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Target Concepts:
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Query: EC:4.1.1.32 (
phosphoenolpyruvate carboxykinase
)
4,204
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Sodic-alkalinity is a more seriously limiting factor in agricultural productivity than salinity. Oat (
Avena nuda
) is a salt-tolerant crop species and is therefore useful in studying the physiological responses of cereals to alkalinity. We evaluated the differential effects of sodic-alkalinity on two naked oat lines, Caoyou1 and Yanke1. Seedlings of the two lines were exposed to 50 mM alkaline salt mixture of NaHCO
3
and Na
2
CO
3
(18:1 molar ratio; pH 8.5) for 2 weeks in a soil environment. Sodic-alkalinity exposure led the assimilation of abundant Na
+
at similar concentrations in the organs of both lines. However, Caoyou1 showed much stronger growth than Yanke1, exhibiting a higher dry weight, total leaf area, and shoot height under sodic-alkalinity. Further analysis showed that Caoyou1 was more sodic-alkalinity tolerance than Yanke1. This was firstly because of differences in the oxidative stress defense mechanisms in leaves of the two lines. Antioxidant enzyme activities were either slightly elevated (catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GP), glutathione reductase (GR)) or unaltered (superoxide dismutase (SOD)) in Caoyou1 leaves, but some enzyme (SOD, GPOX, GR) activities were significantly reduced in Yanke1.
An
APX1 transcript levels significantly increased in Caoyou1 under sodic-alkalinity conditions compared with Yanke1, indicating its better antioxidant capacity. Secondly, the related parameters of Mg
2+
concentration,
phosphoenolpyruvate carboxylase
(
PEPC
) activity, and
An
PEPC
transcript levels in the leaves showed significantly higher values in Caoyou1 compared with Yanke1. This demonstrated the effective utilization by Caoyou1 of accumulated HCO
3
-
in the irreversible reaction from phosphoenolpyruvate to oxaloacetate to produce inorganic
phosphorus
, which was elevated in Caoyou1 leaves under alkalinity stress. Overall, the results demonstrated that the greater sodic-alkalinity tolerance of Caoyou1 is the result of: (1) maintained antioxidant enzyme activities; and (2) a higher capacity for the phosphoenolpyruvate to oxaloacetate reactions, as shown by the higher
PEPC
activity, Mg
2+
concentration, and total
phosphorus
concentration in its leaves, despite the lower soil pH.
...
PMID:Differences in Physiological Responses of Two Oat (
Avena nuda
L.) Lines to Sodic-Alkalinity in the Vegetative Stage. 3293 50
Nutrient imbalances cause the deterioration of tree health in European forests, but the underlying physiological mechanisms are unknown. Here, we investigated the consequences of decreasing root carbohydrate reserves for
phosphorus
(P) mobilization and uptake by forest trees. In P-rich and P-poor beech (Fagus sylvatica) forests, naturally grown, young trees were girdled and used to determine root, ectomycorrhizal and microbial activities related to P mobilization in the organic layer and mineral topsoil in comparison with those in non-girdled trees. After girdling, root carbohydrate reserves decreased. Root
phosphoenolpyruvate carboxylase
activities linking carbon and P metabolism increased. Root and ectomycorrhizal phosphatase activities and the abundances of bacterial genes catalysing major steps in P turnover increased, but soil enzymes involved in P mobilization were unaffected. The physiological responses to girdling were stronger in P-poor than in P-rich forests. P uptake was decreased after girdling. The soluble and total P concentrations in roots were stable, but fine root biomass declined after girdling. Our results support that carbohydrate depletion results in reduced P uptake, enhanced internal P remobilization and root biomass trade-off to compensate for the P shortage. Since reductions in root biomass render trees more susceptible to drought, our results link tree deterioration with disturbances in the P supply as a consequence of decreased belowground carbohydrate allocation.
...
PMID:Carbohydrate depletion in roots impedes phosphorus nutrition in young forest trees. 3312 21
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