As climate change accelerates, there will be increasing droughts and temperature stresses. One solution to help plants is to cross-breed them with their wild relatives to introduce new genes. However, in an article in Plants People Planet, Makenzie Mabry and colleagues argue that we should also look at the bad boys of agriculture, feral crops. Feral crops are plants that have escaped cultivation and continue to thrive without human intervention. Feral plants can also be a problem for farmers, acting as weeds. The authors say that the traits that make feral crops undesirable neighbours, outcompeting crops for water and nutrients, show that they also offer a valuable source of genetic diversity, potentially enhancing the resilience of their cultivated counterparts.
While the study of feral crops – populations that have established themselves beyond cultivation – has gained some momentum in recent years, it remains an under-researched area. Some scientists emphasise the negative consequences of feralisation. Mabry and colleagues give the example of feral rice which, they say, has a bigger impact on reducing rice yield than the leading rice pathogen. They also highlight work on how feral crops might be a source of genes for domesticated crops. But they find something is missing. They write:
There have been several calls to examine ferality in a more systematic and comparative manner. Gering et al. (2019) argue for a concerted effort to compare feral plants with their domesticated relatives and wild populations, as well as feral plants across populations or species. Little is known, for example, about how the effects of artificial selection on crops continue to influence descendent feral populations.Mabry et al. 2023.
Of particular interest to them is a lack of communication between feral crop researchers. The authors conducted a literature survey and found that feral crop researchers tended to focus on a specific feral crop and its domesticated counterpart. There were relatively few connections between studies of different feral crops.
What is driving the interest in feralisation now? A key spur has been a colloquium titled “Darwins’ reversals: What we now know about Feralization and Crop Wild Relatives” held at the BOTANY 2021 conference. The researchers identified seven categories of questions that span both basic and applied research, providing a foundation for future studies. These categories include:
- Definitions and drivers of ferality: Clarifying the terminology and factors that contribute to the emergence of feral crops.
- Genetic architecture and pathways: Investigating the genetic changes that occur during feralisation and how these adaptations may benefit cultivated crops.
- Evolutionary history and biogeography: Examining the origins and geographical distribution of feral crops, as well as their relationships with their cultivated relatives.
- Agronomy and breeding: Assessing the potential of feral crops for improving crop resilience and productivity through targeted breeding programs.
- Fundamental and applied ecology: Exploring the ecological interactions between feral crops, cultivated crops, and other species, as well as the implications for agricultural practices and biodiversity conservation.
- Collecting and conservation: Developing strategies for collecting, preserving, and utilising feral crop genetic resources for crop improvement and food security.
- Taxonomy and best practices: Establishing standardised methods for classifying and studying feral crops, as well as sharing data and findings among researchers.
As the world grapples with the challenges posed by climate change, the untapped potential of feral crops may prove to be a valuable resource for bolstering food security. By addressing these questions and fostering international collaboration, researchers hope to unlock the secrets of feralisation and harness the power of feral crops to better feed our planet.
On a slightly grimmer note, as ecosystems break down, a better understanding of feralisation could also help prepare us for the challenges farmers will face over the next century. It would also help explain how feral crops will impact biodiversity in neighbouring habitats.
To get this knowledge, Mabry and colleagues conclude that we need to connect the traditionally separated fields of ecology, agronomy, and evolutionary biology. This way, we can uncover the potential of feral crops and improve our understanding of this largely unexplored human-caused phenomenon.
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Mabry, M.E., Bagavathiannan, M.V., Bullock, J.M., Wang, H., Caicedo, A.L., Dabney, C.J., Drummond, E.B.M., Frawley, E., Gressel, J., Husband, B.C., Lawton-Rauh, A., Maggioni, L., Olsen, K.M., Pandolfo, C., Pires, J.C., Pisias, M.T., Razifard, H., Soltis, D.E., Soltis, P.S., Tillería, S., Ureta, S., Warschefsky, E. and McAlvay, A.C. (2023) “Building a feral future: Open questions in crop ferality,” Plants, People, Planet. Available at: https://doi.org/10.1002/ppp3.10367.