| Abstract Detail
Tuesday Morning Contributed Talks He, Chaoying [1], Saedler, Heinz [1]. The evolution of the Chinese-lantern in Physalis, a morphological novelty in Solanaceae. THE Chinese-lantern or Inflated-Calyx-Syndrome (ICS) encapsulating the Physalis berry is a morphological novelty in the Solanaceae. ICS is generated by heteroptopic expression of MPF2, which encodes a MADS-box transcription factor. RNAi experiments in Physalis and ectopic expression in Solanum suggest that MPF2 promotes sepal cell division and inhibits cell elongation. Heterotopic expression of MPF2 in Physalis pubescens is due to promoter alterations as compared to the promoter of its orthologue STMADS16 from the closely related Solanum tuberosum, which does not feature ICS. Clearly, heterotopic expression of MPF2 is not sufficient for ICS formation since signals released from the fertilization process or seed development are also important for calyx growth. Depistillation experiments suggest the importance of phytohormones, like cytokinins and gibberellins. Heterotopically expressed MPF2 generates small sepal cells, which are amplified by cytokinins; gibberellins elongate these cells, thus generating ICS. Cytokinin treatment of epidermal calyx cells seems to enhance nuclear transport of MPF2 or STMADS16 proteins. These findings are corroborated by the synthesis of ICS-like trait in transgenic Solanum tuberosum via ectopic expression of STMADS16 and treatments with cytokinin and/or gibberellin. The specificity of cytokinin action is also seen in transgenic Arabidopsis plants ectopically expressing MPF2 or STMADS16 treated with cytokinin and thus featuring inflated sepals. Recruitment of an existing transcription factor MPF2-like protein from a vegetative context, like STMADS16 in potato, to a floral context, as MPF2 in Physalis, is the important change in the evolution of ICS in Solanaceae.
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1 - Max-Planck-Institute for Plant Breeding Research, Department of Molecular Plant Genetics, Carl-von-Linne-Weg 10, Cologne, 50829, Germany
Keywords:
Chinese-lantern
Inflated-Calyx-Syndrome
Physalis
morphological novelty
MADS box genes
cytokinin
gibberellin
plant hormone
Solanaceae.
Session: SOL04-2
Location: Ballroom AB/Monona Terrace
Date: Tuesday, July 25th, 2006
Time: 8:30 AM
Abstract ID:74 |
