Selection and characterization of nitrate reductase-deficient mutants of Nicotiana plumbaginifolia

Pelsy, F.; Gabard, J.; Cherel, I.; Meyer, C.; Marion Poll, A.; Muller, A.; Caboche, M.

Plant Cell, Tissue and Organ Culture 12(2): 231-233

1988


ISSN/ISBN: 0167-6857
DOI: 10.1007/bf00040093
Accession: 001681275

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Abstract
Mutants deficient in nitrate reductase (NR) activity arose either spontaneously or as a result of gamma ray treatment of haploid mesophyll protoplasts derived from cell culture. Chlorate resistant cells were selected and regenerated into plants. As it was difficult to grow the mutant regenerants on their own roots in the greenhouse, they were grafted onto wild-type N. tabacum. The NR mutants were chlorotic with crinkled leaves. Of the 211 mutants tested, about 34% were classed as cnx, with impaired synthesis of the Mo cofactor or its insertion in the enzyme. The remaining 76% were classed as nia, these being unable to synthesize a functional apoenzyme but able to synthesize an active Mo cofactor. The mutation was shown to be in the structural gene of the apoenzyme. The nia locus appeared to mutate easily, as about 70% of nia mutants were spontaneous (compared with 50% in cnx mutants). Each NR mutation segregated as a recessive Mendelian factor. All the nia mutants belonged to a single complementation group. However, at the nia locus intragenic complementation was observed which was either total, leading to restored NR activity, or partial. Seven complementation groups were identified for the cnx mutants, 3 of these being described for the first time in higher plants.

Selection and characterization of nitrate reductase-deficient mutants of Nicotiana plumbaginifolia