Cellular expression of C3 and C4 photosynthetic enzymes in the amphibious sedge Eleocharis retroflexa ssp. chaetaria.
The amphibious leafless sedge Eleocharis retroflexa ssp. chaetaria expresses C(4)-like biochemical characteristics in both the terrestrial and submerged forms. Culms of the terrestrial form have Kranz anatomy, whereas those of the submerged form have Kranz-like anatomy combined with anatomical features of aquatic plant leaves. We examined the immunolocalization of C(3) and C(4) enzymes in culms of the two forms. In both forms, phosphoenolpyruvate carboxylase; pyruvate, Pi dikinase; and NAD-malic enzyme were compartmentalized between the mesophyll (M) and Kranz cells, but their levels were somewhat reduced in the submerged form. In the terrestrial form, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) occurred mainly in the Kranz cells, and weakly in the M chloroplasts. In the submerged form, the rubisco occurred at higher levels in the M cells than in the terrestrial form. In both forms, the C(4) pattern of enzyme expression was clearer in the M cells adjacent to Kranz cells than in distant M cells. During the transition from terrestrial to submerged conditions, the enzyme expression pattern changed in submerged mature culms that had been formed in air before submergence, and matched that in culms newly developed underwater. It seems that effects of both environmental and developmental factors overlap in the C(4) pattern expression in this plant.
Plant Physiology Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan. uenoos@nias.affrc.go.jp
Osamu
O
Ueno
Masataka
M
Wakayama
D031256:Eleocharis / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development; D004777:Environment; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D007101:Immersion; D007150:Immunohistochemistry; D008291:Malate Dehydrogenase / Q000096:biosynthesis; D010730:Phosphoenolpyruvate Carboxylase / Q000096:biosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000096:biosynthesis*; D035261:Plant Components, Aerial / Q000201:enzymology; D011772:Pyruvate, Orthophosphate Dikinase / Q000096:biosynthesis; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis
D045322:Photosynthetic Reaction Center Complex Proteins; D008291:Malate Dehydrogenase; C046446:malate dehydrogenase-(oxaloacetate-decarboxylating) (NAD+); D011772:Pyruvate, Orthophosphate Dikinase; D010730:Phosphoenolpyruvate Carboxylase; D012273:Ribulose-Bisphosphate Carboxylase