Abstract
Identity recognition systems allow plants to tailor competitive phenotypes in response to the genetic relatedness of neighbours. There is limited evidence for the existence of recognition systems in crop species and whether they operate at a level that would allow for identification of different degrees of relatedness. Here, we test the responses of commercial soya bean cultivars to neighbours of varying genetic relatedness consisting of other commercial cultivars (intraspecific), its wild progenitor Glycine soja, and another leguminous species Phaseolus vulgaris (interspecific). We found, for the first time to our knowledge, that a commercial soya bean cultivar, OAC Wallace, showed identity recognition responses to neighbours at different levels of genetic relatedness. OAC Wallace showed no response when grown with other commercial soya bean cultivars (intra-specific neighbours), showed increased allocation to leaves compared with stems with wild soya beans (highly related wild progenitor species), and increased allocation to leaves compared with stems and roots with white beans (interspecific neighbours). Wild soya bean also responded to identity recognition but these responses involved changes in biomass allocation towards stems instead of leaves suggesting that identity recognition responses are species-specific and consistent with the ecology of the species. In conclusion, elucidating identity recognition in crops may provide further knowledge into mechanisms of crop competition and the relationship between crop density and yield.
Highlights
Competition is one of the key processes that dominate plant–plant interactions [1,2,3,4]
The commercial cultivar OAC Wallace increased allocation to leaves compared with stems and increased total plant biomass when growing with neighbours of its ancestral species, wild soya bean
We examined the responses of commercial soya bean plants to the presence of neighbours of varying genetic relatedness
Summary
Competition is one of the key processes that dominate plant–plant interactions [1,2,3,4]. Most plants display some degree of plasticity. In the production of phenotypes involved in maximizing their competitive ability [5]. This phenotypic 2 plasticity to competition in plants can be considered analogous to competitive behaviour in animals and is, among other factors, highly dependent on the degree of genetic relatedness of neighbours [6,7,8,9]. The more related two individuals are, the less they will benefit from producing competitive phenotypes that can harm their neighbours because they share genetic material. Kin selection theory states that any trait or behaviour that benefits a relative will be selected as long as the benefit to the relative is greater than the cost to the organism displaying the trait or behaviour [10]
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