Lecture will be held in English

Hosted by

Karel Říha

About the lecture

De novo Development of Polarity and the Generation of Stem Cell Niches

The multicellular bodies of plants develop from single cells; the multicellular diploid phase of the plant life cycle develops from a polarised zygote, and the multicellular haploid phase develops from a spore without polarity. Each of these cell types divide to form masses of cells – enclosed embryos and free-living sporelings respectively. These cell masses form meristems, generative centres from which the body of the plant develops. In bryophytes, meristems develop in both diploid multicellular embryos and haploid sporelings. Our laboratory investigates mechanisms that transform the non-polar spore into a polarised cell in the liverwort Marchantia polymorpha.

The spore of is produced by meiosis and the mature spore lacks any markers of polarity. Upon germination, the spore polarizes de novo. This polarity orients the first cell division, which is asymmetric and produces a larger cell on apical side and a smaller cell on the basal side. The apical cell functions as a regenerative stem cell while the basal cell differentiates as a rhizoid cell. Therefore, the polarity that develops in the germinating spore determines where the first two cell form and their developmental fates. Preliminary data indicate that light polarises the spore cell and orients the cell plate during the first asymmetric cell division. At the two-cell stage, the transcription factor ROOT HAIRLESS SIX-LIKE promotes the differentiation of the basal cell as a rhizoid cell. A stem cell niche develops from which the plant body develops is cells derived from the apical cell.

Recent data on mechanism that operates during the development of cell polarity and the formation of the stem cell niche will be presented.

References

1. Streubel S, Deiber S, Rötzer J, Mosiolek M, Jandrasits K, Dolan L Meristem dormancy in a dichotomous branching system is regulated by a liverwort-specific miRNA and a clade III SPL gene in Marchantia polymorpha Current Biology 2023. 33, 1–15.

Acknowledgements

This research is funded by a European Research Council Advanced grant, an Austrian Academy of Sciences fellowship, a BBSRC studentship and a studentship from MoA Technology Ltd.

Registration for lunch with the speaker /for Ph.D. students/

The sponsored lunch usually takes place in the Campus River restaurant. Please meet the speaker and other students at 12:45 at the reception desk at the main entrance (building B22, see the map below).