Unravelling the molecular mechanisms of monocot embryogenesis

• Applicant: Dr. Zhongjuan Zhang
• Subject Area: Plant Cell and Developmental Biology ; Plant Genetics and Genomics
• Term: from 2018 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 399544276

Flowering plants can reiteratively generate organs throughout their life span from the primary shoot apical and root apical meristems. Both meristems are initially formed de novo during embryogenesis. One key question is how a single-celled zygote develops into a functional organism consisting of different tissues and organs. Knowledge about embryogenesis in dicotyledonous plants has tremendously advanced in the last two decades after adopting Arabidopsis thaliana as a model organism. After the first asymmetric cell division of the zygote, the small apical cell divides in an invariant pattern at the early stage and finally develops into the majority of the mature embryo and includes the two cotyledons, the shoot meristem, hypocotyl, and root. By contrast, the large basal cell contributes exclusively to root tip formation. Auxin and WUSCHEL_RELATED_HOMEOBOX (WOX) transcription factors have been found to play essential roles in patterning, such as during the formation of the apical-basal axis and initiation of meristems. Strikingly, how the embryo of monocot plants develops is still mostly unknown, even though monocot grasses encompass the world’s most important food, feed, and bioenergy crops. Compared to dicot embryo development, monocot embryogenesis has its own unique features, such as unpredictable cell division, formation of only a single cotyledon, and a root that originates from the centre of the embryo. While much has been discovered by studying Arabidopsis embryogenesis, it is currently not clear if these concepts can be directly transposed to monocot embryogenesis. Brachypodium distachyon has emerged as a new monocot model species in recent years because of its clear advantages over current crop model species regarding growth requirements, generation time, transformation, and genome size. Therefore, I propose to systematically study monocot embryogenesis in Brachypodium distachyon. By combining live imaging, modelling of key genetic interactions in time and space, transcriptome profiling, and genetics, I will try to understand how the embryo develops. Furthermore, I aim to reveal molecular similarities and divergence in tissue patterning between monocot and dicot embryogenesis by studying the function of auxin and WOX genes in Brachypodium, as well as discover the molecular networks that regulate the unique aspects of monocot embryogenesis. This will greatly increase our knowledge on early patterning events critical to set up the initial body plan in monocots, and will broaden our understanding of the biological diversity of plant early development.

• DFG Programme: Research Fellowships
• International Connection: Netherlands
• Host: Professor Dolf Weijers, Ph.D.