Glutamine synthetase polypeptides in the roots of 55 legume species in relation to their climatic origin and the partitioning of nitrate assimilation

A - Papers appearing in refereed journals

Woodall, J. and Forde, B. G. 1996. Glutamine synthetase polypeptides in the roots of 55 legume species in relation to their climatic origin and the partitioning of nitrate assimilation. Plant, Cell and Environment. 19 (7), pp. 848-858.

AuthorsWoodall, J. and Forde, B. G.
Abstract

Glutamine synthetase (GS) exists as two main isoforms in plants, a cytosolic form (GS1) and a chloroplast or plastidic form (GS2). Fifty-five species of legume, representing a phylogenetically diverse group of tropical and temperate species, were screened by western blotting for the presence of GS2 in their roots. A remarkably strong correlation was found between the climatic origin of the species and the presence or absence of a GS2-like polypeptide in the root. Root GS2 was found in all 31 temperate species examined (30 papilionoids, one caesalpinoid), but was not detected in any of the 17 tropical papilionoid species. It was also absent in the roots of four out of seven tropical non-papilionoid species. The 'in vivo' NR activities of roots, stems and leaves of 46 of the legume species were analysed to establish their major site of nitrate reduction, and the ratio of nitrate:reduced N in the xylem sap was determined for some species, but no clear correlation between possession of a root GS2 and a preference for root nitrate assimilation was found. We discuss the possibility that expression of GS2 in the root was part of a more extensive physiological adaptation to root nitrate assimilation that evolved in temperate species to suit the alkaline, nitrate-rich soils found in the centres of origin in temperate latitudes.

KeywordsPlant Sciences
Year of Publication1996
JournalPlant, Cell and Environment
Journal citation19 (7), pp. 848-858
Digital Object Identifier (DOI)doi:10.1111/j.1365-3040.1996.tb00421.x
Open accessPublished as non-open access
Funder project or code114
212
442
ISSN01407791
PublisherWiley

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