Biology subjects

Borowsky, A. T.

Publications and source records attributed to Borowsky, A. T..

5 recordsLinked to original sources

bioRxiv2025

Drought drives reversible disengagement of root-mycorrhizal symbiosis

The increasing frequency and severity of droughts pose a major threat to agriculture, food security and ecosystems. Plants respond to water deficit by adjusting growth and metabolism to enhance survival; these adjustments impact the soil microorganisms interacting with plant roots. Plants establish symbiotic relationships with arbuscular mycorrhizal fungi which supply soil nutrients in exchange for carbon metabolites via an intricate dual-species interface within roots. These fungi are dependent upon host-derived photosynthates and are thus potentially vulnerable to plant perturbations during drought. Here, we demonstrate that the plant-mycorrhizal relationship is dynamic when water becomes limiting. During water deficit, rice de-prioritizes nutrient acquisition gene regulatory networks, including its AM symbiotic program, in a strategy conserved with tomato. The fungal symbiont correspondingly represses its growth, undergoing metabolic quiescence, coupled with decommissioning of hyphae within the hosts root. Following re-watering, the host re-engages with its partner fungus, re-invigorating fungal growth and arbuscule establishment. This coordinate, reversible and enduring inter-organismal association may aid host survival under transient stress, but suggests that mutualisms in native and crop plants are potentially fragile in increasingly erratic climates.

plant biology↗

bioRxiv2022

A suberized exodermis is required for tomato drought tolerance

Plant roots integrate environmental signals and developmental programs using exquisite spatiotemporal control. This is apparent in the deposition of suberin, an apoplastic diffusion barrier, which regulates the entry and exit of water, solutes and gases, and is environmentally plastic. Suberin is considered a hallmark of endodermal differentiation, but we find that it is absent in the tomato endodermis during normal development. Instead, suberin is present in the exodermis, a cell type that is absent in the model organism Arabidopsis thaliana. Here, we uncover genes driving exodermal suberization and describe its effects on drought responses in tomato, unravelling the similarities and differences with the paradigmatic Arabidopsis endodermis. Cellular resolution imaging, gene expression, and mutant analyses reveal loss of this program from the endodermis, and its co-option in the exodermis. Functional genetic analyses of the tomato MYB92 transcription factor and ASFT enzyme demonstrate the importance of exodermal suberin for a plant water-deficit response. Controlling the degree of exodermal suberization could be a new strategy for breeding climate-resilient plants.

plant biology↗

bioRxiv2020

Innovation, conservation and repurposing of gene function in plant root cell type development

Plant species have evolved myriads of solutions to adapt to dynamic environments, including complex cell type development and regulation. To understand this diversity, we profiled tomato root cell type translatomes and chromatin accessibility. Using xylem differentiation in tomato, relative to Arabidopsis, examples of functional innovation, repurposing and conservation of transcription factors are described. Repurposing and innovation of genes are further observed within an exodermis regulatory network and illustrate its function. Translatome analyses of rice, tomato and Arabidopsis tissues suggest that root meristems are more conserved, and that the functions of constitutively expressed genes are more conserved than those of cell type/tissue-enriched genes. These observations suggest that higher-order properties of cell type and pan-cell type regulation are conserved between plants and animals. One Sentence SummaryPan-species cell type translatome and chromatin accessibility data reveal novelty, conservation and repurposing of gene function.

genomics↗

bioRxiv2019

Recurrent loss of abaA, a master regulator of asexual development in filamentous fungi, correlates with changes in genomic and morphological traits

Gene regulatory networks (GRNs) drive developmental and cellular differentiation, and variation in their architectures gives rise to morphological diversity. Pioneering studies in Aspergillus fungi, coupled with subsequent work in other filamentous fungi, have shown that the GRN governed by the BrlA, AbaA, and WetA proteins controls the development of the asexual fruiting body or conidiophore. A specific aspect of conidiophore development is the production of phialides, conidiophore structures that are under the developmental control of AbaA and function to repetitively generate spores. Fungal genome sequencing has revealed that some filamentous fungi lack abaA, and also produce asexual structures that lack phialides, raising the hypothesis that abaA loss is functionally linked to diversity in asexual fruiting body morphology. To examine this hypothesis, we carried out an extensive search for the abaA gene across 241 genomes of species from the fungal subphylum Pezizomycotina. We found that abaA was independently lost in four lineages of Eurotiomycetes, including from all sequenced species within the order Onygenales, and that all four lineages that have lost abaA also lack the ability to form phialides. Genetic restoration of abaA from Aspergillus nidulans into Histoplasma capsulatum, a pathogenic species from the order Onygenales that lacks an endogenous copy of abaA, did not alter Histoplasma conidiation morphology but resulted in a marked increase in spore viability. We also discovered that species lacking abaA contain fewer AbaA binding motifs in the regulatory regions of orthologs of some AbaA target genes, suggesting that the asexual fruiting body GRN of organisms that have lost abaA has been rewired. Our results provide an illustration of how repeated losses of a key regulatory transcription factor and concomitant changes in non-coding regulatory regions of the genome have contributed to the diversity of an iconic fungal morphological trait.\n\nAuthor SummaryFungi exhibit tremendous variation in their asexual fruiting bodies. For example, whereas some fungi form complex fruiting bodies whose tips repeatedly generate and release spores, others produce single spores in the absence of a specialized structure. To gain insights into the molecular differences that underpin fungal asexual fruiting body diversity, we examined the genomes of hundreds of filamentous fungi for the presence of abaA, a master regulatory gene previously shown to control the development of fungal asexual fruiting bodies. We found that abaA was repeatedly lost during fungal evolution, including in a lineage of human pathogenic fungi, and that the loss of the gene was always associated with the loss of specialized structures in fungal asexual fruiting bodies. Reintroduction of abaA into the human pathogenic fungus Histoplasma capsulatum, which normally lacks the regulator, did not result in a change in the spore-producing structure but did increase spore outgrowth. Based on these results, we hypothesize that the loss of the master regulatory gene abaA has contributed to the observed diversity of fungal fruiting body morphology. This work advances our understanding of how fungal developmental networks evolve over time and advances our understanding of how infectious spores form in pathogenic fungi.

evolutionary biology↗

bioRxiv2016

A global co-expression network approach for connecting genes to specialized metabolic pathways in plants

Plants produce a tremendous diversity of specialized metabolites (SMs) to interact with and manage their environment. A major challenge hindering efforts to tap this seemingly boundless source of pharmacopeia is the identification of SM pathways and their constituent genes. Given the well-established observation that the genes comprising a SM pathway are co-regulated in response to specific environmental conditions, we hypothesized that genes from a given SM pathway would form tight associations (modules) with each other in gene co-expression networks, facilitating their identification. To evaluate this hypothesis, we used 10 global co-expression datasets--each a meta-analysis of hundreds to thousands of expression experiments--across eight plant model organisms to identify hundreds of modules of co-expressed genes for each species. In support of our hypothesis, 15.3-52.6% of modules contained two or more known SM biosynthetic genes (e.g., cytochrome P450s, terpene synthases, and chalcone synthases), and module genes were enriched in SM functions (e.g., glucoside and flavonoid biosynthesis). Moreover, modules recovered many experimentally validated SM pathways in these plants, including all six known to form biosynthetic gene clusters (BGCs). In contrast, genes predicted based on physical proximity on a chromosome to form plant BGCs were no more co-expressed than the null distribution for neighboring genes. These results not only suggest that most predicted plant BGCs do not represent genuine SM pathways but also argue that BGCs are unlikely to be a hallmark of plant specialized metabolism. We submit that global gene co-expression is a rich, but largely untapped, data source for discovering the genetic basis and architecture of plant natural products, which can be applied even without knowledge of the genome sequence.

plant biology↗