find that the JUMONJI14 (JMJ14) histone demethylase is part of this repressor complex that can initiate chromatin changes in FLOWERING LOCUS T (FT) gene, the direct target of CO. Plants with mutations in JMJ14 exhibit an early flowering phenotype that is largely dependent on the activity of CO, supporting a role for CO in this repressive complex. When mis-expressed at the shoot apex, CO can induce early flowering only in the jmj14 background. Our results indicate that the repressor acts in the shoot apical meristem to keep it in an undifferentiated state until the leaf-derived florigen signal induces the conversion into a floral meristem.

plant biology↗