Comparison of spectrophotometric and radioisotopic methods for the assay of Rubisco in ozone-treated plants
Radioisotopic and spectrophotometric assays for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) initial and final activities and Rubisco content were compared in plants chronically exposed to ozone (O3) in a greenhouse and the field. In a greenhouse experiment, Glycine max was treated in exposure chambers with either charcoal-filtered air (CF air) or 100 nl O3 l-1 for 6 h daily during vegetative growth. Samples were collected after 7 days of exposure. In a field experiment, G. max was treated in open-top chambers with either CF air or nonfiltered air with O3 added at 1.5 times ambient O3 for 12 h daily. Average daily O3 concentrations were 21 and 92 nl l-1 in the CF and O3 treatments, respectively. Samples were collected during vegetative and reproductive growth. Both assays generally yielded comparable Rubisco initial and final activities for greenhouse-grown plants regardless of the O3 treatment. However for field-grown plants, Rubisco initial and final activities averaged 15 and 23% lower when assayed by the spectrophotometric rather than the radioisotopic method. For Rubisco content estimated by the spectrophotometric method, lower I2 values for the regression of Rubisco activity vs concentration of carboxyarabinitol-1,5-bisphosphate were observed in O3- than in CF-treated plants. Both assays yielded comparable Rubisco contents in the greenhouse and in the field although the variation was larger with the spectrophotometric method in field-grown plants. Growth conditions, field vs greenhouse, were more critical to the spectrophotometric assay performance than the O3 treatments for measurement of Rubisco activity and content.
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Related Subject Headings
- Plant Biology & Botany
- 3108 Plant biology
- 3008 Horticultural production
- 0706 Horticultural Production
- 0607 Plant Biology
- 0601 Biochemistry and Cell Biology
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Plant Biology & Botany
- 3108 Plant biology
- 3008 Horticultural production
- 0706 Horticultural Production
- 0607 Plant Biology
- 0601 Biochemistry and Cell Biology