Plant neighbor detection and allelochemical response in aboveground

From the report «Plant neighbor detection and allelochemical response are driven by root-secreted signaling chemicals», of Chui-Hua Kong, Song-Zhu Zhang, Yong-Hua Li, Zhi-Chao Xia, Xue-Fang Yang, Scott J. Meiners & Peng Wang, published by Nature.

Plants are capable of detecting and responding to neighboring plants, generating consequences for plant performance and playing important roles in plant coexistence and community assembly. Plant neighbor detection involves both physical and chemical signals, including far-red light reflection, alteration of nutrient availability and plant-released secondary metabolites. These signals trigger complex plant response strategies such as shade avoidance, root foraging, and chemical defense.

Aboveground signaling interactions are well established and mediated by air-borne chemicals including methyl jasmonate, salicylate, benzoate, and indole, as well as ethylene and several volatile terpenes. However, the identity of soil-borne chemicals involved in belowground signaling interactions is largely unknown. In contrast to aboveground signaling chemicals which move freely in air, the transduction of belowground chemicals requires root-soil interactions.
Here, authors experimentally demonstrate neighbor detection and allelopathic responses between wheat and 100 other plant species via belowground signaling.

Wheat can detect both conspecific and heterospecific neighbors and responds by increasing allelochemical production. Furthermore, authors show that (-)-loliolide and jasmonic acid are present in root exudates from a diverse range of species and are able to trigger allelochemical production in wheat.

These findings suggest that root-secreted (-)-loliolide and jasmonic acid are involved in plant neighbor detection and allelochemical response and may be widespread mediators of belowground plant-plant interactions. But, although a generic response to (-)-loliolide was detected, there are likely to be additional signaling mechanisms that could allow species-specific responses. In addition, the ability of the signaling chemical to induce allelopathic responses in plants needs to be explored in other plant systems to test if they respond similarly to allelopathic wheat.