Bhatia Group

Cellular and molecular frameworks of multi-faceted actions of cytokinin

Cytokinins (CKs) are a class of plant hormones that are fundamental to plant development and are conventionally considered to promote cell division in plant aerial organs. However, recent findings suggest that, surprisingly, CKs can also promote cellular differentiation and expansion in aerial organs, in a stage-dependent manner. Therefore, the roles of CKs in shaping plant aerial organs are much more diverse than previously thought. How CKs regulate and coordinate cell proliferation and differentiation decisions during development remains largely unclear. 

By integrating genetic analyses including genetic mosaics, quantitative live imaging, and single cell omics, we are exploring multi-faceted roles of CKs in plant development, using Arabidopsis thaliana leaves as model.

Specifically, we are focusing on

• How CKs regulate cell proliferation and differentiation and
• How are these distinct cellular effects coordinated in space and time during aerial organ development

Our key questions are:

• How are CK metabolic and signaling genes patterned during leaf development?
• What are the relative roles of CK mediated proliferation and differentiation in leaf development?
• What is the range of CK action in regulating cell proliferation and differentiation?
• What are the diverse genetic pathways underlying multiple facets of CK action?

Cytokinin patterning during leaf development

We will explore the spatiotemporal distribution of CK signaling, synthesis and catabolism during leaf development. This is a challenging endeavor as CK has diverse cellular effects at different stages of organ development. We aim to capture spatiotemporal expression patterns of genes involved in CK signaling, synthesis, response, and degradation during leaf development at cellular resolution.

Role of cytokinin mediated proliferation and differentiation in leaf development

We are working to develop a quantitative understanding of how CK controls the amount and duration of cellular growth and proliferation during leaf development. We will use a combination of time-lapse imaging and cell-fate mapping to capture cellular growth dynamics and compute cellular growth patterns in A. thaliana leaves with genetic and transgene based increased and decreased CK function, in relation to wild type. We aim to develop a growth-based framework of CK action in leaf development. Further, by using a genetic mosaics approach, we are also investigating the range of CK action in regulating cell proliferation and differentiation during leaf morphogenesis. 
 

Time-lapse imaging and cell fate mapping to quantify cellular growth patterns in Arabidopsis thaliana leaves.

Genetic pathways underlying multiple facets of cytokinin action

Cell proliferation and differentiation are two distinct developmental processes mediated by CK. Transitioning from cell proliferation to differentiation is an important development decision that must be coordinated in space and time. One possible mechanism through which CK may mediate this coordination is via altering the genetic pathways to promote proliferation and differentiation, at the right time during development.

In order to understand how CK orchestrates cell proliferation and differentiation during development, we will use use a comparative single-nucleus (sn) multiome approach to explore:

• The transcriptomic signatures underlying two distinct developmental decisions mediated by CK, and
• Diverse gene regulatory logic in single cells undergoing different developmental decisions in response to CK

Join or collaborate with the Bhatia Group

If you're interested in investigating the mechanistic basis of the function of the plant hormone cytokinin (CK) in plant development using Arabidopsis thaliana as model, and would like to discuss the positions or opportunities to collaborate, please get in touch with Neha Bhatia via email.