title: Plants can benefit from herbivory: stimulatory effects of sheep saliva on growth of Leymus chinensis.
abstract: BACKGROUND
  Plants and herbivores can evolve beneficial interactions. Growth factors found in animal saliva are probably key factors underlying plant compensatory responses to herbivory. However, there is still a lack of knowledge about how animal saliva interacts with herbivory intensities and how saliva can mobilize photosynthate reserves in damaged plants.
  
  
  RESULTS
  The study examined compensatory responses to herbivory and sheep saliva addition for the grass species Leymus chinensis in three experiments over three years. The first two experiments were conducted in a factorial design with clipping (four levels in 2006 and five in 2007) and two saliva treatment levels. The third experiment examined the mobilization and allocation of stored carbohydrates following clipping and saliva addition treatments. Animal saliva significantly increased tiller number, number of buds, and biomass, however, there was no effect on height. Furthermore, saliva effects were dependent on herbivory intensities, associated with meristem distribution within perennial grass. Animal saliva was found to accelerate hydrolyzation of fructans and accumulation of glucose and fructose.
  
  
  CONCLUSIONS
  The results demonstrated a link between saliva and the mobilization of carbohydrates following herbivory, which is an important advance in our understanding of the evolution of plant responses to herbivory. Herbivory intensity dependence of the effects of saliva stresses the significance of optimal grazing management.
authors.affiliation: Key Laboratory of Vegetation Ecology, Ministry of Education, Institute of Grassland Science, Northeast Normal University, Changchun, Peoples Republic of China.
authors.forename: Jushan
authors.initials: J
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Deli
authors.initials: D
authors.lastname: Wang
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Bonser
authors.forename: Fang
authors.initials: F
authors.lastname: Sun
authors.forename: Yifa
authors.initials: Y
authors.lastname: Zhou
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.forename: Xing
authors.initials: X
authors.lastname: Teng
mesh_terms: D000818:Animals; D018533:Biomass; D050260:Carbohydrate Metabolism; D060434:Herbivory; D006868:Hydrolysis; D018520:Plant Shoots / Q000254:growth & development / Q000378:metabolism; D006109:Poaceae / Q000254:growth & development* / Q000378:metabolism; D012463:Saliva; D012756:Sheep; D013559:Symbiosis