TY - JOUR

T1 - Activity of biochemical pH-stat enzymes in cereal root tips under oxygen deficiency

AU - Kulichikhin, K. Yu

AU - Chirkova, T. V.

AU - Fagerstedt, K. V.

N1 - Funding Information: ACKNOWLEDGMENTS This work was supported by the Academy of Finland (Suomen Akatemia), project nos. 171987, 178918, and 1207898.

PY - 2009/5

Y1 - 2009/5

N2 - The activity of the enzymes of alcoholic and lactic-acid fermentation: pyruvate decarboxylase (PDC, EC 4.1.1.1), alcohol dehydrogenase (ADH, EC 1.1.1.1), lactate dehydrogenase (LDH, EC 1.1.1.27) and the enzymes of malic acid metabolism: phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.23), NAD-dependent malate dehydrogenase (NAD-MDH, EC 1.1.1.37), and NADP-dependent malic enzyme (NADP-ME, EC 1.1.1.40) involved in the operation of biochemical pH-stat was investigated in the root tips of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) under hypoxia and anoxia. Exposures lasted for 6, 12, and 18 h. The most pronounced response was detected for the enzymes of alcoholic fermentation. The activation of ADH and PDC in wheat occurred only under hypoxia, whereas in rice it was detected both under hypoxia and anoxia. The activation of LDH in wheat occurred under hypoxia, and in rice, the activity of this enzyme was slightly enhanced. The activity of the enzymes of malic acid metabolism did not change except in wheat root tips under hypoxia when PEPC activity decreased and NADP-ME activity simultaneously rose. The role of biochemical pH-stat in the regulation of cytoplasmic pH in plant cells under oxygen deficit and the mechanisms for regulating the activities of enzymes involved in biochemical pH-stat are discussed as well as the interaction between biochemical pH-stat and other mechanisms maintaining pH of plant cells. The results are analyzed within a context of intracellular pH regulation.

AB - The activity of the enzymes of alcoholic and lactic-acid fermentation: pyruvate decarboxylase (PDC, EC 4.1.1.1), alcohol dehydrogenase (ADH, EC 1.1.1.1), lactate dehydrogenase (LDH, EC 1.1.1.27) and the enzymes of malic acid metabolism: phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.23), NAD-dependent malate dehydrogenase (NAD-MDH, EC 1.1.1.37), and NADP-dependent malic enzyme (NADP-ME, EC 1.1.1.40) involved in the operation of biochemical pH-stat was investigated in the root tips of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) under hypoxia and anoxia. Exposures lasted for 6, 12, and 18 h. The most pronounced response was detected for the enzymes of alcoholic fermentation. The activation of ADH and PDC in wheat occurred only under hypoxia, whereas in rice it was detected both under hypoxia and anoxia. The activation of LDH in wheat occurred under hypoxia, and in rice, the activity of this enzyme was slightly enhanced. The activity of the enzymes of malic acid metabolism did not change except in wheat root tips under hypoxia when PEPC activity decreased and NADP-ME activity simultaneously rose. The role of biochemical pH-stat in the regulation of cytoplasmic pH in plant cells under oxygen deficit and the mechanisms for regulating the activities of enzymes involved in biochemical pH-stat are discussed as well as the interaction between biochemical pH-stat and other mechanisms maintaining pH of plant cells. The results are analyzed within a context of intracellular pH regulation.

KW - Anoxia

KW - Biochemical pH-stat

KW - Hypoxia

KW - Oryza sativa

KW - Root tip

KW - Triticum aestivum

UR - http://www.scopus.com/inward/record.url?scp=65549110802&partnerID=8YFLogxK

U2 - 10.1134/S102144370903011X

DO - 10.1134/S102144370903011X

M3 - Article

AN - SCOPUS:65549110802

VL - 56

SP - 377

EP - 388

JO - Russian Journal of Plant Physiology

JF - Russian Journal of Plant Physiology

SN - 1021-4437

IS - 3

ER -