Award details

Spatial regulation of rice D14L for pre-symbiotic perception of beneficial fungi

Reference	BB/P003176/1
Principal Investigator / Supervisor	Dr Emma Wallington
Co-Investigators / Co-Supervisors
Institution	National Inst of Agricultural Botany
Department	Centre for Research
Funding type	Research
Value (£)	196,755
Status	Completed
Type	Research Grant
Start date	15/11/2016
End date	12/05/2020
Duration	42 months

Abstract

We follow a multidisciplinary approach to maximize the resolution of our analysis by exploiting the resources available in rice. Rice offers a high attractive plant system for an integrated combination of genetic, transcriptomic, proteomic and cell biological approaches, having a well annotated genome, efficient transformation protocols and its roots being amenable to confocal microscopy. With the proposal aiming at the elucidation of the spatial regulation of D14L signaling activities across root tissues and subcellular compartments the technical workplan largely builds on Agrobacterium-mediated plant transformation, confocal microscopy, and also RNA seq and LC-MS/MS as central methodologies. Efficient protocols for the transformation of cereal crops have been established in the team of the joint-applicant Emma Wallington (EW) who routinely deliver a high number of transformants with, in rice, at least 40% of lines carrying single copy T-DNA integrations. We base all our constructs for plant transformation on the GAL4-VP16/UAS transactivation system to increase transgene transcription (and thereby sensitivity) without losing cell- or treatment specificity. Multiphoton and lightsheet confocal microscopy will enable the deep root tissue analysis of fluorescent protein accumulation and where desired in real time. These microscopes are used on a daily basis to monitor fluorescent proteins in rice roots by another PDRA in my group (Ronelle Roth). The proposed work is thus feasible in rice. RNAseq and LC-MS/MS analyses will be performed on tissue from the same individuals allowing for the direct comparison where desired. These efforts follow established protocols at the respective platforms at the University of Cambridge and enable the quantitative and qualitative estimate of transcripts and proteins.

Summary

A key event in the evolution of higher life on earth is the transition of plant life from water to land. To explore the terrestrial environment plants had to develop strategies for the acquisition of soil nutrients with initially primitive root precursors. Ever since, plants have lived in symbioses with nutrient-delivering beneficial fungi. Today, the arbuscular mycorrhizal (AM) symbiosis is the most commonly occurring beneficial plant-fungal interaction on earth, contributing to plant fitness, plant biodiversity and global nutrient cycles. Yet, we are only beginning to unveil the molecular processes leading to mutual recognition in the rhizosphere. Colonization of plant roots by AM fungi requires the reciprocal exchange of diffusible molecules before fungal attachment to the root surface occurs. Chitin-related compounds secreted by AM fungi trigger plant molecular and developmental responses. Receptor kinase proteins detect these fungal molecules in the extracellular space and initiate a cellular reprogramming leading to a change in root system development. Mutational analyses showed that these receptor kinases are indeed required for development of AM symbioses but appear not to be essential. How plants perceive these prevalent beneficial fungi has therefore still been an unanswered question. My group has found that an intracellular alpha/beta hydrolase type protein, called DWARF 14 LIKE (D14L) is crucial for fungal perception by rice. In our recent Science publication we report our finding that the deletion of this gene from the rice genome rendered the plant unable to sense the fungus. Interestingly, the protein has additional roles in detecting the smoke constituent karrikin and in mediating developmental responses to light. It is evolutionarily conserved and may have therefore served similar functions in early terrestrial plants. The recognition of the fungus by the root and the subsequent establishment of primary contact involves distinct root tissue andcell types. The precise coordination of signaling events in space and time is thus essential for the successful development of AM symbioses. With this proposal we wish to determine where in the root tissue (relative to the approaching fungus) the protein needs to be present, and by magnifying onto the subcellular level, where within the cell the protein functions in initiating signal transduction and what are the respective 'molecular translations' of signalling. Given the central role of D14L in a variety of responses to environmental stimuli elucidating the tissue/cell type contributing to the signaling is vital for understanding coordination and specificity of this general and ancient plant symbiosis.

Impact Summary

The proposed work will have extensive academic, economic, and societal impacts. The major beneficiaries of this work will be: (i) Scientists, who will derive advantage from increased basic knowledge of plant root interactions with the rhizosphere environment, namely nutrient-delivering fungi. These beneficiaries will experience multidisciplinary working in molecular biology, genetics, cell biology, and cutting edge imaging to bridge the knowledge-gap concerning the earliest stage in plant perception of mutualistic soil fungi. (ii) Farmers, who will benefit through advice on application of beneficial fungi targeted to the needs of specific crop varieties, and through a broader general appreciation of the complexity of crop-symbiont interactions in the long term. (iii) Crop breeders, who will benefit from new knowledge to enable the selection of varieties adapted to maximize responsiveness to the mineral-providing root symbiosis. (iv) Industry, who will take advantage from shared knowledge to develop strategies on the basis of the new findings. (v) Policy makers, particularly in rice-growing areas, who will benefit from shared knowledge which can be used to develop legislation limiting/regulating sustainable fertilization and (vi) Wider society, who will ultimately benefit through reduced detrimental impacts on environment by reduction in agro-chemical inputs in food production and increased food security. This proposal will provide a new insight into the mechanisms of pre-symbiotic root signalling which will be invaluable in designing strategies for accelerated establishment of the symbiosis, informing breeding efforts towards crop varieties with optimized symbiotic responsiveness. Rice is a staple food for more than half of the human population and is therefore central for food security plus a target for the design of sustainable strategies to increase crop yield. Rice also serves as the primary model for other cereals such as wheat, barley and maize, and lessons learned from rice have the potential to guide research and breeding programmes. We will communicate our findings to the scientific community through publication in peer-reviewed journals. Farmers and industry stakeholders will be informed through events organised by the Agri-Tech East cluster, Cambridge Partnership for Plant Science and NIAB Open Days and articles in the NIAB journal, Landmark. We will also initiate public demonstrations of the project to publicise our work, engaging in presentations at events such as the annual Cambridge Science festival, the Festival of Plants at the Botanic Garden and the National Biology Week.

Committee	Research Committee B (Plants, microbes, food & sustainability)
Research Topics	Crop Science, Microbiology, Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

Associated awards:

BB/P003419/1 Spatial regulation of rice D14L for pre-symbiotic perception of beneficial fungi

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