Laboratories

Plant Developmental Signaling

Outline of Research and Education

Microscopic observation of plant sections allows one to realize the beautiful patterns of cells, each with a different shape and size (Fig. 1). These cells are not only diverse in appearance, but are functionally specialized to play specific roles in each organ. These tissue patterns are produced from a single cell, the zygote. One of the most fundamental questions in plant developmental biology is how complex plant structures are derived from a single cell.

Our research group is trying to identify basic principles of plant development using model plant species. We aim to understand both intercellular and intracellular signal transduction pathways underlying the pattern formation and cell differentiation of roots and embryos, as well as cell reprogramming that triggers embryogenesis.

Major Research Topics

Cell-cell communication in tissue patterning.

Due to the presence of rigid cell walls, plant cells are generally unable to alter their direction or position in the organ primordia. Therefore, timing and orientation of cell divisions, as well as cell fates, are determined by interpreting the positional cues of surrounding cells. Such developmental mechanisms rely on the presence of intimate cell-cell communication pathways. Our recent studies have revealed the presence of novel signaling pathways that allow regulatory molecules such as transcription factors and microRNAs to travel from cell to cell (Fig. 2). We are currently focusing on the generality of such cell-cell signaling pathway in root and embryo patterning.

Cell reprogramming and pattern formation during embryogenesis and germ cell formation

Embryogenesis of the Brassica family, including the model plant Arabidopsis, proceeds in a highly coordinated manner (Fig.3). Similar to innovation of iPS cells, activation of an embryo- and germ cell-specific developmental program is initiated only after the reprogramming of somatic cells to the embryonic status. We have recently discovered a key reprogramming factor in Arabidopsis and bryophytes, and are currently investigating their mechanism of action. We are also constructing a translational approach that utilizes this reprogramming factor to propagate useful plant lines without waiting for the transition to the reproductive growth phase.

References

  1. Nakajima et al., Nature, 413, 307-311, 2001
  2. Nakajima et al., Plant Cell, 16, 1178-1190, 2004
  3. Sarkar et al., Nature, 446, 811-814, 2007
  4. Miyashima et al., Plant Cell Physiol., 50, 626-634, 2009
  5. Miyashima et al., Development, 138, 2303-2313, 2011
  6. Waki et al., Curr. Biol., 21, 1277-1281, 2011
  7. Waki et al. Plant J., 73, 357-367, 2013
  8. Miyashima et al., Plant Cell Physiol., 54, 375-384, 2013
  9. Hisanaga et al., Curr. Opin. Plant Biol., 21, 37-42, 2014
  10. Koi et al., Curr. Biol., 26, 1775-1781, 2016
Fig. 1 (Left) In leaves, specialized cell types such as mesophyll, stomata, and vascular cells, are spatially arranged to maximize photosynthetic ability. (Right) Root tissues are organized into a concentric pattern that facilitates water and nutrient uptake, as well as their metabolism and translocation.
Fig. 1 (Left) In leaves, specialized cell types such as mesophyll, stomata, and vascular cells, are spatially arranged to maximize photosynthetic ability. (Right) Root tissues are organized into a concentric pattern that facilitates water and nutrient uptake, as well as their metabolism and translocation.
Fig. 2 Plant cells are connected with a cytoplasmic continuum termed plasmodesmata (PD). PD allows passage of regulatory molecules, such as transcription factors and small RNAs, thereby serving as a channel to transmit developmental signals.
Fig. 2 Plant cells are connected with a cytoplasmic continuum termed plasmodesmata (PD). PD allows passage of regulatory molecules, such as transcription factors and small RNAs, thereby serving as a channel to transmit developmental signals.
Fig. 3 Pattern formation in embryogenesis is triggered by cell reprogramming and proceeds in a highly ordered manner. We study the mechanisms underlying embryonic pattern formation and reprogramming, as well as application of the reprogramming factor for efficient propagation of useful plants.
Fig. 3 Pattern formation in embryogenesis is triggered by cell reprogramming and proceeds in a highly ordered manner. We study the mechanisms underlying embryonic pattern formation and reprogramming, as well as application of the reprogramming factor for efficient propagation of useful plants.
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