|Ortiz, Guadalupe - PLANT BIO UOFI URB IL|
Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: April 28, 1996
Publication Date: N/A
Technical Abstract: Genetic analysis of a mutant of Arabidopsis thaliana that, under low irradiance is apparently incapable of thioredoxin-dependent reduction/activation of the CF-ATP complex (Gabrys' et al. 1094, Plant Physiol.104:769-776), indicates a nuclear mutation with incomplete dominance of the wild type allele. Incubation of dark-adapted wild type and mutant leaves with DTT, resulted in complete reduction of the chloroplast coupling factor of wild type leaves and in only marginal reduction of the mutant leaves. Similar behavior was found in isolated thylakoids from wild type and mutant leaves implicating an alteration in the ATP synthase y-subunit. The gene of the CF-y subunit (atpC1) of the mutant was subsequently cloned and sequenced. The DNA sequenced showed that an adenine was changed for guanine producing a change in a highly conserved glutamic acid (Flu-224) for Lys. The mutation eliminates a Taq I restriction site. All the plants from F2 and F3 generation showing wild type phenotype have the wild type sequence of the atpC1. All the plants from F2 and F3 generation showing mutant phenotype lost the same Taq I site. More than 70 percent of plants with intermediate phenotype have both, wild type and mutant sequences. These results indicate that the alteration of the 518 nm relaxation kinetics in the mutant is caused by the single change in the y-subunit gene. This work was supported in part by a grant from the USDA NRI program (grant No. 91-37100-6620).