Plants Can Benefit from Herbivory: Stimulatory Effects of Sheep Saliva on Growth of Leymus chinensis

Abstract

BackgroundPlants 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.Methodology/Principal FindingsThe 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/SignificanceThe 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.

Saliva proteomics as an emerging, non-invasive tool to study livestock physiology, nutrition and diseases

“…On the other hand, animal salivary secretions may additionally influence growth and development of certain food plants [69] -a both surprising and exciting hypothesis that has regained scientific interest and produced first supporting data in goats, cattle and sheep in recent years [70][71][72][73]. Salivary growth factors, such as EGF, NGF or TGF, are discussed as the most probable enhancers of plant re-growth [73] and because of their peptide nature they are accessible by proteomic studies.…”

“…Salivary growth factors, such as EGF, NGF or TGF, are discussed as the most probable enhancers of plant re-growth [73] and because of their peptide nature they are accessible by proteomic studies. In a recent study it was found that animal saliva stimulated growth of perennial grasses, accelerating mobilisation of carbohydrates, enhancing buds tillers and consequently increasing biomass [73]. In another study that employed a proteomics approach on rice seedlings, ovine saliva deposition caused the rice to develop a basal defense, i.e.…”

Leaf turnover and herbivory in the tall tussock grass Festuca orthophylla in the Andean Altiplano

“…However, both Poa liguralis and Kobresia myosuroides compensated for the shorter leaves, by producing more leaves per tiller. Accordingly, increasing clipping intensity in Leymus chinensis resulted in decreasing final shoot length, and tillering decreased only in 100 %-clipped individuals in one of two studied years, and resulted in a generally lower biomass accumulation in clipped plants (Liu et al 2012).…”

Revegetation of artificial grassland improve soil organic and inorganic carbon and water of abandoned mine

“…Socher et al (2013) also found that mowing at intermediate levels generally enhanced plant species richness. Additional under proper stocking densities, grazing promoted plant species richness and plant productivity (Liu et al, 2012;Socher et al, 2013). In order to make full use of limited grassland resources, total porosity increased, and soil particle size distribution also changed after nine years of restoration.…”