APPENDIX - A NOVEL TYPE OF HOMEOTIC MUTATION AFFECTING FLORAL MORPHOLOGY

A mutant with altered floral morphology, designated Appendix, was observed among the progeny of a regenerated transgenic tobacco (Nicotiana tabacum) plant. Appendix flowers had small outgrowths resembling pistils on the tips of fertile anthers. No obvious morphological changes could be seen in any other part of the plant. A more careful analysis using histological methods and scanning electron microscopy revealed that the outgrowths were composed only of a style and a stigma and that these added organs can support pollen germination and pollen tube growth. Examination of anther ontogeny using scanning electron microscopy indicated that the anther style and stigma of the Appendix mutant developed from a small group of cells at the anther tip coincident with development of the carpel style and stigma. Genetic analysis indicated that this mutation is nuclear, recessive and linked to the 'transferred DNA' (T-DNA) inserted during the generation of transgenic plants using Agrobacterium tumefaciens. The Appendix phenotype does not correspond to any of the other types of floral homeotic mutations that have been described so far.