Communication between Two Lactuca Species

There is increasing evidence of plant communication and behavior. We examine how two Lactuca species, L. sativa andL. serriola, communicate with themselves and one another via root exudates. We exposed both species to their own, to the same species, and to the other species root exudates. We then measured the length of their primary root as a proxy for competitive effort. L. serriola produced longer roots when exposed to its own exudates relative to when exposed to L. sativa’s. In contrast, L. sativa produced shorter roots when exposed to its own root exudates. These results indicate kin recognition in these species. Further, the results show that L. sativa, a domesticated species, shares resources well with conspecifics. In contrast, L. serriola, a sparsely distributed species, is more competitive with conspecifics than with other species. We argue that artificial selection and domestication of L. sativa, from its progenitor L. serriola, modify how the species interprets and respond to exudate cues from neighboring plants.

Language of plants: Where is the word?

Plants emit biogenic volatile organic compounds（BVOCs） causing transcriptomic, metabolomic and behavioral responses in receiver organisms. Volatiles involved in such responses are often called ＂plant language＂. Arthropods having sensitive chemoreceptors can recognize language released by plants. Insect herbivores, pollinators and natural enemies respond to composition of volatiles from plants with specialized receptors responding to different types of compounds. In contrast, the mechanism of how plants＂hear＂ volatiles has remained obscured. In a plant-plant communication, several individually emitted compounds are known to prime defense response in receiver plants with a specific manner according to the chemical structure of each volatile compound. Further, composition and ratio of volatile compounds in the plant-released plume is important in plantinsect and plant-plant interactions mediated by plant volatiles. Studies on volatile-mediated plant-plant signaling indicate that the signaling distances are rather short, usually not longer than one meter. Volatile communication from plants to insects such as pollinators could be across distances of hundreds of meters. As many of the herbivore induced VOCs have rather short atmospheric life times, we suggest that in long-distant communications with plant volatiles,reaction products in the original emitted compounds may have additional information value of the distance to emission source together with the original plant-emitted compounds.