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Query: EC:1.7.1.2 (
nitrate reductase
)
3,861
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
We investigated the effects of salt-sensitive signaling molecules on ionic fluxes and gene expression related to K
+
/Na
+
homeostasis in a perennial herb,
Glycyrrhiza uralensis
, during short-term NaCl stress (100 mM, 24 h). Salt treatment caused more pronounced Na
+
accumulation in root cells than in leaf cells. Na
+
ions were mostly compartmentalized in vacuoles. Roots exposed to NaCl showed increased levels of extracellular ATP (eATP), cytosolic Ca
2+
, H
2
O
2
, and NO. Steady-state flux recordings revealed that these salt-sensitive signaling molecules enhanced NaCl-responsive Na
+
efflux, due to the activated Na
+
/H
+
antiport system in the plasma membrane (PM). Moreover, salt-elicited K
+
efflux, which was mediated by depolarization-activated cation channels, was reduced with the addition of Ca
2+
, H
2
O
2
, NO, and eATP. The salt-adaptive effects of these molecules (Na
+
extrusion and K
+
maintenance) were reduced by pharmacological agents, including LaCl
3
(a PM Ca
2+
channel inhibitor), DMTU (a reactive oxygen species scavenger), cPTIO (an NO scavenger), or PPADS (an antagonist of animal PM purine P2 receptors). RT-qPCR data showed that the activation of the PM Na
+
/H
+
antiport system in salinized roots most likely resulted from the upregulation of two genes,
GuSOS1
and
GuAHA
, which encoded the PM Na
+
/H
+
antiporter, salt overly sensitive 1 (SOS1), and H
+
-ATPase, respectively. Clear interactions occurred between these salt-sensitive agonists to accelerate transcription of salt-responsive signaling pathway genes in
G. uralensis
roots. For example, Ca
2+
, H
2
O
2
, NO, and eATP promoted transcription of
GuSOS3
(salt overly sensitive 3) and/or
GuCIPK
(CBL-interacting protein kinase) to activate the predominant Ca
2+
-SOS signaling pathway in salinized liquorice roots. eATP, a novel player in the salt response of
G. uralensis
, increased the transcription of
GuSOS3, GuCIPK
,
GuRbohD
(respiratory burst oxidase homolog protein D),
GuNIR
(
nitrate reductase
),
GuMAPK3
, and
GuMAPK6
(the
mitogen-activated protein
kinases 3 and 6). Moreover,
GuMAPK3
and
GuMAPK6
expression levels were enhanced by H
2
O
2
in NaCl-stressed
G. uralensis
roots. Our results indicated that eATP triggered downstream components and interacted with Ca
2+
, H
2
O
2
, and NO signaling to maintain K
+
/Na
+
homeostasis. We propose that a multiple signaling network regulated K
+
/Na
+
homeostasis in NaCl-stressed
G. uralensis
roots.
...
PMID:Salt-Sensitive Signaling Networks in the Mediation of K
+
/Na
+
Homeostasis Gene Expression in
Glycyrrhiza uralensis
Roots. 2885 12
The participation of nitric oxide (NO) in the responses of plants towards biotic and abiotic stresses is well established. However, the mechanism involved particularly in cold acclimation-induced chilling tolerance remains elusive. Here we show the cold acclimation induced-chilling tolerance was associated with inductions of
nitrate reductase
(NR)-dependent NO production, S-nitrosylated glutathione reductase (GSNOR) activity and
mitogen-activated protein
kinases MPK1/2 activation in tomato plants. Silencing of NR resulted in decreased GSNOR activity and MPK1/2 activation, which subsequently compromised cold acclimation-induced chilling tolerance. By contrast, silencing of GSNOR caused decreased NR activity, increased NO accumulation and MPK1/2 activation, and enhanced cold acclimation-induced chilling tolerance. Furthermore, co-silencing of MPK1 and MPK2 attenuated the NR-dependent NO production and cold acclimation-induced tolerance to chilling. Results from present study suggest the importance of MPK1/2 for the induction of NR-dependent NO generation, while the accumulation of nitrosylated glutathione from NO-derived reactive nitrogen species could potentially S-nitrosylate NR. These findings provide new insight into the crosstalk of NO and MPK1/2 in cold acclimation-induced chilling tolerance in tomato plants.
...
PMID:Crosstalk between Nitric Oxide and MPK1/2 Mediates Cold Acclimation-induced Chilling Tolerance in Tomato. 2903 50
