| Abstract Detail
Photosynthesis(Carbon) duanmu, deqiang [1], Spalding, Martin [2]. Suppressors of pmp1/ad1 in Chlamydomonas reinhardtii. An active CO2 concentrating mechanism (CCM) is induced when Chlamydomonas reinhardtii acclimates to limiting Ci, either low CO2 (air level; ~0.04% CO2) or very low CO2 (~0.01% CO2) conditions. Allelic mutants pmp1 and ad1, which are defective in the limiting-CO2-inducible, plastid localized LCIB, can grow in high CO2 or very low CO2 conditions but die in low CO2, indicating a deficiency in a low-CO2-specific Ci transport system. To further understand the functions and regulation of LCIB, we used insertional mutagenesis to identify suppressors of pmp1 and ad1 that can grow in low CO2. Four independent suppressors (3 for pmp1 and 1 for ad1) were selected. Genetic analysis of 3 pmp1 suppressors identified 2 allelic, dominant suppressors (su4, su5), and one recessive suppressor (su1). Consistent with the suppression phenotype, the relative affinity of photosynthetic O2 evolution and the direct Ci uptake capacity in all 3 suppressor lines was substantially increased relative to pmp1 in low-CO2 acclimated cells. Interestingly, the relative affinity of su4/su5 was intermediate between su1 and pmp1. In contrast, the ad1 suppressor (sux) can grow well in low CO2 but not in very low CO2 conditions, indicating the suppressor mutation in this case could be an essential component involved in the CCM. The separation of at least three different pmp1/ad1 suppressors could suggest complex functions and regulation of LCIB. Identification of these suppressor genes could provide more clues about the roles played by LCIB in limiting Ci acclimation.
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1 - Iowa state university, Dept of Genetics, Development & Cell Biology, Ames, IA, 50011, USA
2 - Iowa state university, Dept of Genetics, Development & Cell Biology
Keywords:
Chlamydomonas
CCM; Ci transport system.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P13017
Abstract ID:2566 |
