Genetic analysis of nitrate reductase deficient mutants of nicotiana plumbaginifolia evidence for six complementation groups among 70 classified molybdenum cofactor deficient mutants

Gabard, J.; Pelsy, F.; Marion Poll, A.; Caboche, M.; Saalbach, I.; Grafe, R.; Mueller, A.J.

Molecular and General Genetics 213(2-3): 206-213

1988


DOI: 10.1007/bf00339583
Accession: 005511254

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Abstract
A total of 70 cnx mutants have been characterized from a collection of 211 nitrate reductase deficient (NR-) mutants isolated from mutagenized Nicotiana plumbaginifolia protoplast cultures after chlorate selection and regeneration into plants. They are presumed to be affected in the biosynthesis of the molybdenum cofactor since they are also deficient for xanthine dehydrogenase activity but contain NR apoenzyme. The remaining clones were classified as nia mutants. Sexual crosses performed between cnx mutants allowed them to be classified into six independent complementation groups. Mutants representative of these complementation groups were used for somatic hybridization experiment with the already characterized N. plumbaginifolia mutants NX1, NX24, NX23 and CNX103 belonging to the complementation groups cnxA, B, C and D respectively. On the basis of genetic analysis and somatic hybridization experiments, two new complementation groups, cnxE and F, not previously described in higher plants, were characterized. Unphysiologically high levels of molybdate can restore the NR activity of cnxA mutant seedlings in vivo, but cannot restore NR activity to any mutant from the other cnx complementation groups.

Genetic analysis of nitrate reductase deficient mutants of nicotiana plumbaginifolia evidence for six complementation groups among 70 classified molybdenum cofactor deficient mutants