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

Jushan Liu,Ying Gao,Ling Wang,Deli Wang,Stephen P. Bonser,Xing Teng,Yifa Zhou,Fang Sun,Gustavo Bonaventure

doi:10.1371/journal.pone.0029259

Jushan Liu, Ying Gao + Show 7 more

Open Access

https://doi.org/10.1371/journal.pone.0029259

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Journal: PloS one	Publication Date: Jan 3, 2012
Citations: 100	License type: CC BY 4.0

Affiliation: Northeast Normal University, UNSW Sydney

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.

Highlights

Herbivory can limit the growth and survivorship of plants, and plants have evolved complex responses to avoid being consumed and/or to survive and flourish after herbivory
Conclusions/Significance: 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
There is some experimental evidence that herbivory may stimulate plant growth and increase plant fitness [5,6,7]

Summary

Introduction

Herbivory can limit the growth and survivorship of plants, and plants have evolved complex responses to avoid being consumed and/or to survive and flourish after herbivory. Plant compensatory growth is ubiquitous in nature and an important adaptive response to herbivory [3,4]. It has been demonstrated that plant response to herbivory is species specific and compensation to herbivory is specific to herbivory type and intensities [8,9,10,11,12]. Studies are required to establish the environmental cues plants use to initiate a compensation response. Animal saliva may be an important cue plants use to stimulate growth and initiate compensation [13,14,15]. Growth factors found in animal saliva are probably key factors underlying plant compensatory responses to herbivory. 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

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