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Research

Areas of Specialization

The primary emphasis of our research is on calcium/calmodulin-mediated signaling and its role in plant growth and plant response to the environment. Specifically, we are investigating the role of calmodulin and its binding proteins in calcium-mediated signaling.

Illustration of calmodulin with four calcium-binding sites

Calcium/calmodulin-dependent protein kinase (CCaMK)

Illustration of domains of Calcium/calmodulin-dependent protein kinase (CCaMK)

The structure of CCaMK is characterized by the presence of a catalytic domain, a calmodulin-binding domain, and a visinin-like calcium-binding domain in a single polypeptide; making it distinctly different from other known plant and animal kinases. Biochemical characterization of CCaMK revealed that it is regulated by both calcium and calcium/calmodulin (see Selected Publications).  Below is a schematic illustrating how calcium and calmodulin are involved in its regulation.

Illustration of how calcium and calmodulin are involved in regulation of Calcium/calmodulin-dependent protein kinase (CCaMK)

CCaMK is a multi-functional protein kinase.  It plays a major role in bacterial and fungal symbioses. CCaMK is involved in decoding the calcium signal during bacterial (Nod factor) and fungal (Myc factor) symbioses, leading to the formation of nodules and mycorrhizae.

The figure below illustrates the unique roles of CCaMK during bacterial and fungal symbioses.

Illustration of a plant symbiotic signaling pathway
Plant symbiotic signaling pathway (Poovaiah and Du. 2018. “Calcium signaling:  Decoding mechanism of calcium signatures.” New Phytologist, 217:1598-1609).

Figures below illustrate the role of calcium/calmodulin in plant defense/immunity with an emphasis on AtSR1/CAMTA3.

Illustration of calcium/calmodulin in plant defense/immunity with an emphasis on AtSR1/CAMTA3

Continued: Illustration of calcium/calmodulin in plant defense/immunity with an emphasis on AtSR1/CAMTA3

A model Illustrating AtSR1 as a negative regulator of salicylic acid activation pathway and a guardee (Yuan, P., Tanaka, K., Du, L. and Poovaiah, B.W. 2018 “Calcium signaling in plant autoimmunity:  A guard model for AtSR1/CAMTA3-mediated immune response.” Molecular Plant 11, 637-639).

Illustration of perception and feed-in steps of Ca2+ signals in the regulatory network of plant immunity

Perception and feed-in steps of Ca2+ signals in the regulatory network of plant immunity (Yuan, P., Jauregui, E., Du, L., Tanaka, K. and Poovaiah, B.W. 2017. “Calcium signatures and signaling events orchestrate plant-microbe interactions.” Curr. Opin. in Plant Biol. 38:173-183).