The Mechanisms Of Inductive Effects Of Heterogenous Plants On The Production Of Allelochemical In Wheat

Chemical recognition and response between plant individuals are critical topics of research on plant behaviors, the main characteristics of which are described by the variation of secondary metabolites in plants. Investigating the mechanisms of recognition and response between plants will contribute to the understanding of interspecific interaction. In this study, the mechanisms of inductive effects of heterogenous plants on the production of allelochemical in wheat were investigated.The results showed that:(1) The proportions between wheat and its coexisting heterogenous plants were1:1,3:3,5:5,10:10,15:15and20:20. The production of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) in wheat were induced by heterogenous plants, and the inductive effects varied with the density levels. The largest increase was observed at the proportion of5:5. At the same density level, the inductive effects varied with plants species. Wheat suppressed the growth of neighboring heterogenous plants, the largest inhibition rate was observed at the proportion of5:5. The inhibition rate then decreased as densities increased.(2) Keep wheat at the density of5plants/pot, the proportions between wheat and its coexisting heterogenous plants were5:1,5:2,5:3,5:4,5:5,5:6,5:7,5:8,5:9and5:10. The inductive effects of the coexisting plants on the production of DIMBOA in wheat were closely related to the plants species. As densities of coexisting plants increased the concentration of DIMBOA increased at first and then decreased. The largest increase was observed at the density of5plants/pot for the coexisting plants including Digitaria sanguinalis, Abutilon theophrasti, Elensine indica, Glycine max, and Raphanus sativus. While for the coexisting plants Echinochloa crusgalli, Amaranthus retroflexus, Aegilops tauschii, Avena fatua and Alopecurus japonicus, the largest increase was observed at the density of8plants/pot.(3) Seeding time of coexisting heterogenous plants showed significant influence on the production of DIMBOA in wheat and the biomass. The concentration of DIMBOA from high to low was:sowing coexisting plants early> sowing coexisting plants and wheat at the same time> sowing coexisting plants late. The wheat biomass from high to low was:sowing coexisting plants early<sowing coexisting plants and wheat at the same time<sowing coexisting plants late. When the heterogenous plants and wheat were planted with the treatments of root contact and root separation (30um nylon mesh,0.45μm nylon mesh), wheat could recognize the coexisting heterogenous plants and make a biochemical response to them. When the roots of the heterogenous plants and wheat were separated completely (plastic film), no inductive effects of the production of DIMBOA in wheat were observed. (4) The production of DIMBOA in wheat could be induced by the root exudates of the coexisting plants, while the inductive effects were significantly correlated with the addition time and concentration of the exudates. High concentration of root exudates increased the DIMBOA concentration, and the significant increase occurred at6h and at9h of incubation.The results suggested that wheat could recognize the coexisting heterogenous plants, and make a plastic chemical response by the variation of allelochemical DIMBOA in wheat. Wheat recognized and response to the coexisting heterogenous plants through information chemicals in the soil released from the roots of the coexisting plants. The inductive effects of heterogenous plants on the production of DIMBOA in wheat varied with the density levels and species of coexisting plants.