The 30th International Conference on Arabidopsis Research (ICAR 2019)

569 / 2019-03-30 20:41:00

Multistep termination of floral stem cell activities

stem cells, auxin, histone modification

Plenary track > Development

In flower development, the robust stem cell activities are terminated to produce a fixed number of floral organs and eventually seeds for the next generation. In Arabidopsis, the floral stem cell activity is sustained by expression of the homeo-domain transcription factor WUSCHEL (WUS). Expression of WUS is terminated by multiple genetic pathways including the floral homeotic protein AGAMOUS (AG). In order to reveal spatio-temporal-specific regulation of floral stem cell activities, we have studied downstream activities of AG and other transcription factors by molecular genetic approaches. AG induces transcription of two transcription factors KNUCKLES (KNU) and CRABS CLAW (CRC), which function to terminate WUS. While KNU directly represses WUS, CRC controls floral meristem determinacy through the regulation of auxin homeostasis, thus repressing WUS. The zinc finger transcription factor SUPERMAN (SUP) is also involved in negative regulation of WUS. SUP is expressed at the boundary regions of stamen and carpel primordia. SUP interacts with components of Polycomb repressive complex 2 (PRC2) and fine-tunes local auxin signaling by negatively regulating the expression of the auxin biosynthesis genes YUCCA1/4 (YUC1/4). I will discuss how multiple factors spatially and temporally coordinate floral meristem determinacy.