Detect thy family: Mechanisms, ecology and agricultural aspects of kin recognition in plants

The phenomenon that organisms can distinguish genetically related individuals from strangers (i.e., kin recognition) and exhibit more cooperative behaviours towards their relatives (i.e., positive kin discrimination) has been documented in a wide variety of organisms. However, its occurrence in plants has been considered only recently. Despite the concerns about some methodologies used to document kin recognition, there is sufficient evidence to state that it exists in plants. Effects of kin recognition go well beyond reducing resource competition between related plants and involve interactions with symbionts (e.g., mycorrhizal networks). Kin recognition thus likely has important implications for evolution of plant traits, diversity of plant populations, ecological networks and community structures. Moreover, as kin selection may result in less competitive traits and thus greater population performance, it holds potential promise for crop breeding. Exploration of these evo‑ecological and agricultural implications requires adequate control and measurements of relatedness, sufficient replication at genotypic level and comprehensive measurements of performance/fitness effects of kin discrimination. The primary questions that need to be answered are: when, where and by how much positive kin discrimination improves population performance.Can plant distinguish genetically related individuals from strangers (kin recognition) and exhibit more cooperative behaviour towards their relatives (positive kin discrimination)? Having reviewed the 14 years of research on this issue, we conclude that the answer to this question is yes. Focusing on belowground interactions, we illustrate how this kin recognition involves reduced resource competition between related plants but may also involve interactions with symbionts (e.g., mycorrhizal networks). But the implications of kin recognition for evolution of plant traits, diversity of plant populations, ecological networks and community structures, as well as crop production, though widely suggested to be significant, still need to be explored. Addressing these outstanding questions requires approaches that quantify when, where and by how much positive kin discrimination improves population performance.