Theme leaders: Gerco Angenent (PRI) & Ben Scheres (UU)

Background

One of the Centres of excellence of NGI is the Centre for BioSystems Genomics (CBSG). The consortium aims at developing knowledge for the improvement of food and non-food crops with reduced environmental impact and enhanced consumer quality. In addition to major programs focused on potato and tomato, the researchers in the consortium use Arabidopsis as model system to unravel plant genomes and discover important agronomical traits which can be exploited in Brassica species, potato and tomato. Arabidopsis is still the model system for plants, but the upcoming completion of the genome sequences of potato and tomato will open avenues for genomics research in these major crop species. For many traits under study in CBSG there is a growing need for proteomics technologies. For instance the interaction between pathogen and host-plant relies on the interactions between pathogen-derived effectors and plant specific complexes containing resistance proteins. Also in developmental pathways, protein interactions, post-translational modifications and protein trafficking play a prominent role. These proteomics studies require a state-of-the-art proteomics infrastructure, established technologies and knowledge about the genes and gene products. In the first round of NPC already collaborative studies between CBSG1 and NPC1 have been performed. Technologies were mainly developed in the themes of NPC1, while these technologies were implemented and validated in the CBSG program. The Hotel function of NPC offered an excellent platform for interactions between NPC and CBSG.  The Associate Program Managers will strongly stimulate collaboration between researchers in the CBSG2012 Centre and their counterparts in NPC2 by challenging mutual strategies via the organization of joint workshops, progress meetings and hotel platform. Moreover, in coordination with CBSG2, NPC2 will invest significantly in “enabling technologies”. Priority is given to development and implementation of high-throughput high-definition cell sorting coordinated by the group of Scheres (UU), which will operate as an NPC hotel. This instrument will be established to operate as an ideal sample preparation system for proteomics approached on specific plant cell types from heterogeneous cell populations.

Approach

Stem cell populations that produce specific and differentiated cells are the basis for the formation of tissues and organs of multicellular organisms. In plants, these stem cells are located in so-called meristems, which should maintain their meristematic character, but also initiate cell populations with specific identities. Further differentiation and growth of the organs shape the organism. Signal transduction pathways that often start with perceiving external signals (e.g. hormones) by membrane bound receptor complexes play crucial roles in these developmental programs. Subsequently, phosphorylation of down-stream protein targets may occur and proteins are translocated to the nucleus where transcription factor complexes control gene expression. This basic mechanism of signal transduction pathways will be the central theme in our study on plant protein networks controlling meristem development in Arabidopsis. Many of the transcription factors studied by the Angenent lab in the context of shoot development and in the Scheres lab in the context of root development appear to form complexes with members of the TCP transcription factor family. These interactions couple proteins involved in pattern formation and stem cell identity to proteins involved in the regulation of cell cycle and cell growth.  Interestingly, TCP proteins also appear to act as bridges between transcription factors that define independent spatial patterning inputs. The emerging idea is that TCP proteins integrate spatial information and translate it into relevant actions: cell division and growth. This exciting coincidence allows the two labs to jointly uncover general principles of the coupling mechanism between pattern formation and growth in plants, and to define common themes in growth control. De Vries uncovered a MADS box transcription factor in a complex that is perceiving signals from external brassinosteroids.

Deliverables

• Components of MADS box complexes involved in flower formation determined
• Function of co-factors interacting with floral specific MADS box complexes unraveled
• Established cell-sorting facility for plant cell specific proteomics.
• Components of PLT and SHR/SCR complexes involved in root development determined
• Functional relevance of interactions between patterning complexes and TCP proteins known.
• Knowledge on differential protein complex formation in stem cells and daughter cells and its relevance.
• Knowledge on the functional relevance of phosphorylation of proteins involved in determining stem cell identity.
• AGL15 protein complex composition in vascular cells
• SERK1 and AGL15 complex compositions during acquisition of embryogenic competence
• Subcellular location of SERK1 and AGL15 interaction