Abstract
BackgroundPreviously it has been shown that mechanical wounding, salinity and heat activated a 46 kDa and 44 kDa mitogen-activated protein kinases (MAPKs) in forage related grasses. Forage and turf related grasses are utilized in diverse environments where they are routinely subjected to herbicides and exposed to fire and volatiles after cutting, however very little is known concerning the perception or molecular responses to these different stresses or compounds.ResultsIn the model grass species Lolium temulentum (Lt), a 46 kDa mitogen-activated protein kinase (MAPK) was activated in the leaves within 5 min and a 44 kDa MAPK 15 min after exposure to green leaf volatiles released from grass clippings. When the tips of leaves of Lt plants were scorched by fire, the 46 kDa MAPK and 44 kDa MAPK were rapidly activated within 5 min and 20 min respectively in the treated leaf, and 15 min systemically in an adjacent untreated tiller after exposure to fire. Nonanoic acid (pelargonic acid), a component in herbicides used on grasses, activated a 46 kDa MAPK in the treated leaves within 5 min of exposure and 15 min in systemic tissues. At concentrations normally used in the herbicides, nonanoic acid was found to only weakly activate the 44 kDa MAPK after an hour in treated leaves, but strongly activated it in the systemic tillers 30 min after treatment. Acetic acid, HCl and NaOH also were found to activate these MAPKs in treated tillers.ConclusionThe rapid activation of these MAPKs to a wide range of stress stimuli, suggest that these MAPKs play a role in the perception and response to these stresses and compounds. The activation of the MAPK by green leaf volatiles indicates a role for these compounds in wound signaling in grasses.Electronic supplementary materialThe online version of this article (doi:10.1186/1756-0500-7-807) contains supplementary material, which is available to authorized users.
Highlights
It has been shown that mechanical wounding, salinity and heat activated a 46 kDa and 44 kDa mitogen-activated protein kinases (MAPKs) in forage related grasses
To determine if MAPKs are activated by compounds and conditions that forage and turf grasses are commonly exposed to in the field, three-to-four-week-old plants of the model grass species L. temulentum [54,55] were exposed to herbicides, fire and green leaf volatiles
We have shown that when grass plants are exposed to green leaf volatiles (GLV), fire or Nonanoic acid (NNA) containing herbicides, it resulted in the activation of MAPKs locally and systemically
Summary
It has been shown that mechanical wounding, salinity and heat activated a 46 kDa and 44 kDa mitogen-activated protein kinases (MAPKs) in forage related grasses. Forage and turf related grasses are utilized in diverse environments where they are routinely subjected to herbicides and exposed to fire and volatiles after cutting, very little is known concerning the perception or molecular responses to these different stresses or compounds. The most common abiotic stresses forage and turf related grasses are exposed to in the field are drought, herbicides, fire and grazing/cutting. Much less is known on the molecular responses to the various components in herbicides, to fire and from grazing or cutting in forages and turf related grasses. A cytochrome P450 gene was isolated from rice and expressed in yeast, and the enzyme was shown to catalyze the NADPH-dependent (ω-1)hydroxylation of pelargonic acid, reducing its herbicidal activity, suggesting that it may participate in detoxification of the contact herbicide [19]
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