Plastid-expressed betaine aldehyde dehydrogenase gene in carrot cultured cells, roots, and leaves confers enhanced salt tolerance

    Authors

    S. Kumar; A. Dhingra;H. Daniell

    Comments

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    Abbreviated Journal Title

    Plant Physiol.

    Keywords

    CHOLINE-O-SULFATE; GLYCINE BETAINE; CHLOROPLAST GENOME; TRANSGENIC; PLANTS; STRESS TOLERANCE; TOBACCO CHLOROPLASTS; ALANINE BETAINE; RICE; PLANTS; TRANSFORMATION; PROTEIN; Plant Sciences

    Abstract

    Salinity is one of the major factors that limits geographical distribution of plants and adversely affects crop productivity and quality. We report here high-level expression of betaine aldehyde dehydrogenase (BADH) in cultured cells, roots, and leaves of carrot (Daucus carota) via plastid genetic engineering. Homoplasmic transgenic plants exhibiting high levels of salt tolerance were regenerated from bombarded cell cultures via somatic embryogenesis. Transformation efficiency of carrot somatic embryos was very high, with one transgenic event per approximately seven bombarded plates under optimal conditions. In vitro transgenic carrot cells transformed with the badh transgene were visually green in color when compared to untransformed carrot cells, and this offered a visual selection for transgenic lines. BADH enzyme activity was enhanced 8-fold in transgenic carrot cell cultures, grew 7-fold more, and accumulated 50- to 54-fold more betaine (93-101 mumol g(-1) dry weight of beta-Ala betaine and Gly betaine) than untransformed cells grown in liquid medium containing 100 mM NaCl. Transgenic carrot plants expressing BADH grew in the presence of high concentrations of NaCl (up to 400 mM), the highest level of salt tolerance reported so far among genetically modified crop plants. BADH expression was 74.8% in non-green edible parts (carrots) containing chromoplasts, and 53% in proplastids of cultured cells when compared to chloroplasts (100%) in leaves. Demonstration of plastid transformation via somatic embryogenesis utilizing non-green tissues as recipients of foreign DNA for the first time overcomes two of the major obstacles in extending this technology to important crop plants.

    Journal Title

    Plant Physiology

    Volume

    136

    Issue/Number

    1

    Publication Date

    1-1-2004

    Document Type

    Article

    Language

    English

    First Page

    2843

    Last Page

    2854

    WOS Identifier

    WOS:000223962100036

    ISSN

    0032-0889

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