This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Nakano, Y. Articles by Edwards, G. E. Search for Related Content PubMed PubMed Citation Articles by Nakano, Y. Articles by Edwards, G. E. Agricola Articles by Nakano, Y. Articles by Edwards, G. E.

Metabolism and Enzymology

Hill Reaction, Hydrogen Peroxide Scavenging, and Ascorbate Peroxidase Activity of Mesophyll and Bundle Sheath Chloroplasts of NADP-Malic Enzyme Type C₄ Species ¹

Botany Department, Washington State University, Pullman, Washington 99164-4230

Intact mesophyll and bundle sheath chloroplasts wee isolated from the NADP-malic enzyme type C₄ plants maize, sorghum (monocots), and Flaveria trinervia (dicot) using enzymic digestion and mechanical isolation techniques. Bundle sheath chloroplasts of this C₄ subgroup tend to be agranal and were previously reported to be deficient in photosystem II activity. However, following injection of intact bundle sheath chloroplasts into hypotonic medium, thylakoids had high Hill reaction activity, similar to that of mesophyll chloroplasts with the Hill oxidants dichlorophenolindophenol, p-benzoquinone, and ferricyanide (approximately 200 to 300 micromoles O₂ evolved per mg chlorophyll per hour). In comparison to that of mesophyll chloroplasts, the Hill reaction activity of bundle sheath chloroplasts of maize and sorghum was labile and lost activity during assay. Bundle sheath chloroplasts of maize also exhibited some capacity for 3-phosphoglycerate dependent O₂ evolution (29 to 58 micromoles O₂ evolved per milligram chlorophyll per hour). Both the mesophyll and bundle sheath chloroplasts were equally effective in light dependent scavenging of hydrogen peroxide. The results suggest that both chloroplast types have noncyclic electron transport and the enzymology to reduce hydrogen peroxide to water. The activities of ascorbate peroxidase from these chloroplast types was consistent with their capacity to scavenge hydrogen peroxide.

¹ Supported by National Science Foundation grant DMB-8506197.

This article has been cited by other articles:

				B. S. Ripley, M. E. Gilbert, D. G. Ibrahim, and C. P. Osborne Drought constraints on C4 photosynthesis: stomatal and metabolic limitations in C3 and C4 subspecies of Alloteropsis semialata J. Exp. Bot., April 1, 2007; 58(6): 1351 - 1363. [Abstract] [Full Text] [PDF]