Biology subjects

Jawdy, S.

Publications and source records attributed to Jawdy, S..

4 recordsLinked to original sources

bioRxiv2025

Microbial Modulation of Host Plant Proteasome Activity Improves Heat Stress Tolerance

Global climate change marked by rising temperatures and increasingly frequent, severe heat waves, threatens plant health, productivity, and ecosystem function. Beneficial plant-microbe associations are increasingly recognized for their role in mitigating abiotic stress, yet the molecular mechanisms underlying microbially-conferred thermotolerance remain poorly understood. Here, we developed a population-based assay using Sphagnum peat mosses, a key species in peatland ecosystems that sequester 33-50% of the worlds soil carbon as recalcitrant peat, to perform microbiome transfers and assess microbial contributions to heat resilience. Strain-based assays in Sphagnum and Arabidopsis identified Variovorax as a key thermotolerance-enhancing microbe and identified ECM29, a proteasome-associated protein, as critical for this interaction. In Arabidopsis, Variovorax sp. CF313 association led to ECM29 preferentially binding the RPT1 subunit of the 19S regulatory particle, inhibiting 20S proteasome gate opening and slightly reducing proteasomal activity. This results in the accumulation of ubiquitinated proteins and induces HSP70 transcription, priming the host for heat shock stress even in the absence of prior heat exposure. These findings establish ECM29 as a key regulator of proteasome activity in response to microbial interactions, highlighting a previously unknown mechanism by which microbes enhance plant thermotolerance. More broadly, this work highlights the importance of leveraging natural systems and ecologically relevant models to identify strategies for enhancing plant and ecosystem resilience to a changing climate. Significance StatementGlobal climate change poses severe threats to plant health and productivity, with cascading impacts on ecosystems. Beneficial plant-microbe interactions offer promising strategies to mitigate abiotic stress, yet the molecular mechanisms often remain unclear. This study uncovers a novel thermotolerance mechanism mediated by Variovorax modulating the plant host proteasome. Using a QTL derived from Sphagnum peat mosses, and tested within a genetically tractable Arabidopsis model, we identified ECM29, a highly conserved protein across diverse plant species, as a key regulator of proteasome activity. ECM29 primes plants for heat stress by inducing HSP70 transcription through proteasome modulation. Additionally, we demonstrated that ECM29 is required for the host to receive microbially conferred thermotolerance, but is not necessary for innate priming to heat stress. These findings highlight the potential of leveraging natural systems and ecologically relevant species to develop innovative genetic models, advancing plant resilience and productivity in a warming world.

plant biology↗

bioRxiv2024

Catabolic pathway acquisition by soil pseudomonads readily enables growth with salicyl alcohol but does not affect colonization of Populus roots

Horizontal gene transfer (HGT) is a fundamental evolutionary process that plays a key role in bacterial evolution. The likelihood of a successful transfer event is expected to depend on the precise balance of costs and benefits resulting from pathway acquisition. Most experimental analyses of HGT have focused on phenotypes that have large fitness benefits under appropriate selective conditions, such as antibiotic resistance. However, many examples of HGT involve phenotypes that are predicted to provide smaller benefits, such as the ability to catabolize additional carbon sources. We have experimentally reproduced one such HGT event in the laboratory, studying the effects of transferring a pathway for catabolism of the plant-derived aromatic compound salicyl alcohol into soil isolates from the Pseudomonas genus. We find that pathway acquisition enables rapid catabolism of salicyl alcohol with only minor disruptions to existing metabolic and regulatory networks of the new host. However, this new catabolic potential does not confer a measurable fitness advantage during competitive growth in the rhizosphere. We conclude that the phenotype of salicyl alcohol catabolism is readily transferred by HGT but is selectively neutral under environmentally-relevant conditions. We propose that this condition is common and that HGT of many pathways will be self-limiting, because the selective benefits are small and negative frequency-dependent.

microbiology↗

bioRxiv2023

The Plasminogen-Apple-Nematode (PAN) domain suppresses JA/ET defense pathways in plants

Suppression of immune response is a phenomenon that enables biological processes such as gamete fertilization, cell growth, cell proliferation, endophyte recruitment, parasitism, and pathogenesis. Here, we show for the first time that the Plasminogen-Apple-Nematode (PAN) domain present in G-type lectin receptor-like kinases is essential for immunosuppression in plants. Defense pathways involving jasmonic acid and ethylene are critical for plant immunity against microbes, necrotrophic pathogens, parasites, and insects. Using two Salix purpurea G-type lectin receptor kinases, we demonstrated that intact PAN domains suppress jasmonic acid and ethylene signaling in Arabidopsis and tobacco. Variants of the same receptors with mutated residues in this domain could trigger induction of both defense pathways. Assessment of signaling processes revealed significant differences between receptors with intact and mutated PAN domain in MAPK phosphorylation, global transcriptional reprogramming, induction of downstream signaling components, hormone biosynthesis and resistance to Botrytis cinerea. Further, we demonstrated that the domain is required for oligomerization, ubiquitination, and proteolytic degradation of these receptors. These processes were completely disrupted when conserved residues in the domain were mutated. Additionally, we have tested the hypothesis in recently characterized Arabidopsis mutant which has predicted PAN domain and negatively regulates plant immunity against root nematodes. ern1.1 mutant complemented with mutated PAN shows triggered immune response with elevated WRKY33 expression, hyperphosphorylation of MAPK and resistant to necrotrophic fungus Botrytis cinerea. Collectively, our results suggest that ubiquitination and proteolytic degradation mediated by the PAN domain plays a role in receptor turn-over to suppress jasmonic acid and ethylene defense signaling in plants.

plant biology↗

bioRxiv2020

Sphagnum peat moss thermotolerance is modulated by the microbiome

Sphagnum peat mosses is a major genus that is common to peatland ecosystems, where the species contribute to key biogeochemical processes including the uptake and long-term storage of atmospheric carbon. Warming threatens Sphagnum mosses and the peatland ecosystems in which they reside, potentially affecting the fate of vast global carbon stores. The competitive success of Sphagnum species is attributed in part to their symbiotic interactions with microbial associates. These microbes have the potential to rapidly respond to environmental change, thereby helping their host plants survive under changing environmental conditions. To investigate the importance of microbiome thermal origin on host plant thermotolerance, we mechanically separated the microbiome from Sphagnum plants residing in a whole-ecosystem warming study, transferred the component microbes to germ-free plants, and exposed the new hosts to temperature stress. Although warming decreased plant photosynthesis and growth in germ-free plants, the addition of a microbiome from a thermal origin that matched the experimental temperature completely restored plants to their pre-warming growth rates. Metagenome and metatranscriptome analyses revealed that warming altered microbial community structure, including the composition of key cyanobacteria symbionts, in a manner that induced the plant heat shock response, especially the Hsp70 family and jasmonic acid production. The plant heat shock response could be induced even without warming, suggesting that the warming-origin microbiome provided the host plant with thermal preconditioning. Together, our findings show that the microbiome can transmit thermotolerant phenotypes to host plants, providing a valuable strategy for rapidly responding to environmental change.

plant biology↗