Biology subjects

Herrera-Ubaldo, H.

Publications and source records attributed to Herrera-Ubaldo, H..

4 recordsLinked to original sources

bioRxiv2025

The transcription factor NO TRANSMITTING TRACT / WIP2 regulates cytokinin homeostasis in Arabidopsis

NO TRANSMITTING TRACT / WIP2 (NTT/WIP2) is a zinc finger transcription factor that alters developmental programs in Arabidopsis when overexpressed. Loss of NTT function, alone or in combination with closely related genes, leads to developmental defects in gynoecia and roots, respectively. Its overexpression phenotype resembles the effects of cytokinin treatments, suggesting a potential connection to this hormonal pathway. To further investigate this connection, we conducted cytokinin content and response evaluations, and transcriptome analyses in an inducible NTT line. Alterations in cytokinin content and response, as evaluated with the TCSn::GFP line, were observed. In both cases, as in the global expression analyses, the observed changes were dependent on the tissue analyzed. Moreover, Y1H and transactivation assays suggested direct NTT binding to the IPT5, AHP6 and CKX7, regulatory regions. We propose that NTT, among other mechanisms, regulates development through the modulation of cytokinin homeostasis at different levels, including its local concentration. Since NTT is a target of AUXIN RESPONSE FACTOR 5 / MONOPTEROS, the results presented here indicate that NTT connects an auxin input to a change in cytokinin levels.

plant biology↗

bioRxiv2024

ESR2 orchestrates cytokinin dynamics leading to developmental reprogramming and green callus formation

Callus formation and shoot regeneration are natural plant abilities triggered by stress and damage. They are also key components of tissue culture, which for many species is crucial for gene editing, transformation, propagation, and other technologies, and their study provides valuable insights into plant development. The transcription factor ENHANCER OF SHOOT REGENERATION 2 (ESR2/DRNL/BOL/SOB) promotes green callus formation in roots and shoot regeneration when overactive, while the phythormone cytokinin plays a prominent role in both phenomena. Yet, the positive action of ESR2 on the cytokinin pathway had not been previously described. We explored the effects of ESR2 and found that cytokinin content and the expression of the cytokinin biosynthesis gene ISOPENTENYLTRANSFERASE 5 (IPT5) increase in plants where ESR2 activity is induced. ESR2 also regulates the cytokinin signaling repressor ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER 6 (AHP6), and surprisingly, the ESR2-stimulated green calli formation requires both IPT5 and AHP6. Therefore, ESR2 promotes both cytokinin biosynthesis and cytokinin signaling inhibition and requires a paradoxical combination of these two for green callus induction. This finding provides a foundation to better understand the processes involved in tissue reprogramming towards callus formation and the role of ESR2 in shoot regeneration and the development of new organs.

plant biology↗

bioRxiv2024

Characterisation of cuticle mechanical properties: analysing stiffness in layered living systems to understand surface buckling patterns

Development of a living organism is a highly regulated process during which biological materials undergo constant change. De novo material synthesis and changes in mechanical properties of materials are key for organ development; however, few studies have attempted to produce quantitative measurements of the mechanical properties of biological materials during growth. Such quantitative analysis is particularly challenging where the material is layered, as is the case for the plant cuticle on top of the plant epidermal cell wall. Here, we focus on Hibiscus trionum flower petals, where buckling of the cuticle forms ridges, producing an iridescent effect. This ridge formation is hypothesised to be due to mechanical instability, which directly depends upon the mechanical properties of the individual layers within the epidermal cells. We present measurements of the mechanical properties of the surface layers of petal epidermal cells through atomic force microscopy (AFM) and the uniaxial tensile tester for ultrathin films (TUTTUT), across growth stages. We found that the wavelength of the surface ridges was set at the ridge formation stage, and this wavelength was preserved during further petal development, most likely because of the plasticity of the material. Our findings suggest that temporal changes in biological material properties are key to understanding the development of biological surface patterns.

plant biology↗

bioRxiv2018

An interaction map of transcription factors controlling gynoecium development in Arabidopsis

Flowers are composed of different organs, whose identity is defined at the molecular by the combinatorial activity of transcription factors (TFs). MADS-box TFs interact forming complexes that have been schematized in the quartet model. The gynoecium is the female reproductive part in the flower, crucial for plant reproduction, and fruit and seed production. Once carpel identity is established, a gynoecium containing many tissues arises. Several TFs have been identified as regulators of gynoecium development, and some of these TFs form complexes. However, broad knowledge about the interactions among these TFs is still scarce. In this work, we used a systems biology approach to understand the formation of a complex reproductive unit as the gynoecium by mapping binary interactions between well-characterized TFs. We analyzed over 3500 combinations and detected more than 200 protein-protein interactions (PPIs), resulting in a process specific interaction map. Topological analyses suggest hidden functions and novel roles for many TFs. Furthermore, a relationship between TFs involved in auxin and cytokinin signaling pathways and other TFs was observed. We analyzed the network by combining PPI data, expression and genetic data, allowing us to dissect it into several dynamic spatio-temporal sub-networks related to gynoecium development subprocesses.

plant biology↗