Biology subjects

Bakan, B.

Publications and source records attributed to Bakan, B..

5 recordsLinked to original sources

bioRxiv2025

Role of the tomato MARS1/ROUGH gene encoding a LYSINE-SPECIFIC HISTONE DEMETHYLASE 1 in adventitious root and fruit skin formation

In contrast to animals, plants have a high regenerative capacity, and they can form new organs and even complete individuals from a few cells present in adult tissues, either in response to injury or to the alteration of their environment. In this study, we describe the isolation and characterization of the more adventitious roots1-1 (mars1-1) mutant, which exhibits enhanced regenerative potential upon wounding in tomato hypocotyl explants. Additionally, the mars1-1 fruits exhibited a rough surface due to the ectopic proliferation of subepidermal cells, which formed callus-like structures on the cuticle. The MARS1/ROUGH gene encodes a conserved lysine-specific histone demethylase, SlLSD1, which regulates a variety of processes in metazoans, including cell proliferation, stem cell pluripotency, and embryogenesis. Two CRISPR/Cas9 null alleles, mars1-2 and mars1-3, were generated and their pleiotropic phenotype was characterized. We found elevated levels of H3K4me1 in mars1/rough seedlings, which suggests that SlLSD1 is required for the demethylation of this histone mark. To ascertain the impact of altered epigenetic marks in the mars1/rough mutants on gene expression regulation, we conducted a transcriptome analysis using a variety of RNA-Seq studies on tomato hypocotyls. By employing specific bioinformatic workflows and leveraging on the resolution of directional RNA-Seq data, we have identified over several dozen distinct genomic regions that exhibit de novo expression in the mars1/rough mutants. One such region includes a novel B-type cyclin gene, which is upregulated in the mars1/rough mutants and may account for the observed phenotypes. Our findings indicate that SlLSD1 plays a role in the establishment and maintenance of silencing in specific genomic regions that are essential for tissue-specific reprogramming.

plant biology↗

bioRxiv2024

Targeting the tomato fruit cuticle by gene overexpression and editing with the fruit epidermis-preferential nsLTP promoter

The thick cuticle covering and embedding epidermal cells of tomato (Solanum lycopersicum) fruit, a model for cuticle studies, plays important roles in fruit protection and quality. To further our understanding of the influence of cuticle components on cuticle architecture and properties, the next step is to engineer cuticle composition. Ideally, to avoid indirect effects at whole-plant level, a fruit-and epidermis-specific promoter should be used. Here, to overexpress and edit target genes in tomato, we selected a non-specific Lipid Transfer Protein 2 promoter (pronsLTP) with preferential activity in fruit epidermis, as shown by NLS-GFP fluorescence analysis. Overexpression of SlMYB75 driven by pronsLTP induced anthocyanin accumulation specifically in the growing fruit epidermis, consistent with the cuticle deposition pattern. In keeping with changes in anthocyanins, the cuticle composition in flavonoids and phenolic acids was altered, as shown by Raman microspectroscopy, as were several cuticle properties. We then edited the carotenoid PSY1 gene with a pronsLTP-driven CRISPR/Cas9 system. Different PSY1 knock-out alleles were detected predominantly in fruit exocarp and mesocarp of color-impaired pronsLTP::Cas9-Psy1 mutants, and very little in the leaf. A mutant carrying a heritable knock-out mutation in both fruit and leaf was also detected, indicating that mutants obtained with pronsLTP may require screening before being studied. Altogether, our results indicate that pronsLTP2 can efficiently result in gene overexpression and editing in fruit epidermis. Implications of these findings are important for the functional analysis and genetic engineering of cuticle-related genes in tomato.

plant biology↗

bioRxiv2023

An ancient role for the CYP73 gene family in t-cinnamic acid 4-hydroxylation, phenylpropanoid biosynthesis and embryophyte development

The phenylpropanoid pathway is a plant metabolism intimately linked to the transition to terrestrial life. It produces phenolic compounds that play essential roles in stress mitigation and ecological interactions. The pathway also provides the building blocks for hydrophobic polymers that form apoplastic diffusion barriers and make up a significant fraction of the land plant biomass. Despite its significance in embryophytes (i.e., land plants), the origin and evolutionary history of the phenylpropanoid pathway remain poorly understood. In particular, little is known about the organization and function of the pathway in bryophytes, the non-vascular embryophytes. In this study, we conducted a multidisciplinary analysis of the CYP73 gene family that encodes t-cinnamic acid 4-hydroxylase (C4H), the first plant-specific enzyme in the pathway. Our results indicate that C4H activity originated with the emergence of the CYP73 gene family in an ancestor of land plants and was supported by an arginine residue that stabilizes its substrate in the active site. C4H deficiency in the moss Physcomitrium patens, the liverwort Marchantia polymorpha and the hornwort Anthoceros agrestis resulted in a shortage of phenylpropanoids and abnormal plant development. The latter could be rescued in the moss by the exogenous supply of p-coumaric acid, the product of C4H. Our findings establish the emergence of the CYP73 gene family as a foundational event for the development of the canonical plant phenylpropanoid pathway and underscores the deep-rooted conservation of the C4H enzyme function in embryophyte biology.

plant biology↗

bioRxiv2023

Cutin-Derived Oligomers Act as Damage-Associated Molecular Patterns in Arabidopsis thaliana

The cuticle constitutes the outermost defensive barrier of most land plants. It comprises a polymeric matrix - cutin, surrounded by soluble waxes. Moreover, the cuticle constitutes the first line of defense against pathogen invasion, while also protecting the plant from many abiotic stresses. Aliphatic monomers in cutin have been suggested to act as immune elicitors in plants. This study analyses the potential of tomato cutin oligomers to act as damage-associated molecular patterns (DAMPs) able to induce a rapid immune response in the model plant Arabidopsis. Cutin oligomeric mixtures led to Ca2+ influx and MAPK activation in Arabidopsis. Comparable responses were measured for cutin, which was also able to induce a reactive oxygen species (ROS) burst. Furthermore, treatment of Arabidopsis with cutin oligomers resulted in a unique transcriptional reprogramming profile, having many archetypal features of pattern-triggered immunity (PTI). Targeted spectroscopic and spectrometric analyses of the cutin oligomers suggest that the elicitors compounds consist mostly of two up to three 10,16-dihydroxyhexadecanoic acid monomers linked together through ester bonds. This study demonstrates that cutin breakdown products can act as DAMPs; a novel class of elicitors deserving further characterization.

plant biology↗

bioRxiv2022

Cuticle architecture and mechanical properties: a functional relationship delineated through correlated multimodal imaging

O_LICuticle are multifunctional hydrophobic biocomposites that protect aerial organs of plants. Along plant development, plant cuticle must accommodate different mechanical constraints combining extensibility and stiffness, the corresponding structure-function relationships are unknown. Recent data showed a fine architectural tuning of the cuticle architecture and the corresponding chemical clusters along fruit development which raise the question of their impact on the mechanical properties of the cuticle. C_LIO_LIWe investigated the in-depth nanomechanical properties of tomato fruit cuticle from early development to ripening, in relation to chemical and structural heterogeneities by developing a correlative multimodal imaging approach. C_LIO_LIUnprecedented sharps heterogeneities were evidenced with the highlighting of an in-depth mechanical gradient and a soft central furrow that were maintained throughout the plant development despite the overall increase in elastic modulus. In addition, we demonstrated that these local mechanical areas are correlated to chemical and structural gradients. C_LIO_LIThis study shed light on a fine tuning of mechanical properties of cuticle through the modulation of their architecture, providing new insight for our understanding of structure-function relationships of plant cuticle and for the design of biosinpired material. C_LI

plant biology↗