Transcriptome Analysis of Wounding in the Model Grass Lolium temulentum.

James E Dombrowski,Vicky Hollenbeck,Ruth C Martin,Brent A Kronmiller

doi:10.3390/plants9060780

Abstract

For forage and turf grasses, wounding is a predominant stress that often results in extensive loss of vegetative tissues followed by rapid regrowth. Currently, little is known concerning the perception, signaling, or molecular responses associated with wound stress in forage- and turf-related grasses. A transcriptome analysis of Lolium temulentum plants subjected to severe wounding revealed 9413 upregulated and 7704 downregulated, distinct, differentially expressed genes (DEGs). Categories related to signaling, transcription, and response to stimuli were enriched in the upregulated DEGs. Specifically, sequences annotated as enzymes involved in hormone biosynthesis/action and cell wall modifications, mitogen-activated protein kinases, WRKY transcription factors, proteinase inhibitors, and pathogen defense-related DEGs were identified. Surprisingly, DEGs related to heat shock and chaperones were more prevalent in the downregulated DEGs when compared with the upregulated DEGs. This wound transcriptome analysis is the first step in identifying the molecular components and pathways used by grasses in response to wounding. The information gained from the analysis will provide a valuable molecular resource that will be used to develop approaches that can improve the recovery, regrowth, and long-term fitness of forage and turf grasses before/after cutting or grazing.

Highlights

Grasses are subjected to multiple biotic and abiotic stresses throughout their life cycle
Grasses produce signals that rapidly activate mitogen-activated protein kinases (MAPKs), in the damaged tiller, and in adjacent tillers within three minutes of wounding (Figure 6A) [66]. These MAPK signaling proteins could be activated by intra-plant signals such as reactive oxygen species, hydraulic, electrical, and/or phytohormone based signals or by wound-released airborne green leaf volatiles (GLVs) chemical signals
Intra-plant-based signaling molecules would have to travel down the pseudostem of the wounded tiller through the dense root crown and back up into the adjacent unwounded tillers to generate a response in the adjacent tiller (Figure 6A, yellow arrows)

Summary

Introduction

Grasses are subjected to multiple biotic and abiotic stresses throughout their life cycle. They must be able to sense the different types of stress and respond appropriately to alter cellular, metabolic, and physiological processes to adapt and survive these stresses. Damage or loss of plant tissue occurs when plants are crushed by treading, grazing, feeding insects, or cutting. Most of these wound stresses result in extensive loss of vegetative tissues and rapid regrowth. The molecular characterization of the wound stress response has been most extensively carried out in dicotyledonous plant systems [1,2,3,4]; it has not been as well characterized in monocots

Methods

Results

Conclusion