KIM, INSUN. Biology Department, Keimyung University, Taegu 704-701, Korea. - Ultrastructure and immunolocalization of the C-4 photosynthetic enzyme in cotyledons and leaves of two Salsola species.
Some deviation in the type of photosynthesis and Kranz structure are
found in cotyledons and leaves of the same plant among the C-4
Salsola species. The current study attempted to reveal the
pattern of Kranz and cell-type-specific C-4 enzyme accumulation in
cotyledons and leaves of Salsola collina and S.
komarovii. Structural aspects of the bundle sheath and mesophyll
cell differentiation, as well as immunolocalization of the bundle
sheath cell-specific enzyme, RuBPCase, and the mesophyll cell-specific
enzyme, PEPCase, were used particularly in S. komarovii to
follow the development of the C-4 pattern. The study revealed the
Salsoloid Kranz type having either continuous or discontinuous
concentric chlorenchyma in all leaves and cotyledons. The Kranz
pattern and ultrastructure of the bundle sheath and mesophyll cell in
the cotyledons were almost identical to those of mature leaves in
S. komarovii, where cellular differentiation into the bundle
sheath cell and mesophyll cell occurred simultaneously with
development of the secondary plasmodesmata. Accumulation of RuBPCase
appeared early in the bundle sheath precursor cell stage. Strong
RuBPCase reaction was shown at the time of bundle sheath
tissue-delimitation and further on in developing stages. PEPCase was
restricted to the mesophyll cells and detected only in later stages at
low levels. The leaf/cotyledon structure in these species was
C4-S/C4-S, according to Pyankov et al. (2001), with a characteristic
bundle sheath- and mesophyll cell-specific C-4 enzyme accumulation
pattern.
Key words: C-4 photosynthesis, cotyledons, immunolocalization, Kranz pattern, leaves, Salsola species