Antisense reduction of serine hydroxymethyltransferase results in diurnal displacement of NH+4 assimilation in leaves of Solanum tuberosum

A - Papers appearing in refereed journals

Schoerring, J. K., Mack, G., Nielsen, K. H., Husted, S., Suzuki, A., Driscoll, S. P., Boldt, R. and Bauwe, H. 2006. Antisense reduction of serine hydroxymethyltransferase results in diurnal displacement of NH+4 assimilation in leaves of Solanum tuberosum. The Plant Journal. 45 (1), pp. 71-82.

AuthorsSchoerring, J. K., Mack, G., Nielsen, K. H., Husted, S., Suzuki, A., Driscoll, S. P., Boldt, R. and Bauwe, H.
Abstract

Serine hydroxymethyltransferase (SHMT) is part of the mitochondrial enzyme complex catalysing the photorespiratory production of serine, ammonium and CO2 from glycine. Potato plants (Solanum tuberosum cv. Solara) with antisensed SHMT were generated to investigate whether photorespiratory intermediates accumulated during light lead to nocturnal activation of the nitrogen-assimilating enzymes glutamine synthetase (GS) and glutamate synthase (GOGAT). The transformant lines contained 70-90% less SHMT protein, and exhibited a corresponding decrease in mitochondrial SHMT activity. SHMT antisense plants displayed lower photosynthetic capacity and accumulated glycine in light. Glycine was converted to serine in the second half of the light period, while serine, ammonium and glutamine showed an inverse diurnal rhythm and reached highest values in darkness. GS/GOGAT protein levels and activities in the transgenics also reached maximum levels in darkness. The diurnal displacement of NH4+ assimilation was accompanied by a change in the subunit composition of GS(2), but not GS(1). It is concluded that internal accumulation of post-photorespiratory ammonium is leading to nocturnal activation of GS/GOGAT, and that the time shift in ammonia assimilation can constitute part of a strategy to survive photorespiratory impairment.

KeywordsPlant Sciences
Year of Publication2006
JournalThe Plant Journal
Journal citation45 (1), pp. 71-82
Digital Object Identifier (DOI)doi:10.1111/j.1365-313X.2005.02598.x
PubMed ID16367955
Open accessPublished as non-open access
Funder project or code502
Redox signalling and oxidative-stress-mediated control of plant growth and development
ISSN09607412
0960-7412
PublisherWiley

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