Biology subjects

Vardanega, I.

Publications and source records attributed to Vardanega, I..

5 recordsLinked to original sources

bioRxiv2025

The developing leaf of the wild grass Brachypodium distachyon at single-cell resolution

Leaves are the plants main photosynthetic organs and drive Earths primary production. Grasses form longitudinal leaves with parallel venation and graminoid stomata. Yet, how distinct leaf tissues coordinatively develop to build functional grass leaf anatomy is not well understood. Here, we decoded the developing grass leaf from vegetative meristems to mature tissues using single-cell RNA-sequencing in the wild grass Brachypodium distachyon. In-depth analysis of epidermal clusters and multiplexed whole-mount RNA-fluorescence in situ hybridization resolved most epidermal lineages and confirmed them in planta. Gene regulatory network analysis distinguished the targetome of the two co-expressed, yet functionally divergent stomatal transcription factors BdMUTE and BdFAMA. Finally, we used our dataset to identify and functionally describe BdGRAS32s role in cell division inhibition and a stomata-specific function for a cell wall modifying enzyme. Together, our single-cell grass leaf atlas enables the dissection of developmental processes that shape the leaf sustaining global food production.

plant biology↗

bioRxiv2025

Imputation integrates single-cell and spatial gene expression data to resolve transcriptional networks in barley shoot meristem development

Grass inflorescences are composite structures, featuring complex sets of meristems as stem cell niches that are initiated in a repetitive manner. Meristems differ in identity and longevity, generate branches or split to form flower meristems that finally produce seeds. Within meristems, distinct cell types are determined by positional information and the regional activity of gene regulatory networks. Understanding these local microenvironments requires precise spatio-temporal information on gene expression profiles, which current technology cannot achieve. Here we investigate transcriptional changes during barley development, from the specification of meristem and organ founder cells to the initiation of distinct floral organs, based on an imputation approach integrating deep single-cell RNA sequencing with spatial gene expression data. The expression profiles of more than 40.000 genes can be analysed at cellular resolution in multiple barley tissues using the web-based graphical interface BARVISTA, which enables precise virtual microdissection to analyse any sub-ensemble of cells. Our study pinpoints previously inaccessible key transcriptional events in founder cells during primordia initiation and specification, characterises complex branching mutant phenotypes by barcoding gene expression profiles, and defines spatio-temporal trajectories during flower development. We thus uncover the genetic basis of complex developmental processes, providing novel opportunities for precisely targeted manipulation of barley traits.

plant biology↗

bioRxiv2024

CLAVATA signalling shapes barley inflorescence architecture by controlling activity and determinacy of shoot apical and rachilla meristems

Grasses exhibit a large variety of diverse inflorescence architectures, from complex branched inflorescences in Oryzeae (rice) to simple spike-type inflorescences in Triticeae (e.g. barley, wheat). Inflorescence architecture depends on shape, longevity and determinacy of meristems that direct growth of the main rachis and lateral branches, but how individual meristem activities are determined and integrated within complex inflorescences is not yet understood. We found that activity of distinct meristems in the barley inflorescence is coordinated by a signalling pathway comprising the receptor like kinase Hordeum vulgare CLAVATA1 (HvCLV1) and the secreted CLAVATA3/ENDOSPERM SURROUNDING REGION (CLE)-family peptide FON2- LIKE CLE PROTEIN1 (HvFCP1). HvFCP1 interacts with HvCLV1 to promote spikelet formation but restricts inflorescence meristem and rachilla meristem proliferation. Hvfcp1 or Hvclv1 mutants generate branched inflorescences with additional rows of spikelets and supernumerary florets. Transcriptome analysis reveals that HvFCP1/HvCLV1 signalling controls inflorescence branching through the regulation of trehalose-6-phosphate synthesis and sugar transport. Our discoveries reveal the potential to engineer barley inflorescence architecture by manipulating regulation of distinct meristem activities.

plant biology↗

bioRxiv2023

The transcriptome landscape of developing barley seeds reveals H3K27me3 dynamics in endosperm tissues

Cereal grains are an important food and feed. To provide comprehensive spatiotemporal information about biological processes in developing seeds of cultivated barley, we performed a transcriptomic study of the embryo, endosperm, and seed maternal tissues collected from 4 to 32 days after pollination. Weighted gene co-expression network and motif enrichment analyses pointed out specific groups of genes and transcription factors with possible impacts on regulating barley seed tissue development. We defined a set of tissue-specific marker genes and families of transcription factors for functional studies of the pathways controlling barley grain development. Assessment of selected groups of chromatin regulators revealed that epigenetic processes are highly dynamic and likely to play a major role during barley endosperm development. Repressive modification H3K27me3 is globally reduced in endosperm tissues and at specific developmental and storage compound genes. Altogether, this atlas uncovers the complexity of the developmental regulation of gene expression in barley grains. TeaserSpatiotemporal profiling of developing barley seeds revealed loss of H3K27me3 and changes in gene expression in endosperm.

plant biology↗

bioRxiv2021

ENHANCED GRAVITROPISM 2 encodes a STERILE ALPHA MOTIVE containing protein that controls root growth angle in barley and wheat

The root growth angle defines how roots grow towards the gravity vector and is among the most important determinants of root system architecture. It controls water uptake capacity, nutrient use efficiency, stress resilience and as a consequence yield of crop plants. We demonstrated that the egt2 (enhanced gravitropism 2) mutant of barley exhibits steeper root growth of seminal and lateral roots and an auxin independent higher responsiveness to gravity compared to wild type plants. We cloned the EGT2 gene by a combination of bulked segregant analysis and whole genome sequencing. Subsequent validation experiments by an independent CRISPR/Cas9 mutant allele demonstrated that egt2 encodes a STERILE ALPHA MOTIF domain containing protein. In situ hybridization experiments illustrated that EGT2 is expressed from the root cap to the elongation zone. Subcellular localization experiments revealed that EGT2 localizes to the nucleus and cytoplasm. We demonstrated the evolutionary conserved role of EGT2 in root growth angle control between barley and wheat by knocking out the EGT2 orthologs in the A and B genomes of tetraploid durum wheat. By combining laser capture microdissection with RNA-seq, we observed that seven expansin genes were transcriptionally downregulated in the elongation zone. This is consistent with a role of EGT2 in this region of the root where the effect of gravity sensing is executed by differential cell elongation. Our findings suggest that EGT2 is an evolutionary conserved regulator of root growth angle in barley and wheat that could be a valuable target for root-based crop improvement strategies in cereals. Significance StatementTo date the potential of utilizing root traits in plant breeding remains largely untapped. In this study we cloned and characterized the ENHANCED GRAVITROPISM2 (EGT2) gene of barley that encodes a STERILE ALPHA MOTIF domain containing protein. We demonstrated that EGT2 is a key gene of root growth angle regulation in response to gravity which is conserved in barley and wheat and could be a promising target for crop improvement in cereals.

plant biology↗