Biology subjects

Arteaga-Vazquez, M. A.

Publications and source records attributed to Arteaga-Vazquez, M. A..

5 recordsLinked to original sources

bioRxiv2024

The MpANT-auxin loop modulates Marchantia polymorpha development

AINTEGUMENTA-LIKE/PLETHORA (APB) genes are considered part of the ancestral developmental toolkit in land plants. In Arabidopsis thaliana, these transcription factors are induced by auxin and are primarily expressed in tissues with actively dividing cells, where they play essential roles in organ development. Marchantia polymorpha, a liverwort that diverged from A. thaliana early in embryophyte evolution, possesses a single APB ortholog, MpAINTEGUMENTA (MpANT), encoded in its genome. In this study, we aimed to characterize the function of MpANT. Analysis of a transcriptional fusion line indicates that MpANT is predominantly expressed in the meristematic region. We report that the MpANT promoter region contains several cis-acting Auxin Responsive Elements (AREs) and demonstrate that its expression, which occurs predominantly in meristematic regions, is significantly altered by addition of exogenous auxin and inhibition of auxin transport. These findings indicate that MpANT acts downstream of Auxin Response Factors (ARFs) and auxin signaling. Analyses of loss- and gain-of-function MpANT alleles highlight the importance of this transcription factor in meristem maintenance and cell proliferation. Additionally, we found that MpANT acts upstream of the auxin transporter MpPIN1 by influencing auxin distribution. Taken together, our findings reveal a feedforward regulatory loop involving auxin, MpANT, and MpPIN1 that is important for Marchantia development.

plant biology↗

bioRxiv2023

Control of cell fate specification and patterning by an ancestral microRNA

The formation of an organized body requires the establishment and maintenance of cells with structural and functional distinctive characteristics. A central question in developmental biology is how changes in the regulation of genes drive cell specification and patterning1. microRNAs (miRNAs) are small non-coding RNAs that regulate development through mRNA cleavage and/or translational repression2. In plants, miRNAs regulate key aspects including growth, development, stem cell maintenance, vegetative phase change, leaf morphogenesis, floral organ formation and flowering time3. Biogenesis of plant miRNAs depends on the activity of DICER-LIKE 1 (DCL1), an RNase type III endonuclease that processes double stranded RNA to give rise to mature miRNAs 4. The genomes of todays flora contain at least one bona fide copy of DCL1 5,6. Using Marchantia polymorpha -a model bryophyte that allows comparative approaches to infer characteristics of the ancestral land plant-, we demonstrate that MpDCL1a is required for the biogenesis of miRNAs and uncovered a central role for miR166/Homeodomain Zipper Class III-regulated auxin synthesis in the specification of cell identity, patterning, meristem function, laminar expansion and the development of the body in the last common ancestor of extant land plants.

plant biology↗

bioRxiv2019

Mechanisms Underlying the Enhanced Biomass and Abiotic Stress Tolerance Phenotypes of an Arabidopsis MIOX Over expresser

Myo-inositol oxygenase (MIOX) is the first enzyme in the inositol route to ascorbate (L-ascorbic acid, AsA, vitamin C). We have previously shown that Arabidopsis plants constitutively expressing MIOX have elevated foliar AsA content and displayed enhanced growth rate, biomass accumulation, and increased tolerance to multiple abiotic stresses. In this work, we used a combination of transcriptomics, chromatography, microscopy, and physiological measurements to gain a deeper understanding of the underlying mechanisms mediating the phenotype of the AtMIOX4 line. Transcritpomic analysis revealed increased expression of genes involved in auxin synthesis, hydrolysis, transport, and metabolism, which are supported by elevated auxin levels both in vitro and in vivo, and confirmed by assays demonstrating their effect on epidermal cell elongation in the AtMIOX4 over-expresser plants. Additionally, we detected up-regulation of transcripts involved in photosynthesis that was validated by increased efficiency of the photosystem II and proton motive force. We also found increased expression of amylase leading to higher intracellular glucose levels. Multiple gene families conferring plants tolerance to cold, water limitation, and heat stresses were found to be elevated in the AtMIOX4 line. Interestingly, the high AsA plants also displayed up-regulation of transcripts and hormones involved in defense including jasmonates, defensin, glucosinolates, and transcription factors that are known to be important for biotic stress tolerance. These results overall indicate that elevated levels of auxin and glucose, and enhanced photosynthetic efficiency in combination with up-regulation of abiotic stresses response genes underly the higher growth rate and abiotic stresses tolerance phenotype of the AtMIOX4 over-expressers.

plant biology↗

bioRxiv2018

Loss of CG methylation in Marchantia polymorpha causes disorganization of cell division and reveals unique DNA methylation regulatory mechanisms of non-CG methylation.

DNA methylation is an epigenetic mark that ensures silencing of transposable elements (TEs) and affects gene expression in many organisms. The function of different DNA methylation regulatory pathways has been largely characterized in the model plant Arabidopsis thaliana. However, far less is known about DNA methylation regulation and functions in basal land plants. Here we focus on the liverwort Marchantia polymorpha, an emerging model species that represents a basal lineage of land plants. We identified MpMET, the M. polymorpha orthologue of the METHYLTRANSFERASE 1 (MET1) gene required for maintenance of methylation at CG sites in angiosperms. We generated Mpmet mutants using the CRISPR/Cas9 system, which showed a significant loss of CG methylation and severe morphological changes and developmental defects. The mutants developed many adventitious shoot-like structures, suggesting that MpMET is required for maintaining differentiated cellular identities in the gametophyte. Numerous TEs were up-regulated, even though non-CG methylation was highly increased at TEs in the Mpmet mutants. Closer inspection of CHG methylation revealed features unique to M. polymorpha. Methylation of CCG sites in M. polymorpha does not depend on MET1, unlike in A. thaliana and Physcomitrella patens. Furthermore, unlike A. thaliana, M. polymorpha shows higher methylation level at CAG sites than at other CHG contexts and CAG/CTG sites are mostly methylated asymmetrically. Interestingly, CAG and CTG methylation reached comparable levels and symmetry upon loss of CG methylation. Our results highlight the diversity of non-CG methylation regulatory mechanisms in plants.

plant biology↗

bioRxiv2017

Marchantia liverworts as a proxy to plants basal microbiomes.

Microbiomes influence plant development, establishment, nutrient acquisition, pathogen defense, and the myriad of roles that ultimately impacts plant health. Plants microbiome are shaped through interactions between the microbes (ranging from cooperative functions to chemical warfare) and a selection process entailed by the host plants that distinguishes between pathogens, commensals, symbionts and transient bacteria. The soil is a primary source for microbes colonizing plants, along with other environmental sources including rain and interactions with other organisms. In this work, we explore the microbiomes through massive sequencing of the 16S rRNA gene in the eldest terrestrial plants: Marchantia liverworts. We compared microbiomes from M. polymorpha, and M. paleacea plants collected in the wild and their soils, all together luckily in the same geographical location (sympatric) thus reducing geographic effects; and also from plants grown in vitro and established from gemmae obtained from the same population of wild plants. Qualitative and quantitative microbiome analysis allowed us to identify microbes conserved in both native and in vitro Marchantia species. While M. polymorpha native plants microbiomes richness is reduced about M. paleacea, containing almost half of the Operative Taxonomic Units (OTUs) observed in M. paleacea, M. polymorpha grown in vitro exhibits larger OTUs. This diversity differences might be the result of impairment to recognize their microbial partners and being an open niche for opportunistic bacteria. The main OTUs in Marchantia microbiomes were assigned to the genera: Methylobacterium, Rhizobium, Paenibacillus, Lysobacter, Pirellula, Steroidobacter, and Bryobacter. The assigned genera correspond to bacteria capable of plant-growth promotion, complex exudates degradation, nitrogen fixation, methylotrophs, and disease-suppressive bacteria, all hosted in the relatively simple anatomy of the plant that provides refuge on their surfaces, rhizoids, and multiple gas chambers that work as specialized niches for different bacterial groups. Marchantia is a promising model to study not only long-term relationships between plants and their microbes but also the transgenerational impact of microbiomes because of Marchantia long 450 million years under climate change conditions testing microbiome configurations.

microbiology↗