Biology subjects

Vadassery, J.

Publications and source records attributed to Vadassery, J..

6 recordsLinked to original sources

bioRxiv2026

The systemically induced sugar transporter SWEET11 regulates growth-defense trade-offs during Serendipita indica symbiosis in Arabidopsis

Sugar exchange at the root interface is a pivotal process governing the establishment and stability of plant-fungal symbioses. Precise regulation of sugar exchange determines the success of this ecologically significant interaction. Sugar Will Eventually be Exported proteins (SWEETs) constitute a family of regulatory, energy-independent bidirectional sugar transporters that influence plant development, stress resilience, and survival. However, how specific SWEET transporters coordinate systemic carbon allocation and immune regulation during beneficial plant-fungal interactions remains poorly understood. In this study, we examined the role of the systemically induced Arabidopsis sugar transporter SWEET11 during association with the beneficial endophytic fungus Serendipita indica and following treatment with its elicitor, cellotriose (CT). Expression profiling of SWEET family members revealed a rapid and preferential induction of SWEET11 in aerial tissues upon fungal colonization and CT treatment. Loss-of-function of SWEET11 compromises key mutualistic outcomes, including plant growth enhancement, fungal colonization efficiency, penetration ability, carbohydrate distribution, and the regulation of defense-related phytohormones such as jasmonic acid and abscisic acid. Global transcriptome analysis further demonstrated that SWEET11 regulates whole-plant responses by orchestrating genes involved in central metabolism, secondary metabolite production, sesquiterpenoid and triterpenoid pathways, as well as defense signaling and nutrient transport systems. We show that SWEET11 interacts with a stress associated SNF1-related protein kinase (SnRK2.8) and plays a crucial role in enabling fungal establishment while mitigating host defense responses, and supporting plant growth. Our data shows that SWEET11 functions as a shoot-derived sugar exporter that directs carbon toward roots, facilitating sugar unloading to S. indica. This controlled carbon supply allows the fungus to meet its metabolic demands without disrupting host sugar balance, thereby maintaining a stable and well-regulated symbiotic association under immune constraints.

plant biology↗

bioRxiv2025

Arabidopsis SWEET12 regulates sugar allocation and defense responses to sustain beneficial association with Serendipita indica in roots

Carbon availability is a central determinant of beneficial plant-fungal associations, and sugar transporters are key levers of this exchange. SWEETs (SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER) are involved in transporting various kinds of sugars in plants; however, their functional roles in fungal symbiosis are not sufficiently explored. In this study, we investigate the functional relevance of Arabidopsis SWEETs in the interaction with endophytic fungi, Serendipita indica. Transcript profiling of SWEET genes in response to S. indica and its major elicitor, cellotriose, revealed early root-specific induction of SWEET12. Using a SWEET12 loss-of-function mutant, we demonstrate that the absence of SWEET12 disrupts the major outcomes of mutualism including growth promotion, balanced colonization, sugar allocation, and the accumulation of defense phytohormones (JA and SA). Transcriptome profiling further reveals that SWEET12 buffers whole-plant responses by coordinating genes linked to carbohydrate, nitrogen, and lipid metabolism, and by tuning defense signalling and nutrient transporter networks. Our findings indicate that SWEET12 is essential for balancing fungal colonization and host defense, thereby promoting plant growth. SWEET12 does so by acting as sugar valve that meters sugar release to the apoplast, enabling the fungus to access carbon while preserving host sugar homeostasis and immune competence.

plant biology↗

bioRxiv2025

The Ca2+ Channel CYCLIC NUCLEOTIDE GATED CHANNEL13 (CNGC13) regulates systemic wound signalling and immunity against Spodoptera herbivory

Insect herbivory elicits rapid and complex signalling responses in plants, including membrane depolarization, cytosolic Ca2+ elevation and activation of jasmonate-mediated defense pathways in local and systemic leaves. These early events are orchestrated by calcium-permeable channels and regulatory components that generate stimulus-specific cytosolic Ca2+ signatures. However, the molecular mechanisms that generate long-distance Ca2+ propagation and systemic immune activation on herbivory remain poorly defined. Here, we identify CYCLIC NUCLEOTIDE GATED CHANNEL13 (CNGC13) as a novel plasma membrane-localized, phloem-expressed Ca2+ channel that is essential for systemic wound signalling and defense against lepidopteran pest, Spodoptera litura in Arabidopsis thaliana. CNGC13 is rapidly induced by wounding and herbivory, mediates cytosolic Ca2+ influx, and is required for efficient propagation of Ca2+ signals from wounded to distal leaves. Loss of CNGC13 compromises the thioglucosidase-dependent breakdown of aliphatic glucosinolates into aglucones/isothiocyanates within the vascular tissue, which are essential for wounding-induced systemic Ca2+ wave propagation. Consequently, cngc13 mutants display impaired systemic jasmonate accumulation in distal leaves, reduced glucosinolate levels and enhanced herbivore susceptibility. CNGC13 is also required for AtPep-induced Ca2+ elevation and Reactive Oxygen Species (ROS) signalling and interacts with the receptor kinase, PEPR2, implicating it in DAMP-mediated immune responses. Although CNGC13 and CNGC19 function cooperatively in herbivore defense, they do not physically interact, suggesting independent but converging roles. Our study identifies CNGC13 as a vasculature-localized Ca2+-permeable channel that functions downstream of PEPR2 receptor, to sustain systemic signalling, operating in a distinct yet converging pathway alongside known glutamate receptor-like channels during long-distance wound responses. SignificancePlants must detect and respond to insect herbivory rapidly by activating systemic immunity to trigger defense responses. Calcium (Ca2+) signalling plays a central role in this defense network, yet the identities and specific functions of Ca2+ channels involved in long-distance herbivory signalling remain poorly understood. Here, we identify the plasma membrane-localized channel CYCLIC NUCLEOTIDE GATED CHANNEL13 (CNGC13) as a key integrator of mechanical damage perception, ricca factor-mediated systemic signalling, and jasmonate-dependent defense against Spodoptera herbivory in Arabidopsis. CNGC13 facilitates systemic Ca2+ wave propagation, activates jasmonate and glucosinolate biosynthesis, and promotes the perception of damage-associated molecular pattern (DAMP) molecules to confer herbivore resistance. This work uncovers a previously uncharacterized calcium channel that plays a crucial dual role in systemic wound signalling.

plant biology↗

bioRxiv2024

A TORC1-PHR1 signaling axis regulates phosphorus starvation and immunity signaling network in Arabidopsis

The Target of Rapamycin Complex 1 (TORC1) is a crucial eukaryotic kinase that modulates growth in response to nutrient availability. Phosphorus (P) is an essential macronutrient, and its deficiency induces extensive reprogramming of growth and defense strategies in plants. This process involves Phosphate Starvation Response 1 (PHR1), a master regulator of the Phosphate Starvation Response (PSR). In this study, we identify a novel, non-canonical role for TORC1 in regulating P starvation responses in Arabidopsis. We demonstrate that P limitation activates TORC1, leading to the stabilization of PHR1. Inhibition of TORC1 increased sensitivity to P starvation, accompanied by disruption of starvation-induced transcriptional reprogramming. Additionally, our results reveal that the TORC1-PHR1 signaling axis plays a crucial role in reprogramming the expression of genes involved in the plant immune signaling network. This regulation is critical for the symbiotic association with the endophytic fungus Piriformospora indica under P starvation. These findings underscore the significant role of the TORC1-PHR1 module in orchestrating the PSR and highlight the evolutionary adaptation of TORC1 signaling pathways in plants.

plant biology↗

bioRxiv2022

SWEET11 and SWEET12 transporters function in tandem to modulate sugar flux in Arabidopsis: An account of the underlying unique structure-function relationship

Sugar will eventually be exported transporters (SWEETs) have been identified as a unique class of sugar efflux transporters in all biological kingdoms. AtSWEET11 and AtSWEET12 in Arabidopsis act synergistically to perform distinct physiological roles, particularly in apoplasmic phloem loading, seed filling, and sugar level alteration at the site of pathogen infection. Plasma membrane-localized AtSWEET11 and AtSWEET12 transporters exclusively facilitate sucrose transport along the concentration gradient. This article examines the sucrose binding pocket of AtSWEET11 and AtSWEET12 using docking studies, and how they act synergistically in various functions throughout plant development and during abiotic and biotic stresses. Further, we highlight the phylogenetic and the in-silico analyses of AtSWEET11 and AtSWEET12 orthologs from 39 economically important plant species that could provide new platforms for future studies on sugar allocation mechanisms across the different plant families. In-depth understanding of these transporters and their molecular regulatory mechanisms could be harnessed for crop improvement and crop protection.

plant biology↗

bioRxiv2021

Piriformospora indica employs hosts putrescine for growth promotion in plants

Growth promotion by endosymbiont Piriformospora indica has been observed in various plants; however, specific functional metabolites involved in P. indica mediated growth promotion are unknown. A GC-MS based untargeted metabolite analysis was used to identify Solanum lycopersicum metabolites altered during P. indica mediated growth promotion. Metabolomic analysis showed primary metabolites altered and specifically putrescine to be maximally induced in roots during the interaction. P. indica induced putrescine biosynthetic gene SlADC1 in S. lycopersicum and acts via arginine decarboxylase (ADC) mediated pathway. P. indica did not promote growth in Sladc-VIGS (virus induced gene silencing of SlADC gene) lines of S. lycopersicum and when the ADC enzyme was inhibited with an inhibitor, DL--(Difluoromethyl) arginine. In Arabidopsis adc knock-out mutants, P. indica do not promote growth and this response was rescued upon exogenous application of putrescine. Putrescine promoted growth by elevation of auxin (indole-3-acetic acid) and gibberellin (GA4, GA7) levels in S. lycopersicum. Putrescine is also important for P. indica hyphal growth indicating that it is co-adapted by both host and microbe. Hence, we conclude that putrescine is an essential metabolite and its biosynthesis in plants is crucial for P. indica mediated growth promotion and fungal growth.

plant biology↗