Forward Genetic Screen to Understand Pericycle-Endodermis Communication

Morphological changes in plant cells are driven by biochemical and physical forces. Physical forces can be external such as gravitational force, wind, soil constraints or they can be intrinsic like turgor pressure. Perceiving these forces and converting the mechanical stimuli to developmental changes is a critical feature of plant cells. Lateral root (LR) emergence is one such activity that involves complex interplay of hormones, mechanical forces and cellular reorganization. LR formation starts deep within the root tissue by asymmetrical divisions of the Xylem Pole Pericycle (XPP) cells. We have shown that XPP cells need to swell to divide and this has to be accommodated by the overlying endodermal cells via an auxin-driven signaling pathway. This is characterized by the controlled loss of cell volume to make way for the growing LR. Blocking auxin response in the endodermis, affects both initiation in the XPP and growth through the endodermis, thereby completely blocking LR formation. We aim to identify novel factors involved in the communication between XPP and endodermal cells by carrying out a forward genetic screen on the Arabidopsis thaliana DR5_pro::nls3nVenus / CASP1_pro::shy2-2 line where LR formation is completely blocked due to impaired endodermal auxin signaling. The mutants are screened for fully emerged LRs or primordia that are unable to traverse the endodermal barrier. Preliminary results from this screening process will be presented.