G-Proteins as Molecular Switches in Signal Transduction - PAMP Signals in Plant Innate Immunity: Signal Perception and Transduction - page 180

PAMP signal

Activation

Rac GTPases Rboh

Modulation of
Ca 2+ influx

Regulation

Rac GTPase RBOH

interaction

-

Cytosolic Ca 2+

Activation

NADPH oxidase activity

ROS production

Fig. 3.5 Interplay between Rac GTPases - RBOHs - cytosolic calcium transient in ROS generation

and the phospholipases are involved in ROS generation (Laxalt et al. 2007 ; Guo
et al. 2012 ). Heterotrimeric G protein

-subunit regulates PLD through a motif anal-
ogous to the DRY motif in G-protein-coupled receptors in Arabidopsis (Zhao and
Wang 2004 ). The activated PLD hydrolyzes phospholipids to produce the lipid
second messenger PA (Zhao and Wang 2004 ).
PA has been shown to be able to trigger an oxidative burst (Sang et al. 2001 ; Park
et al. 2004 ). PA is involved in the activation of NADPH oxidase and ROS is
generated through the action of NADPH oxidase (Laxalt et al. 2007 ). PA directly
activates NADPH oxidase by interacting with the enzyme components (Palicz et al.
2001 ). It promotes superoxide-generating activity in plants through the activation of

α