Plant Stem Cell Regulation and Floral Patterning

Outline of Research and Education

We are interested in the developmental coordination of proliferation and differentiation, and spatiotemporal-specific gene regulation in flower development. We also explore environmental response and acclimation.To reveal these molecular mechanisms, we use Arabidopsis as a model plant for genetic, reverse-genetic, biochemical and genomics approaches, especially focusing on epigenetic histone modification. We also use rice to study its conservation and diversification. Our students will work at the frontiers of plant molecular genetics, developing their research, presentation and writing skills.

Major Research Topics

Cell-cell signaling cascades controlling floral stem cell maintenance and cross-talk with transcriptional cascades

Flowers originate from self-renewing pluripotent stem cells in the floral meristems. The maintenance and differentiation of stem cells are regulated by a well-coordinated interplay of cell-cell signaling and transcriptional events. In flower development, the expression of the stem cell determinant WUS is terminated by multiple pathways. We study the cross-talk of multiple feedback pathways controlling WUS expression and reveal the molecular basis of developmental coordination (Fig.1).

Transcriptional cascades controlling floral stem cell termination

Floral stem cell termination is regulated by a multi-step process mediated by at least four transcription factors (Fig.2). AG’s function in the meristem determinacy is mediated mainly by KNU and CRC as the direct targets. SUP regulates the meristem determinacy independent of AG. We study how KNU, CRC and SUP regulate floral stem cell activities and reveal the mechanisms of spatiotemporal-specific gene regulation.

Environmental response and acclimation

We study how plants memorize environmental temperature and light conditions and reveal the molecular mechanisms that confer the plasticity and robustness of the cascades under various environmental stimuli. These studies will serve as the basis of plant growth optimization for better yields of crop plants (Fig.3).



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Fig. 1 Arabidopsis flower development .Plants maintain the pluripotent and self-renewal stem cells in the meristems. While the shoot apical meristem is indeterminate, the floral meristem activities are terminated during flower development. The stem cell determinant WUS is negatively regulated by two feedback pathways.
Fig. 1 Arabidopsis flower development
In flower development, the stem cell activities in the floral meristem are terminated (determinate), while the shoot apical meristem continues to grow.
Fig. 2 Approaches for flower developmental study.From a series of analyses, we will reveal the molecular mechanisms of spatio-temporal-specific gene regulation. We will work on the molecular interaction between DNA binding transcription factors and histone modifying enzymes at cellular levels. We also try to understand the robustness and plasticity of the flower developmental network under various growth conditions.
Fig. 2 Floral stem cell termination.
The double mutant of sup and ag shows an enlarged flower with a fasciated meristem in the center. The crc knu double mutant has a shoot inside the carpels.
Fig. 3 Plant growth optimization.By revealing the mechanisms of floral stem cell regulation and environmental responses, we will develop a molecular basis for plant growth optimization for higher crop yield.
Fig. 3 Plant growth optimization
By revealing the mechanisms of floral stem cell regulation and environmental responses, we will develop a molecular basis for plant growth optimization for higher crop yield.
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