Phenotypic characterization of a tobacco mutant impaired in auxin polar transport |
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Authors: | M Naderi A Caplan P H Berger |
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Institution: | (1) Department of Plant, Soil and Entomological Sciences, Division of Plant Pathology, University of Idaho, Moscow, ID 83844-2339, USA, US;(2) Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow, ID 83844, USA, US |
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Abstract: | A mutation in tobacco (Nicotiana tabacum L. cv `Xanthi') called lat (low auxin transport) that changes many morphogenic features throughout the life of the plant has been isolated. Abnormalities
were observed in seed development, embryogenesis, cotyledon formation, leaf initiation and development, leaf veination pattern,
and flower development. Selfed R2
lat mutant plants set between 60% and 90% fewer seeds than wild-type tobacco, and about 10% of these seeds did not germinate.
Non-germinating seeds contained either abnormal embryos or abnormal endosperm tissues. There was no uniformity in the stage
at which embryonic development ceased in the aberrant seeds. Seedlings often revealed abnormal and highly varied phenotypes
after germination. In some of these cases, cotyledons were heart-shaped, fused, cup-shaped, or cylindrical. Leaf morphology
ranged from normal to cup-shaped, and some leaves occasionally produced shoots from the leaf midvein. Flowers ranged from
normal to compound with occasional fused floral parts or split petals. Stamens were sometimes petal-like. This unusual assortment
of phenotypic changes suggested that the mutation might affect a basic component of plant metabolism. We found that polar
transport of indole-3-acetic acid (IAA) was reduced to about 9–19% of the wild-type level in the inflorescence axis of selfed
R2
lat mutants. In addition, supplementation of 1-naphthaleneacetic acid (NAA) to sterile media suppressed some of the abnormalities
of the lat mutation so long as the plants grew there. Similarities in the phenotype of embryos, cotyledon and leaf shapes, translocation
of labeled IAA, and response to applied NAA indicate that the lat locus of tobacco may be analogous to the pin locus of Arabidopsis, or produce a protein that functions in the same auxin-transport pathway.
Received: 18 March 1997 / Revision received: 1 May 1997 / Accepted: 17 June 1997 |
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Keywords: | Tobacco Nicotiana tobacum Mutation Auxin transport Indole acetic acid |
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