Limits...
Fatty acid-amino acid conjugates are essential for systemic activation of salicylic acid-induced protein kinase and accumulation of jasmonic acid in Nicotiana attenuata.

Hettenhausen C, Heinrich M, Baldwin IT, Wu J - BMC Plant Biol. (2014)

Bottom Line: Previous studies mainly focused on individual responses and a limited number of systemic leaves, and more research is needed for a better understanding of how different plant parts respond to herbivory.In contrast to the activation of SIPK and elevation of JA in specific systemic leaves, increases in the activity of an important anti-herbivore defense, trypsin proteinase inhibitor (TPI), were observed in all systemic leaves after simulated herbivory, suggesting that systemic TPI induction does not require SIPK activation and JA increases.Leaf ablation experiments demonstrated that within 10 minutes after simulated herbivory, a signal (or signals) was produced and transported out of the treated leaves, and subsequently activated systemic responses.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Herbivory induces the activation of mitogen-activated protein kinases (MAPKs), the accumulation of jasmonates and defensive metabolites in damaged leaves and in distal undamaged leaves. Previous studies mainly focused on individual responses and a limited number of systemic leaves, and more research is needed for a better understanding of how different plant parts respond to herbivory. In the wild tobacco Nicotiana attenuata, FACs (fatty acid-amino acid conjugates) in Manduca sexta oral secretions (OS) are the major elicitors that induce herbivory-specific signaling but their role in systemic signaling is largely unknown.

Results: Here, we show that simulated herbivory (adding M. sexta OS to fresh wounds) dramatically increased SIPK (salicylic acid-induced protein kinase) activity and jasmonic acid (JA) levels in damaged leaves and in certain (but not all) undamaged systemic leaves, whereas wounding alone had no detectable systemic effects; importantly, FACs and wounding are both required for activating these systemic responses. In contrast to the activation of SIPK and elevation of JA in specific systemic leaves, increases in the activity of an important anti-herbivore defense, trypsin proteinase inhibitor (TPI), were observed in all systemic leaves after simulated herbivory, suggesting that systemic TPI induction does not require SIPK activation and JA increases. Leaf ablation experiments demonstrated that within 10 minutes after simulated herbivory, a signal (or signals) was produced and transported out of the treated leaves, and subsequently activated systemic responses.

Conclusions: Our results reveal that N. attenuata specifically recognizes herbivore-derived FACs in damaged leaves and rapidly send out a long-distance signal to phylotactically connected leaves to activate MAPK and JA signaling, and we propose that FACs that penetrated into wounds rapidly induce the production of another long-distance signal(s) which travels to all systemic leaves and activates TPI defense.

Show MeSH
W + OS-induced JA accumulation in local and systemic leaves. The leaves undergoing source-sink transition, designated as the leaves 0, were wounded with a pattern wheel and 20 μl of 1/5 diluted M. sexta OS were immediately applied to wounds (W + OS). Samples were harvested at indicated times, and their JA and JA-Ile contents were analyzed. a Numbering of the leaf positions in a bolting N. attenuata plant and the additive angular distances assuming 3/8 phyllotaxis proceeding from the leaf 0. b JA and JA-Ile JA levels in treated local leaves 0. c JA and JA-Ile accumulation in local leaves 0 and in younger systemic leaves at different times after W + OS treatment. d JA and JA-Ile levels in local and systemic leaves 90 min after W + OS treatment. Values are mean ± SE; N = 5; n.d. = not detectable.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4263023&req=5

Fig1: W + OS-induced JA accumulation in local and systemic leaves. The leaves undergoing source-sink transition, designated as the leaves 0, were wounded with a pattern wheel and 20 μl of 1/5 diluted M. sexta OS were immediately applied to wounds (W + OS). Samples were harvested at indicated times, and their JA and JA-Ile contents were analyzed. a Numbering of the leaf positions in a bolting N. attenuata plant and the additive angular distances assuming 3/8 phyllotaxis proceeding from the leaf 0. b JA and JA-Ile JA levels in treated local leaves 0. c JA and JA-Ile accumulation in local leaves 0 and in younger systemic leaves at different times after W + OS treatment. d JA and JA-Ile levels in local and systemic leaves 90 min after W + OS treatment. Values are mean ± SE; N = 5; n.d. = not detectable.

Mentions: Given the central role of JA in regulating plant resistance to herbivores, we first examined whether simulated herbivore feeding induces systemic JA production. Because JA-Ile, the conjugate of JA and isoleucine, but not JA itself, functions as the active jasmonate hormone [27], the concentrations of JA-Ile were also determined. Slightly elongated plants (about 10 cm in height, Figure 1a) were wounded at node 0 [local leaf; hereafter leaf 0, and leaves X were used for naming the leaves at node X (X represents the node number)], which was the second fully expanded leaf, and 20 μl of 1/5-diluted M. sexta OS were applied to the wounds (W + OS) to simulate M. sexta herbivory. JA and JA-Ile levels in local and systemic leaves were determined using a HPLC-MS/MS method. In the treated leaves, JA and JA-Ile levels increased after 10 min, the levels were highest 1 h after the treatments, and decreased to almost the basal levels 2.5 h after induction (Figure 1b). In contrast, JA and JA-Ile levels in systemic leaves showed a very distinct pattern. JA accumulated almost exclusively in leaves +3, with the highest levels 90 min after elicitation, whereas the other systemic leaves contained only minor amounts (Figure 1c). Importantly, the JA levels in leaves +3 were remarkable high: at 90 min after W + OS treatment, JA contents reached up to 6 μg g−1 fresh mass (FM) JA, which were more than twice as much as the highest JA levels detected in the local leaves. The systemic distribution of JA-Ile was similar to that of JA but the highest levels in leaves +3 did not exceed those detected in local leaves, although 90 min after W + OS treatment JA-Ile contents in leaves +3 were also 2-fold greater than those in local leaves (Figure 1c). To determine whether systemic JA accumulations were limited to younger leaves, we elicited leaves 0 with W + OS and quantified JA and JA-Ile levels in leaves −4 (4 positions older than the elicited leaf) to leaves +4 (the youngest leaf) 90 min after W + OS elicitation (Figure 1d). Again, leaves +3 accumulated high JA levels (about 6.5 μg g−1 FM), but increased contents of JA could also be detected in leaves −3 -2, and +2, with 1, 0.45, and 0.4 μg g−1 FM, respectively (Figure 1d). Remarkably, these leaves accumulated relative high amounts of JA-Ile: leaves −3 contained 225 ng g−1 FM, as did leaves +3 (Figure 1d).Figure 1


Fatty acid-amino acid conjugates are essential for systemic activation of salicylic acid-induced protein kinase and accumulation of jasmonic acid in Nicotiana attenuata.

Hettenhausen C, Heinrich M, Baldwin IT, Wu J - BMC Plant Biol. (2014)

W + OS-induced JA accumulation in local and systemic leaves. The leaves undergoing source-sink transition, designated as the leaves 0, were wounded with a pattern wheel and 20 μl of 1/5 diluted M. sexta OS were immediately applied to wounds (W + OS). Samples were harvested at indicated times, and their JA and JA-Ile contents were analyzed. a Numbering of the leaf positions in a bolting N. attenuata plant and the additive angular distances assuming 3/8 phyllotaxis proceeding from the leaf 0. b JA and JA-Ile JA levels in treated local leaves 0. c JA and JA-Ile accumulation in local leaves 0 and in younger systemic leaves at different times after W + OS treatment. d JA and JA-Ile levels in local and systemic leaves 90 min after W + OS treatment. Values are mean ± SE; N = 5; n.d. = not detectable.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4263023&req=5

Fig1: W + OS-induced JA accumulation in local and systemic leaves. The leaves undergoing source-sink transition, designated as the leaves 0, were wounded with a pattern wheel and 20 μl of 1/5 diluted M. sexta OS were immediately applied to wounds (W + OS). Samples were harvested at indicated times, and their JA and JA-Ile contents were analyzed. a Numbering of the leaf positions in a bolting N. attenuata plant and the additive angular distances assuming 3/8 phyllotaxis proceeding from the leaf 0. b JA and JA-Ile JA levels in treated local leaves 0. c JA and JA-Ile accumulation in local leaves 0 and in younger systemic leaves at different times after W + OS treatment. d JA and JA-Ile levels in local and systemic leaves 90 min after W + OS treatment. Values are mean ± SE; N = 5; n.d. = not detectable.
Mentions: Given the central role of JA in regulating plant resistance to herbivores, we first examined whether simulated herbivore feeding induces systemic JA production. Because JA-Ile, the conjugate of JA and isoleucine, but not JA itself, functions as the active jasmonate hormone [27], the concentrations of JA-Ile were also determined. Slightly elongated plants (about 10 cm in height, Figure 1a) were wounded at node 0 [local leaf; hereafter leaf 0, and leaves X were used for naming the leaves at node X (X represents the node number)], which was the second fully expanded leaf, and 20 μl of 1/5-diluted M. sexta OS were applied to the wounds (W + OS) to simulate M. sexta herbivory. JA and JA-Ile levels in local and systemic leaves were determined using a HPLC-MS/MS method. In the treated leaves, JA and JA-Ile levels increased after 10 min, the levels were highest 1 h after the treatments, and decreased to almost the basal levels 2.5 h after induction (Figure 1b). In contrast, JA and JA-Ile levels in systemic leaves showed a very distinct pattern. JA accumulated almost exclusively in leaves +3, with the highest levels 90 min after elicitation, whereas the other systemic leaves contained only minor amounts (Figure 1c). Importantly, the JA levels in leaves +3 were remarkable high: at 90 min after W + OS treatment, JA contents reached up to 6 μg g−1 fresh mass (FM) JA, which were more than twice as much as the highest JA levels detected in the local leaves. The systemic distribution of JA-Ile was similar to that of JA but the highest levels in leaves +3 did not exceed those detected in local leaves, although 90 min after W + OS treatment JA-Ile contents in leaves +3 were also 2-fold greater than those in local leaves (Figure 1c). To determine whether systemic JA accumulations were limited to younger leaves, we elicited leaves 0 with W + OS and quantified JA and JA-Ile levels in leaves −4 (4 positions older than the elicited leaf) to leaves +4 (the youngest leaf) 90 min after W + OS elicitation (Figure 1d). Again, leaves +3 accumulated high JA levels (about 6.5 μg g−1 FM), but increased contents of JA could also be detected in leaves −3 -2, and +2, with 1, 0.45, and 0.4 μg g−1 FM, respectively (Figure 1d). Remarkably, these leaves accumulated relative high amounts of JA-Ile: leaves −3 contained 225 ng g−1 FM, as did leaves +3 (Figure 1d).Figure 1

Bottom Line: Previous studies mainly focused on individual responses and a limited number of systemic leaves, and more research is needed for a better understanding of how different plant parts respond to herbivory.In contrast to the activation of SIPK and elevation of JA in specific systemic leaves, increases in the activity of an important anti-herbivore defense, trypsin proteinase inhibitor (TPI), were observed in all systemic leaves after simulated herbivory, suggesting that systemic TPI induction does not require SIPK activation and JA increases.Leaf ablation experiments demonstrated that within 10 minutes after simulated herbivory, a signal (or signals) was produced and transported out of the treated leaves, and subsequently activated systemic responses.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Herbivory induces the activation of mitogen-activated protein kinases (MAPKs), the accumulation of jasmonates and defensive metabolites in damaged leaves and in distal undamaged leaves. Previous studies mainly focused on individual responses and a limited number of systemic leaves, and more research is needed for a better understanding of how different plant parts respond to herbivory. In the wild tobacco Nicotiana attenuata, FACs (fatty acid-amino acid conjugates) in Manduca sexta oral secretions (OS) are the major elicitors that induce herbivory-specific signaling but their role in systemic signaling is largely unknown.

Results: Here, we show that simulated herbivory (adding M. sexta OS to fresh wounds) dramatically increased SIPK (salicylic acid-induced protein kinase) activity and jasmonic acid (JA) levels in damaged leaves and in certain (but not all) undamaged systemic leaves, whereas wounding alone had no detectable systemic effects; importantly, FACs and wounding are both required for activating these systemic responses. In contrast to the activation of SIPK and elevation of JA in specific systemic leaves, increases in the activity of an important anti-herbivore defense, trypsin proteinase inhibitor (TPI), were observed in all systemic leaves after simulated herbivory, suggesting that systemic TPI induction does not require SIPK activation and JA increases. Leaf ablation experiments demonstrated that within 10 minutes after simulated herbivory, a signal (or signals) was produced and transported out of the treated leaves, and subsequently activated systemic responses.

Conclusions: Our results reveal that N. attenuata specifically recognizes herbivore-derived FACs in damaged leaves and rapidly send out a long-distance signal to phylotactically connected leaves to activate MAPK and JA signaling, and we propose that FACs that penetrated into wounds rapidly induce the production of another long-distance signal(s) which travels to all systemic leaves and activates TPI defense.

Show MeSH