A Remarkable New Leaf Type With Unusual Photosynthetic Tissue in a Central Asiatic Genus of Chenopodiaceae

Abstract

From the hygrohalophyte Borszczowia aralocaspica Bunge (Chenopodiaceae), a new leaf type with 1‐layered chlorenchyma is described as “borszczovoid” and compared with other leaf types in subfamily Salsoloideae. The chlorenchyma is suspected to represent a unique C4 type. Evidence is cited from anatomical studies and documented by micrographs and Carbon isotope determinations (ä13C values). The 1‐layered photosynthetic tissue combines all essential anatomical characters of a 2‐layered chlorenchyma of regular C4 plants and is in intimate contact with concentrically arranged peripheral bundles. The ä13C values are − 13.03 ‰ from young stems and − 13.78 ‰ from leaves. The results are discussed in the anatomical, physiological and taxonomic framework. In addition, from distantly‐related Suaeda species of section Conosperma the conospermoid leaf type is re‐described. It is characterized by typical palisade and Kranz layers and differs from the C4 suaedoid type by an external water‐storaging hypodermis and an arrangement of Kranz cells reminiscent of the atriplicoid type from subfamily Chenopodioideae. From eight other species of Chenopodiaceae ä13C values are given for the first time.

What Does It Take to Be C4? Lessons from the Evolution of C4 Photosynthesis

“…Doubling of atmospheric CO 2 concentration, confidently expected to occur in the second one-half of the 21st century, may itself mitigate the Rubisco penalty in many C 3 plants in many habitats (except perhaps where accompanied by higher temperatures and drought), with little impact on assimilation or growth of C 4 plants (7). This global experiment will certainly test our assumptions as to what it means to be C 4 , and what value C 4 Oryza then? Quo vadis, C 4 ?…”

Pollen morphological studies in subfamily Suaedoideae (Chenopodiaceae)

“…The subfamily is characterised by fleshy leaves, the presence of bracteoles, membranaceous in Suaeda or usually herbaceous in Bienertia, and seeds with a usually crustaceous testa. Suaedoideae is a very interesting group, and unique among terrestrial plants in having a large diversity of photosynthetic types; notably in three species belonging to Suaeda and Bienertia, which undergo C 4 photosynthesis but do not have 'Kranz anatomy' (Haberlandt, 1914): both species of Bienertia (B. cycloptera and B. sinuspersici) and one species of Suaeda: S. aralocaspica (see Table I; and Freitag & Stichler, 2000Akhani et al, 2003Akhani et al, , 2005Edwards et al, 2004;Kapralov et al, 2006). The members of Suaedoideae are important characteristic components of arid and semi-arid inland saline communities and salt marsh habitats, with the exception of some species of Suaeda section Brezia which also occur in salt marshes of mesic climates.…”

The Cytoskeleton Maintains Organelle Partitioning Required for Single-Cell C4 Photosynthesis in Chenopodiaceae Species

“…It has long been accepted that the cellular separation of biochemical functions in Kranz anatomy is required for the C 4 cycle to operate in terrestrial plants; recently, however, this paradigm has been broken with the discoveries of three species in the family Chenopodiaceae that are capable of performing the entire C 4 photosynthesis cycle in individual chlorenchyma cells of the leaf (Freitag and Stichler, 2000;Voznesenskaya et al, 2001Voznesenskaya et al, , 2002Freitag and Stichler, 2002;Edwards et al, 2004;Akhani et al, 2005) These discoveries have led to a reexamination of the requirements for C 4 photosynthesis and raise interesting questions about the evolution of the syndrome as well as the potential for engineering C 4 photosynthesis into C 3 crop plants without having to generate the dual cell system. In addition, they provide exquisite examples of the ability of plant cells to generate and maintain biochemically complex compartments based on both the partitioning of organelles and the differential regulation of gene expression in these organelles within the same cell.…”