The Poovaiah Laboratory

Calcium Signaling in Plants

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.

 

Calcium/calmodulin-dependent protein kinase

In 1995, we cloned a chimeric calcium/calmodulin-dependent protein kinase (CCaMK) gene with a neural visinin-like calcium-binding domain.

CCaMK
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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.

CCaMK regulation
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CCaMK is a multi-functional protein kinase.  It plays a major role in plant:microbe interactions. Examples of this are bacterial and fungal symbioses.

Regulation of the Nod factor and 'Myc factor' signaling pathways
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CCaMK is involved in decoding the calcium signal during Nod (bacterial) and Myc (fungal) factor signaling, which leads to the formation of nodules and mycorrhizae. A collaborative project with Dr. Giles Oldroyd of John Innes Centre, UK, to study the functional significance of CCaMK in bacterial and fungal symbioses resulted in joint manuscripts published in Nature (Gleason, et al., Nature, 2009) and Plant Journal (Routray, et al., 2013).

More information

Publications and links to Nature publications

that describe how calcium/calmodulin-mediated signaling is involved in plant growth, plant-microbe interactions and plant defense.


Movies (click to view)

Click to view CCaMK movieThis movie shows how CCaMK is regulated by calcium and calcium/calmodulin.  In the basal state, CCaMK is autoinhibited (inactive). Once the calcium concentration increases in response to Nod or Myc factor, the visinin-like domain captures the calcium which leads to autophosphorylation and increased affinity for calmodulin. Calmodulin binding further activates CCaMK by releasing it from autoinhibition, leading to substrate phosphorylation. 

Click to view root hair movieThis movie shows Nod factor-triggered calcium changes in the root hair.  Notice dramatic changes in calcium concentration, especially in the area around the nucleus.  Red means high calcium concentration while yellow and green indicate decreasing calcium concentrations (courtesy of Dr. Giles Oldroyd of John Innes Centre, UK).

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