Reference "Low-oxygen stress and water deficit induce cytosolic pyruvate orthophosphate dikinase (PPDK) expression in roots of rice, a C3 plant"

Reference ID

2909

Title

Low-oxygen stress and water deficit induce cytosolic pyruvate orthophosphate dikinase (PPDK) expression in roots of rice, a C3 plant

Source

The Plant journal : for cell and molecular biology, 1998, vol. 15, pp. 89-98

Authors (3)

Moons-A	Valcke-R
Van_Montagu-M

Abstract

Pyruvate orthophosphate dikinase (PPDK) is known for its role in C4
photosynthesis but has no established function in C3 plants. Abscisic acid, PEG
and submergence were found to markedly induce a protein of about 97 kDa,
identified by microsequencing as PPDK, in rice roots (C3). The rice genome was
found to contain two ppdk loci, osppdka and osppdkb. We isolated osppdka cDNA,
which encodes a cytosolic rice PPDK isoform of 96.6 kDa, that corresponded to
the ABA-induced protein from roots. Western blot analysis showed a PPDK
induction in roots of rice seedlings during gradual drying, cold, high salt and
mannitol treatment, indicating a water deficit response. PPDK was also induced
in the roots and sheath of submerged rice seedlings, and in etiolated rice
seedlings exposed to an oxygen-free N2 atmosphere, which indicated a low-oxygen
stress response. None of the stress treatments induced PPDK protein accumulation
in the lamina of green rice seedlings. Ppdk transcripts were found to accumulate
in roots of submerged seedlings, concomitant with the induction of alcohol
dehydrogenase 1. Low-oxygen stress triggered an increase in PPDK activity in
roots and etiolated rice seedlings, accompanied by increases in
phosphoenolpyruvate carboxylase and malate dehydrogenase activities. The results
indicate that cytosolic PPDK is involved in a metabolic response to water
deficit and low-oxygen stress in rice, an anoxia-tolerant species.