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Bienertia cycloptera Bunge ex Boiss., Chenopodiaceae, another C 4 Plant without Kranz Tissues 286
Author(s) -
Freitag H.,
Stichler W.
Publication year - 2002
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2002-20444
Subject(s) - biology , chloroplast , botany , chenopodiaceae , photosynthesis , starch , leaflet (botany) , vascular bundle , crassulacean acid metabolism , cytoplasm , biochemistry , gene
Following up an earlier study on Borszczowia aralocaspica, a second C 4 leaf type without Kranz tissues is described from Bienertia cycloptera Bunge ex Boiss. The species belongs also to tribe Suaedeae and grows in similar temporarily wet saline habitats in southwestern C Asia. Like Borszczowia, the species has the ability to perform C 4 photosynthesis in single chlorenchyma cells but the cytological compartmentation differs. Evidence is cited from anatomy (cytoplasmic compartmentation, starch formation), from carbon isotope composition and from indirect sources. It is documented by micrographs and δ 13 C values (mean ‐ 14.7 %). Variations of the δ 13 C values subsequently found in newly formed leaves of the same greenhouse plants (‐ 15.5 to ‐ 21.1 %) support the hypothesis that Bienertia is a facultative C 4 /C 3 species. The new described bienertioid leaf type differs from the leaves of C 3 species in Suaeda by strict separation of the mesophyll into a central aqueous tissue without chloroplasts and a peripheral 1 ‐ 3 layered chlorenchyma with elaborate cytoplasmic compartmentation. Each cell of the latter contains a peripheral cytoplasmic layer with scattered chloroplasts and a large globular cytoplasmic body located in the central vacuole which is densely packed with starch producing chloroplasts, and joined by the nucleus. Comparative studies on different leaves of the same individuals of ordinary C 4 species demonstrated a remarkable range of variation, from 1.0 % in Salsola tragus up to 2.5 % in Petrosimonia sibirica. This corresponds well with the variance in data from different individuals and populations. For explaining the larger interspecific variation from about 23 other species of Salsoloideae, the hypothesis is developed that in species or groups of taxa specific leakages of their C 4 systems do occur. By three characters unique in tribe Suaedeae and detected during the study, Bienertia is confirmed as well separated from Suaeda and as a monotypic genus.