Abstract
The 6b gene is one of the tumourigenic genes of Agrobacterium tumefaciens, and causes morphological alterations, and reduced polar auxin transport. To investigate the relationship between endogenous auxin localization and cotyledonous morphology, we introduced to tobacco the AK-6b gene under the control of dexamethasone (Dex) inducible promoter. The seeds of T1 generation were sowed on MS medium containing Dex, and the seedlings were collected over time. Tissue sections were made and subjected to anatomical study or treated with the monoclonal antibody against indoleacetic acid (IAA). Analysis of the transverse sections indicated that the morphological alteration was recognized on the abaxial side of the cotyledons at 7 days after sowing. IAA was found to be equally distributed over cotyledons as long as 5 days. However, preferential localization was recognized on the abaxial side at 6-7 days. Therefore, it is suggested that the morphological alterations and the auxin localization are closely associated.
