Chlorophyllide aOxygenase mRNA and Protein Levels Correlate with the Chlorophyll a/bRatio in Arabidopsis thaliana

Autor: Harper, Andrea, von Gesjen, Sigrid, Linford, Alicia, Peterson, Michael, Faircloth, Ruth, Thissen, Michelle, Brusslan, Judy
Zdroj: Photosynthesis Research; February 2004, Vol. 79 Issue: 2 p149-159, 11p
Abstrakt: Plants can change the size of their light harvesting complexes in response to growth at different light intensities. Although these changes are small compared to those observed in algae, their conservation in many plant species suggest they play an important role in photoacclimation. A polyclonal antibody to the C-terminus of the Arabidopsis thalianachlorophyllide aoxygenase (CAO) protein was used to determine if CAO protein levels change under three conditions which perturb chlorophyll levels. These conditions were: (1) transfer to shaded light intensity; (2) limited chlorophyll synthesis, and (3) during photoinhibition. Transfer of wild-type plants from moderate to shaded light intensity resulted in a slight reduction in the Chl a/bratio, and increases in both CAOand Lhcb1mRNA levels as well as CAO protein levels. CAO protein levels were also measured in the cch1mutant, a P642L missense mutation in the H subunit of Mg-chelatase. This mutant has reduced total Chl levels and an increased Chl a/bratio when transferred to moderate light intensity. After transfer to moderate light intensity, CAOmRNA levels decreased in the cch1mutant, and a concomitant decrease in CAO protein levels was also observed. Measurements of tetrapyrrole intermediates suggested that decreased Chl synthesis in the cch1mutant was not a result of increased feedback inhibition at higher light intensity. When wild-type plants were exposed to photoinhibitory light intensity for 3 h, total Chl levels decreased and both CAOmRNA and CAO protein levels were also reduced. These results indicate that CAO protein levels correlate with CAOmRNA levels, and suggest that changes in Chl blevels in vascular plants, are regulated, in part, at the CAOmRNA level.
Databáze: Supplemental Index
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