The social life of plants

Most people would not think of plants as social organisms. But sociality simply means that individuals live and interact in groups. Plants are certainly group-living, and they compete with their neighbours for vital resources. Moreover, neighbouring plants would often benefit by cooperating, or competing less. In fact, the key food crops of the world have been bred to be dwarfed, allowing plants to spend less energy on being tall competitors and more on making grains. In agriculture, dwarfism is particularly useful in genetically uniform crops that exclude taller competitors. Similarly, in nature, cooperative plants could be favoured when neighbours share genes for a cooperative trait.

The aim of my research is to create a two-way dialogue between agriculture and evolutionary biology. On the one hand, we can use our knowledge of how cooperation evolves in nature to harness even more cooperation in agriculture. On the other hand,we can use what we know from agriculture to look for cooperation among plants in nature. 

My recent work has examined the potential for cooperative traits in Arabidopsis thaliana. Arabidopsis is an excellent study organism because of its genetic tools for examining variation in plant growth. I took advantage of a synthetic population that mixes up the variation from 19 different A. thalianagenotypes in nature.

With collaborators at Aberystwyth University, I asked: what traits maximize reproduction when plants grow alone versus when they grow together, in genetically uniform groups? We found that plants growing alone do best when they have genes for being large; in contrast, plants in groups do best with genes for being small. These results suggest a fundamental trade-off in nature: traits/genes that promote individual self-interest are not always best for the group.

I am building on these results in two ways. First, with collaborators at the National Institute of Agricultural Botany (NIAB), I am performing a scaled-up version of my recent Arabidopsis work, using winter wheat in an agricultural setting. We are aiming to find novel cooperative traits/genes that have been missed by past breeding. Second, to follow up on the benefits of being small, I am studying naturally-occurring Arabidopsis genotypes that carry the same dwarfing mutations as modern crops. Ultimately, I want to know if dwarfism is favoured by natural selection for the same role it plays in agriculture—that is, as a cooperative trait that promotes the collective productivity of groups.