C4 Photosynthetic Gene Expression in Light- and Dark-Grown Amaranth Cotyledons

Abstract

l h e patterns of expression for genes encoding several C, photosynthetic enzymes were examined in light-grown and dark-grown (etiolated) cotyledons of amaranth (Amaranfhus hypochondriacus), a dicotyledonous C4 plant. l h e large subunit and small subunit of ribulose-1,s-bisphosphate carboxylase (RuBPCase), phosphoenolpyruvate carboxylase (PEPCase), and pyruvate orthophosphate dikinase (PPdK) were all present in the cotyledons by d 2 after planting when the seedlings first emerged from the seed coat. Kranz anatomy was apparent in light-grown cotyledons throughout development, and the overall patterns of C, gene expression were similar to those recently described for developing amaranth leaves RuBPCase mRNA and proteins were present in both bundle sheath and mesophyll cells in a CJike pattern during early development and became progressively more localized to bundle sheath cells in the C4-type pattern as the cotyledons expanded over 2 to 7 d.PEPCase and PPdK polypeptides were localized to mesophyll cells throughout development, even though PEPCase transcripts were detected in both bundle sheath and mesophyll cells. Kranz anatomy also developed in cotyledons grown in complete darkness. In 7-dold dark-grown cotyledons, RuBPCase, PPdK, and PEPCase were all localized to the appropriate cell types, although at somewhat lower levels than in light-grown cotyledons. These findings demonstrate that the leaves and postembryonic cotyledons of amaranth undergo common developmental programs of C, gene expression during maturation. Furthermore, light is not required for the celltype-specific expression of genes encoding RuBPCase and other photosynthetic enzymes in this dicotyledonous C, plant.

The biology of Canadian weeds. 130. Amaranthus retroflexus L., A. powellii S. Watson and A. hybridus L.

“…The first true leaf becomes visible at 7 d, and it starts to function as a photosynthetic source after another two or 3 d, when they are 12-13 mm long (Wang et al 1993). During this period, the cotyledons are the only photosynthetic source for the young seedlings.…”

“…have the C 4 pathway of photosynthesis (see Weaver and McWilliams 1980;Kigel 1994) and exhibit the characteristic Kranz anatomy in leaves, cotyledons (Wang et al 1993) and bracts (Costea and Tardif 2003c). Their photosynthetic pathway is characterized by the use of the mitochondrial NAD-ME to decarboxylate malate in the Kranz bundle-sheaths (Long et al 1994;Long and Berry 1996).…”

“…cell elongation (Wang et al 1993). The first true leaf becomes visible at 7 d, and it starts to function as a photosynthetic source after another two or 3 d, when they are 12-13 mm long (Wang et al 1993).…”

Leaf Development in the Single-Cell C4 System in Bienertia sinuspersici: Expression of Genes and Peptide Levels for C4 Metabolism in Relation to Chlorenchyma Structure under Different Light Conditions

“…The expression of NAD-ME requires illumination, while PPDK and PEPC expression in mesophyll cells is independent of light. In leaves and cotyledons of this species, the early developmental process can influence the establishment of cell type-specific expression (Wang et al, 1992(Wang et al, , 1993Long and Berry, 1996). In both maize and amaranth, the establishment of mesophyll and bundle sheath cell-specific gene expression are separate events that occur during different stages of leaf development.…”

Expression Profiles of <i>psbA, ALS, EPSPS</i>, and Other Chloroplastic Genes in Response to PSII-, ALS-, and EPSPS-Inhibitor Treatments in <i>Kochia scoparia</i>

“…The expression of Rubisco is dependent on various factors such as light [47] [48], cell and tissue type [49] [50], efficiency of photosynthetic machinery [51], phytohormone and nutrient levels [52] [53], and plant developmental stage [54]. Rubisco consists of two subunits (large and small), encoded by two separate genes (chloroplastic large subunit, LSU and nuclear small subunit, SSU) [55].…”