Journal Article

Structural, biochemical, and physiological characterization of photosynthesis in two C<sub>4</sub> subspecies of <i>Tecticornia indica</i> and the C<sub>3</sub> species <i>Tecticornia pergranulata</i> (Chenopodiaceae)

Elena V. Voznesenskaya, Hossein Akhani, Nuria K. Koteyeva, Simon D. X. Chuong, Eric H. Roalson, Olavi Kiirats, Vincent R. Franceschi and Gerald E. Edwards

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 7, pages 1715-1734
Published in print May 2008 | ISSN: 0022-0957
Published online March 2008 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jxb/ern028
Structural, biochemical, and physiological characterization of photosynthesis in two C4 subspecies of Tecticornia indica and the C3 species Tecticornia pergranulata (Chenopodiaceae)

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Among dicotyledon families, Chenopodiaceae has the most C4 species and the greatest diversity in structural forms of C4. In subfamily Salicornioideae, C4 photosynthesis has, so far, only been found in the genus Halosarcia which is now included in the broadly circumscribed Tecticornia. Comparative anatomical, cytochemical, and physiological studies on these taxa, which have near-aphyllous photosynthetic shoots, show that T. pergranulata is C3, and that two subspecies of T. indica (bidens and indica) are C4 (Kranz-tecticornoid type). In T. pergranulata, the stems have two layers of chlorenchyma cells surrounding the centrally located water storage tissue. The two subspecies of T. indica have Kranz anatomy in reduced leaves and in the fleshy stem cortex. They are NAD-malic enzyme-type C4 species, with mesophyll chloroplasts having reduced grana, characteristic of this subtype. The Kranz-tecticornoid-type anatomy is unique among C4 types in the family in having groups of chlorenchymatous cells separated by a network of large colourless cells (which may provide mechanical support or optimize the distribution of radiation in the tissue), and in having peripheral vascular bundles with the phloem side facing the bundle sheath cells. Also, the bundle sheath cells have chloroplasts in a centrifugal position, which is atypical for C4 dicots. Fluorescence analyses in fresh sections indicate that all non-lignified cell walls have ferulic acid, a cell wall cross-linker. Structural–functional relationships of C4 photosynthesis in T. indica are discussed. Recent molecular studies show that the C4 taxa in Tecticornia form a monophyletic group, with incorporation of the Australian endemic genera of Salicornioideae, including Halosarcia, Pachycornia, Sclerostegia, and Tegicornia, into Tecticornia.

Keywords: C3 plants; C4 plants; Chenopodiaceae; chloroplast ultrastructure; Halosarcia; immunolocalization; NAD-ME type; photosynthetic enzymes; phylogeny; Tecticornia

Journal Article.  12656 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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