The plant science domain aims at studying the adaptation of plants to their environment, with applications ranging from improving crop yield or resistance to environmental conditions, to managing forest ecossystems.
Data integration and reuse are imperative in this domain, as it relies on understanding the play between genotype and environment to produce a phenotype, and therefore requires integrating phenotyping experiments and genomic assays made on the same plant material, with geo-climatic data. Moreover, cross-species comparisons are often necessary to understand the mechanisms behind phenotypic traits, especially at the genotypic level, due to the gap in genomic knowledge between well-studied plant species (namely Arabidopsis) and newly sequenced ones. Yet, in few domains is data integration so challenging.
The challenges to data integration stem from the multiple levels of heterogeneity in this domain. It encompasses a variety of species, ranging from model organisms, to crop species, to wild plants such as forest trees. These often need to be detailed at infra-specific levels (e.g. subspecies, variety), but naming at these levels sometimes lacks consensus. Studies can take place in a diversity of settings including indoor (e.g. growth chamber, greenhouse) and outdoor settings (e.g. cultivated field, forest) which differ fundamentally on the requirements and manner of characterizing the environment. Phenotypic data can be collected manually or automatically (by sensors and drones), and be very diverse in nature, spanning physical measurements, the results of biochemical assays, and images. Thus the extension and depth of metadata required to describe a plant experiment in a FAIR-compliant way is very demanding for researchers.
Another particularity of this domain is the absence of central deposition databases for plant phenotyping data. Whereas datasets from plant omics experiments are typically deposited in global deposition databases for that type of experiment, those from phenotyping experiments remain in institutional or at best national repositories. This raises challenges to finding and accessing plant phenotyping data, as well as interconnecting all datasets produced in projects that encompass molecular studies and phenotyping experiments.
Plant phenotyping metadata management
To ensure compliance with the FAIR principles in plant phenotyping datasets, it is highly recommended that metadata collection is contemplated from the start of the experiment and that the working environment facilitates (meta)data collection, storage, and validation throughout the project, up to the publication.
Detailed metadata needs to be captured on a number of aspects. One of the most critical is the description of the biological materials used in the study—the plant varieties and, when applicable, the seed lots or the parent plants—as they are the key to integrating omics and phenotyping datasets. Particularly in field studies, it is equally critical to record the geographical coordinates and time of the experiment, for linkage with geo-climatic data. In growth chamber or greenhouse studies, the environmental conditions that were fixed should be described in detail.
- Is your plant material provided by a Genebank or derived from a material provided by a Genebank?
- Have you documented your phenotyping assays (trait, method, units) both for direct measures and computed data?
- Is there an existing Crop Ontology for the species you experiment and does it describe your assay?
- Do you have your own system to collect data and is it compliant with the MIAPPE standard?
- The metadata standard applicable to plant phenotyping experiments is MIAPPE.
- It contains a section dedicated to the identification of plant biological materials that follows the general standard for the identification of plant genetic resources, The Multi-Crop Passport Descriptors (MCPD).
- It is also possible to describe samples that were collected from the experimented plants for specific phenotyping assays.
- For woody plants, particularly those in forest settings, it is common to use GPS coordinates as a unique identifier for plant material.
- There is a section to describe the phenotyping assays based on the Crop Ontology recommendations.
- There is section describing the experiment itself (greenhouse, field, etc…) and it is advisable to collect its geographical coordinates and time of experiment for linkage with geo-climatic data.
- Tools and resources for data collection and management:
- The ISA-Tools also include a configuration for MIAPPE and can be used both for filling-in metadata and for validating.
- SEEK and Dataverse are free data management platforms for which MIAPPE templates are in development.
- COPO is a data management platform specific for the plant sciences.
- FAIRsharing is a manually curated registry of reporting guidelines, vocabularies, identifier scheme, models, formats, repositories, knowledgebases, and data policies that includes many resources relevant for managing plant phenotyping data.
- Validation of MIAPPE compliance can be done via ISA-Tools or upon data deposition in a BrAPI-compliant repository (Breeding API, BrAPI.
Plant phenotyoping data sharing and deposition
Sharing, deposition and publication of plant phenotyping data can be challenging, given that there is no global centralized archive for this type of data. Research projects often involve multiple partners, some of which collect data into their own (institutional) data management platforms, whereas others collect data manually into excel spreadsheets. For researchers, it is critical that the datasets collected in different media by the partners in a research project (or across different collaborative projects) can be shared in a way that enables their integration, both for collective analysis and for deposition into a single repository. For managers of plant phenotyping data repositories that support a project or institution, it is essential to ensure that the uptake of data is easy and includes a step of metadata validation upon intake.
- Are you exchanging data with individual researchers?
- In what media are data being collected?
- Are the data described in a MIAPPE-compliant manner?
- Are you exchanging data management platforms?
- Do these platforms implement BrAPI?
- If not, are they MIAPPE-compliant and do they enable automated data exchange?
- If you or your partners collect data manually, it is critical to adopt a spreadsheet template that is compatible with the structure of the database that will be used for data deposition.
- If you or your partners collect data into data management platforms:
- If it implements BrAPI, you can exchange data using BrAPI calls.
- If it doesn’t implement BrAPI, the simplest solution would be to export data into the MIAPPE spreadsheet template, or whichever other template you defined for manual collection.
- For data deposition, it is highly recommended that you opt for one of the many repositories that implement BrAPI, as this enables both validation and findability, through the ELIXIR plant data discovery service, FAIDARE.
Integrating plant phenotypic and molecular data
Plant phenoptying experiments require integrating genomic and phenotypic data of the plants with data about their environment. While phenotypic and environmental data are typically stored together in phenotyping databases, genomic and other types of molecular data are deposited in international deposition databases for that type of data, typically within the INSDC global consortium. It can be challenging to integrate phenotypic and molecular data even within a single project, particularly if the project involves studying a panel of genetic resources in different conditions. To do so, it is paramount to keep the link between the plant material in the field, the samples extracted from them (e.g. at different development stages), and the results of omics experiments (e.g. transcriptomics, metabolomics) performed on those samples, across all datasets that will be generated and published. Even more challenging is integrating phenoptypic and molecular data about the same plants across different experiments.
Integrating phenotyping and molecular data, both within and between studies, hinges entirely on precise identification of the plant material under study (down to the variety, or even the seed lot), as well as of the samples that are collected from these plants.
- Are you working with established plant varieties, namely of crop plants?
- Can you trace their provenance to a genebank and/or are they identified in a germplasm database?
- Are working with crosses of established plant varieties?
- Can you trace the geneology of the crosses to plant varieties from a genebank or identified in a germplasm database?
- The identification and description of plant materials should comply with the standard for the identification of plant genetic resources, The Multi-Crop Passport Descriptors (MCPD).
- If your plant materials that cannot be traced to an existing genebank or germplasm database, you should be describe them in accordance with the MCPD in as much detail as possible.
- If your plant materials can be traced to an existing genebank or germplasm database, you need only complement the MCPD information already published in the genebank or germplasm database.
- For wild trees, or plant materials derived from them, precise identification often requires the GPS coordinates of the tree.
- For identifying your plant material in a genebank or germplasm database, you can consult the European Cooperative Programme for Plant Genetic Resources (ECPGR), which includes a central germplasm database and a catalogue of relevant external databases.
- Another key database for identifying plant material is the European Search Catalogue for Plant Genetic Resources (EURISCO), which provides information about more than 2 million accessions of crop plants and their wild relatives, from hundreds of institutes in 43 member countries.
- For identifying samples from which molecular data was produced, you should use the Biosamples database, even when it is not required by the database in which you will deposit the molecular data.
- When detailing your sample in Biosamples, it is critical that you provide either a global identifier to your plant materials in a genebank or germplasm database, or a precise description of the plant materials in accordance with the MCPD.
- It is also recommended that you provide permanent access to a description of the project or study, that contains links to all the data, molecular or phenotypic. The Biostudies database is recommended for this purpose.
Relevant tools and resources
|Tool or resource||Description||Tags||Registry|
|Biosamples||BioSamples stores and supplies descriptions and metadata about biological samples used in research and development by academia and industry.||metadata plants|
|Biostudies||The BioStudies database holds descriptions of biological studies and links to data from these studies in other databases.||metadata plants|
|BrAPI||Specification for a standard API for plant data: plant material, plant phenotyping data||IT support plants|
|COPO||Portal for scientists to broker more easily rich metadata alongside data to public repos.||metadata researcher plants|
|Crop Ontology||The Crop Ontology compiles concepts to curate phenotyping assays on crop plants, including anatomy, structure and phenotype.||researcher data manager IT support plants|
|e!DAL-PGP||Plant Genomics and Phenomics Research Data Repository||plants researcher data manager IT support|
|ECPGR||Hub for the identification of plant genetic resources in Europe||plants researcher data manager|
|EURISCO||European Search Catalogue for Plant Genetic Resources||plants researcher data manager|
|FAIDARE||FAIDARE is a tool allowing to search data across dinstinct databases that implemented BrAPI.||researcher data manager plants|
|GnpIS||A multispecies integrative information system dedicated to plant and fungi pests. It allows researchers to access genetic, phenotypic and genomic data. It is used by both large international projects and the French National Research Institute for Agriculture, Food and Environment.||plants|
|MCPD||The Multi-Crop Passport Descriptor is the metadata standard for plant genetic resources maintained ex situ by genbanks.||metadata researcher IT support policy officer plants|
|MCPD||The Multi-crop Passport Descriptors are an international standard to facilitate germplasm passport information exchange||metadata plants|
|MIAPPE||Minimum Information About a Plant Phenotyping Experiment||metadata researcher data manager plants|