caa a22 4500 397521294 CHVBK 20180308164633.0 cr unu---uuuuu 161202e199509 xx s 000 0 eng 10.1093/jxb/46.special_issue.1293 doi (NATIONALLICENCE)oxford-10.1093/jxb/46.special_issue.1293 Rubisco: the consequences of altering its expression and activation in transgenic plants [Elektronische Daten] [T. John Andrews, Graham S. Hudson, Colleen J. Mate, Susanne von Caemmerer, John R. Evans, Yvonne B.C. Arvidsson] Transgenic tobacco (Nicotiana tabacum W38) hemizygous for a single antisense gene directed against Rubisco's small subunit had 35% of the Rubisco content of control leaves (15% when homozygous). CO2 assimilation (at 1000 μmol quanta m−2 s−1 and 350 μbar CO2) by the hemizygous leaves was reduced to 40% of that of the controls without material effect on stomatal conductance, chlorophyll content or other photosynthetic components. Leaf soluble protein was reduced commensurately with the reduction in Rubisco. CO2 assimilation rate in the hemizygous leaves remained limited by Rubisco activity at all, even very high, CO2 concentrations. This led to a simple, hyperbolic response of photosynthesis to intraplastid CO2 concentration from which the in vivo catalytic properties of Rubisco were inferred and compared with those of isolated Rubisco in vitro. Using a similar approach, the content of Rubisco activase was suppressed by incorporating a partial cDNA for activase into the tobacco genome in the antisense orientation with respect to a cauliflower mosaic virus 35S promoter. The progeny of a primary transformant with two anti-activase inserts had from < 1% to 20% of the activase content of control plants. Quite severe suppression of activase, to less than 5% of the amount present in control leaves, was required before effects on photosynthesis and growth became apparent, indicating that one activase tetramer must be able to service, continuously, as many as 200 Rubisco octamers. Plants with lower activase contents could not grow unless the atmosphere was enriched with CO2. Their Rubisco was less carbamylated and they had lower CO2 assimilation rates than the controls. The rate of release of 2′-carboxyarabinitol-1-phosphate from Rubisco after illumination of the antiactivase leaves was also impaired. Older anti-activase plants accumulated increasing amounts of Rubisco in their younger leaves, but were unable to carbamylate it. The photosynthetic rate per carbamylated Rubisco active site in the strongly suppressed anti-activase leaves was only approximately 25% of that seen in control leaves, suggesting that activase may not only promote carbamytation of uncarbamylated Rubisco sites, but also accelerate turnover at carbamylated sites. © 1995 Oxford University Press Photosynthetic Carbon Reduction nationallicence Rubisco nationallicence Rubisco activase nationallicence 2'- carboxy-arabinitol-1-phosphate nationallicence photosynthesis nationallicence regulation nationallicence Andrews T. John Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut Hudson Graham S. Co-operative Research Centre for Plant Sciences, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut Mate Colleen J. Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut von Caemmerer Susanne Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut Evans John R. Environmental Biology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut Arvidsson Yvonne B.C. Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut Journal of Experimental Botany Oxford University Press 46/special_issue(1995-09), 1293-1300 0022-0957 46:special_issue<1293 1995 46 exbotj https://doi.org/10.1093/jxb/46.special_issue.1293 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jxb/46.special_issue.1293 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Andrews T. John Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut NATIONALLICENCE 700 1- Hudson Graham S. Co-operative Research Centre for Plant Sciences, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut NATIONALLICENCE 700 1- Mate Colleen J. Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut NATIONALLICENCE 700 1- von Caemmerer Susanne Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut NATIONALLICENCE 700 1- Evans John R. Environmental Biology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut NATIONALLICENCE 700 1- Arvidsson Yvonne B.C. Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University PO Box 475, Canberra ACT 2601, Australia aut NATIONALLICENCE 773 0- Journal of Experimental Botany Oxford University Press 46/special_issue(1995-09), 1293-1300 0022-0957 46:special_issue<1293 1995 46 exbotj Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford