#Question id: 12525

The role of ABA signaling during water stress in the guard cells in presence and absence of ABA;

a) Anion effl¬ux leads to depolarization of the plasma membrane, which drives K+ effl¬ux. The eff¬lux of ions (A– and K+) reduces the turgor pressure of guard cells, resulting in stomatal closure.

b) Both OST1 and CPKs phosphorylate and thereby activate plasma membrane anion channels, leading to ef¬flux of anions (A–). But  this process can be inhibited directly by PP2Cs 

c) Inhibition of PP2C activity releases the positive regulator kinase OST1 from inhibition, resulting in both phosphorylation and activation of NADPH oxidases (RBOHs)

d) RBOHs catalyze the formation of apoplastic reactive oxygen species (ROS),  which triggers opening of plasma membrane Ca2+-permeable ion channels 

e) The resulting elevation of cytosolic Ca2+ leads to activation of calcium-dependent protein kinases (CPKs), which can also activates the RBOH proteins further promoting Ca2+ infl¬ux into the cytosol.

Which statements belongs to the presence and absence of ABA during signalling;

I. In presence of  ABA

II. In absence of ABA

Which of the following combination from the given above statements is correct?