Activation of Calcium and Calmodium-dependent protein kinase (CCaMK)

the Central regulator of plant root endosymbiosis

Sylvia Singh and Martin Parniske

presented byAshutosh Kumar & Bharati Singh

SymbiosisA chemical communication process

Research project: plant responses to sweet talk to there microbial partner.

Guideline for microbial partner

Common symbiosis pathway

Speak, friend, and enter: signalling system that promote beneficial symbiotic association in plants.

Nature Review .April 2013,vol-11

Calcium flux

Nod factor induced calcium (Ca+) in-flux followed by the efflux of chlorine(Cl-) and potassium (k+) and alkanization of cytoplasm.

These ion movement occurred within 1 minute of adding Nod factors and explained earlier observation of membrane depolarization and Ph change.

The Membrane polarization was induced wide range of nod factor concentration 10-10 to 10-7 M, with maximum induction at 10-9 and no response at 10-11 .

Calcium spiking

Oscillation in cytosolic Ca have been observed following the nod factors.The Nod factors induced ca spiking occurs with lag of approximately 10 minutes.The ca spikes are predominantly associated with the nucleus.Individual ca spikes have very rapid initial increase followed by a more gradual decline.

Calcium and Calmodulin dependent protein kinase (CCaMK)

•Component of common symbiosis pathway

•Decoder of calcium spiking

•Positioned downstream and localised in nucleus

Two different binding mechanism of CCaMK

Kinase domain Calmodulin binding domain EF hands

Ca+2

CCaMK bind ca+2 through both EF hands and calmodulin binding domain

Animal system- CaMKII

Regulation of CCaMK

S. singh, M. Parniske (2012), university of munich

Gain of function mutation of CCaMK

Threonine (T)

CCaMK – CaM binding domain – EF hands

Aspartate (D)

Isoleucine (I)

Spontaneous nodulation

Spontaneous nodulation

Tirichine, L., et al. (2006) Nature 441: 1153-1156

Based on model plants: M.truncatula, L.japonicus

Fully differentiated root cortical cells root nodule primordia

Transcriptional specificity

D.Oldroyd, (2013) ,Nature Review

Conclusion

• Mutants that are defective in the perception of nod factor can no longer host the bacteria

•Genration of calcium spike signal is compulsory for symbiosis.

•Negative regulation of CCaMk is essential to inhibit inappropriate gene expression and organogenesis

•Genetically deregulated to trigger denovo nodule formation

THANK YOU