XVI International Botanical Congess
Rubisco activase is a chloroplast protein that regulates activation of rubisco, the enzyme that catalyzes photosynthetic uptake of carbon dioxide. Most species have two forms of rubisco activase, produced by alternative splicing of a common mRNA. These polypeptides differ in mass by approximately ten percent. The roles of the two forms are not known. Experiments with several species indicated that rubisco activase accumulation is altered by carbon dioxide concentration. The response to carbon dioxide varied between species, and within a species. The smaller form was more prevalent than the larger form in species examined. Growth of tomato at elevated carbon dioxide resulted in the smaller form increasing, relative to the larger form. Results of additional experiments on response of rubisco activase accumulation to temperature and light will be presented.