Biology subjects

Illouz-Eliaz, N.

Publications and source records attributed to Illouz-Eliaz, N..

9 recordsLinked to original sources

bioRxiv2026

Transient cell states encode positional information to direct asymmetric growth

How tissues generate asymmetric growth from spatially and temporally restricted signals remains a fundamental challenge in developmental biology. We show that transient cell states encode positional information that instructs asymmetric growth in plants. Using spatial single-cell transcriptomics and multi-omics, we uncover a surprisingly complex landscape of transient cell states in the apical hook, including a previously unrecognized population in the apical hypocotyl region that integrates developmental and hormonal cues and bifurcates into opposing growth trajectories. Gene regulatory network analysis and functional perturbation establish GATA TRANSCRIPTION FACTOR 2 (GATA2) as a central regulator that promotes cell elongation through gibberellin signaling. These results reveal that diverse, spatially localized transient cell states function as regulatory hubs that convert positional information into divergent growth programs, providing a unifying framework for how dynamic cellular states shape organ morphology.

plant biology↗

bioRxiv2025

Stress drives plasticity in leaf maturation transcriptional dynamics

Leaf development is dynamic, adapting to environmental stress to optimize resource use. For example, in response to drought, Arabidopsis restricts leaf growth to enhance water use efficiency. While this plastic response is well described at the physiological level, the underlying transcriptional changes that facilitate adjustments in leaf development in response to stress remain poorly described. By constructing a [~]1 million single-nuclei transcriptome atlas, we demonstrate that drought stress limits leaf growth by advancing transcriptional responses related to maturation and aging. Notably, we find that these transcriptional changes scale with environmental stress, and help explain how shoot size can decline proportionally with stress intensity. Leveraging these insights, we increased leaf growth under stress by cell-type targeted upregulation of FERRIC REDUCTION OXIDASE 6 in the mesophyll.

plant biology↗

bioRxiv2023

A Single-Nucleus Atlas of Seed-to-Seed Development in Arabidopsis

Extensive studies of the reference plant Arabidopsis have enabled a deep understanding of tissues throughout development, yet a census of cell types and states throughout development is lacking. Here, we present a single-nucleus transcriptome atlas of seed-to-seed development employing over 800,000 nuclei, encompassing a diverse set of tissues across ten developmental stages, with spatial transcriptomic validation of the dynamic seed and silique. Cross-organ analyses revealed transcriptional conservation of cell types throughout development and heterogeneity within individual cell types influenced by organ-of-origin and developmental timing, including groups of transcription factors, suggesting gatekeeping by transcription factor activation. This atlas provides a resource for the study of cell type specification throughout the development continuum and a reference for stimulus-response and genetic perturbations at the single-cell resolution.

plant biology↗

bioRxiv2023

Drought Recovery Induced Immunity Confers Pathogen Resistance

All organisms experience stress as an inevitable part of life, from single-celled microorganisms to complex multicellular beings. The ability to recover from stress is a fundamental trait that determines the overall resilience of an organism, yet stress recovery is understudied. To begin unraveling the stress recovery process we studies recovery from drought stress in Arabidopsis thaliana. We performed a fine-scale time series of bulk RNA sequencing starting 15 minutes after rehydration following moderate drought. We reveal that drought recovery is a rapid process involving the activation of thousands of recovery-specific genes. To capture these rapid recovery responses in different leaf cell types, we performed single-nucleus transcriptome analysis at the onset of post-drought recovery, identifying a cell type-specific transcriptional state developing within 15 minutes of rehydration independently across cell types. Furthermore, we reveal a recovery-induced activation of the immune system that occurs independent of infection, which enhances pathogen resistance in vivo in A. thaliana, wild tomato (Solanum pennellii) and domesticated tomato (Solanum lycopersicum cv. M82). Since rehydration promotes microbial proliferation and thereby increases the risk of infection1-2, drought recovery-induced immunity may be crucial for plant survival in natural environments. These findings indicate that drought recovery coincides with a preventive defense response, unraveling the complex regulatory mechanisms that facilitate stress recovery in different plant cell types.

plant biology↗

bioRxiv2022

Mimicking genuine drought responses using a high throughput plate assay

Soil-free assays that induce water stress are routinely used to investigate drought responses in the plant Arabidopsis thaliana. Due to their ease of use, the research community often relies on polyethylene glycol (PEG), mannitol and salt (NaCl) treatments to reduce the water potential of agar media, and thus induce drought conditions in the laboratory. However, while these types of stress can create phenotypes that resemble those of water deficit experienced by soil-grown plants, it remains unclear how these treatments compare at the transcriptional level. Here, we demonstrate that these different methods of lowering water potential elicit both shared and distinct transcriptional responses in Arabidopsis shoot and root tissue. When we compared these transcriptional responses to those found in Arabidopsis roots subject to vermiculite drying, we discovered many genes induced by vermiculite drying were repressed by low water potential treatments on agar plates (and vice versa). Additionally, we also tested another method for lowering water potential of agar media. By increasing the nutrient content and tensile strength of agar, we show the hard agar (HA) treatment can be leveraged as a high-throughput assay to investigate natural variation in Arabidopsis growth responses to low water potential.

plant biology↗

bioRxiv2021

Inhibition of gibberellin accumulation by water deficiency promotes fast and long-term 'drought avoidance' responses in tomato

Plants reduce transpiration to avoid dehydration during drought episodes by stomatal closure and inhibition of canopy growth. While abscisic acid (ABA) has a primary role in drought avoidance, previous studies suggest that gibberellin (GA), might also be involved. Here we show in tomato (Solanum lycopersicum) that shortage of water inhibited the expression of the GA biosynthesis genes GA20 oxidase1 (GA20ox1) and GA20ox2 and induced the GA-deactivating gene GA2ox7 in leaves and guard cells, resulting in reduced bioactive GA levels. Drought regulation of GA metabolism was mediated by ABA-dependent and independent pathways, and by the transcription factor DEHYDRATION RESPONSIVE ELEMENT BINDING (DREB), TINY1. Mutations in GA20ox1 and GA20ox2 reduced water loss due to the smaller canopy area. On the other hand, loss of GA2ox7 did not affect leaf size, but attenuated stomatal response to water deficiency; during soil dehydration, ga2ox7 plants closed their stomata and reduced transpiration later than WT, suggesting that ga2ox7 stomata are hyposensitive to soil dehydration. Together, the results suggest that drought-induced GA deactivation in guard cells contributes to stomatal closure at the early stages of soil dehydration, whereas inhibition of GA synthesis in leaves promotes mainly the long-term reduction in canopy growth to reduce transpiration area.

molecular biology↗

bioRxiv2020

Underground gibberellin activity: differential gibberellin response in tomato shoots and roots

Gibberellins (GAs) are growth-promoting hormones that regulate organ growth, mainly via cell elongation. Contradicting reports leave an open question of whether GA is as important for root elongation as it is for stem elongation. Here we have addressed this question focusing on tomato (Solanum lycopersicum) primary-root elongation. We used a combination of physiological, molecular and genetic approaches to tackle this question. Tomato has three GA receptors; GID1a, GID1b1 and GID1b2. The loss of all three receptors, strongly suppressed stem elongation and leaf expansion, but had a relatively minor effect on primary root elongation. The effect of GA on cell elongation and gene-expression was much weaker in roots, than in shoots, reaching saturation at lower hormone concentrations. Our results imply that this differential response to GA in shoots and roots is caused by the lower expression of the dominant GA receptor GID1a in roots. We show that the differential activity of GA between shoots and roots affects root-to-shoot ratio, and speculate that this evolved as an adaptive mechanism to changing environments.

plant biology↗

bioRxiv2020

The tomato DELLA protein PROCERA promotes ABA responses in guard cells by upregulating ABA transporter

Plants reduce transpiration to avoid drought stress by stomatal closure. While abscisic acid (ABA) has a central role in the regulation of stomatal closure under water-deficit conditions, we demonstrated in tomato that the gibberellin (GA) response inhibitor, the DELLA protein PROCERA (PRO), promotes ABA-induced stomatal closure and gene transcription in guard cells. To study how PRO affects stomatal closure, we performed RNAseq analysis of isolated guard cells and identified the ABA transporters ABA-IMPORTING TRANSPORTER1.1 (AIT1.1) and AIT1.2, also called in Arabidopsis NPF4.6, as upregulated by PRO. Tomato has four AIT1 genes, but only AIT1.1 and AIT1.2 were upregulated by PRO, and only AIT1.1 exhibited high expression in guard cells. Functional analysis of AIT1.1 in yeast confirmed its activity as an ABA transporter, possibly importer. CRISPR-Cas9-defrived ait1.1 mutant exhibited increased transpiration, larger stomatal aperture and reduced response to ABA. Moreover, ait1.1 suppressed the promoting effects of PRO on ABA-induced stomatal closure and gene expression in guard cells. The negative interaction between GA and ABA has been studied for many years in numerous plant species. These studies suggest that the crosstalk is mediated by changes in hormone biosynthesis and signaling. Our results suggest that it is also mediated by changes in hormone transport. One-sentence SummaryThe tomato DELLA protein PROCERA promoted abscisic acid-induced stomatal closure and gene expression by upregulating the expression of the ABA transporter ABA-IMPORTING TRANSPORTER 1 in guard cells.

plant biology↗

bioRxiv2020

Mutations in the tomato gibberellin receptors suppresses xylem proliferation and reduces water loss under water-deficit conditions

Low gibberellin (GA) activity in tomato (Solanum lycopersicum) inhibits leaf expansion and reduces stomatal conductance. These lead to lower transpiration and improve water status under transient drought conditions. Tomato has three GIBBERELLIN-INSENSITIVE DWARF1 (GID1) GA receptors with overlapping activities and high redundancy. We have tested whether mutation in a single GID1 reduces transpiration without affecting growth and productivity. CRISPR-Cas9 gid1 mutants were able to maintain higher leaf water content under water-deficit conditions. Moreover, while gid1a exhibited normal growth, it showed reduced whole plant transpiration and better recovery from dehydration. Mutation in GID1a inhibited xylem vessels proliferation that led to lower hydraulic conductance. In stronger GA mutants, we also found reduced xylem vessel expansion. These results suggest that low GA activity affects transpiration by multiple mechanisms; it reduces leaf area, promotes stomatal closure and reduces xylem proliferation and expansion and as a result, xylem hydraulic conductance. We further examined if gid1a perform better than the control M82 in the field. Under these conditions, the high redundancy of GID1s was lost and gid1a plants were semi-dwarf, but their productivity was not affected. Although gid1a did not perform better under drought conditions in the field, it exhibited higher harvest index. HighlightThe loss of the tomato gibberellin receptors GID1s reduced xylem proliferation and xylem hydraulic conductance. These contribute to the effect of low gibberellin activity on water loss under water-deficit condition.

plant biology↗