Exogenous auxin effects on growth and phenotype of normal and hairy roots of Pueraria lobata (Willd.) Ohwi
2002
Liu, C. | Zhu, J. | Liu, Z. | Li, L. | Pan, R. | Jin, L.
Pueraria lobata hairy roots have faster elongation and more branches than normal roots. The responses of hairy roots and normal roots to treatment with three auxins, indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and naphthalene acetic acid (NAA) were different. In normal roots, all three auxins strongly stimulated lateral root formation at all tested concentrations. Responses to IAA and IBA in primary root growth and lateral root elongation were similar and depended on concentration; promotion at 0.1 micromolar, no effect at 1.0 micromolar, and inhibition at 2.5 micromolar. In hairy roots, lateral root formation varied in response to the different auxins, i.e. depressed by NAA, unaffected by IAA, and promoted by IBA. Primary root growth was slightly inhibited by IBA and was unaffected by IAA. However, mean lateral root length was reduced in response to IAA and IBA. Only NAA exerted strong inhibition on primary and lateral root elongation in both root types. The similar free IAA and conjugated IAA content but quite different basal ethylene production and biosynthesis in hairy and normal roots suggested different mechanisms of response to exogenous auxins in the two root types.
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