Table 1.

Rboh multiregulation in vegetative tissues vs. the pollen tube.

	Vegetative tissues	Pollen tube	Modulation
Ca2+	Direct binding to EF hands motifs Indirectly: Ca2+-induced phosphorylation; binding to Rop-GTPase	Synergistic activation
Phosphorylation	CPK5 CIPK26 MAPK cascades	Unidentified candidates (pollen tube CPK proposed)	Synergistic activation
Small GTPases	Rac1 Rop2	Rop1 Rac5	Activation Targeting?
Low abundance of signaling phospholipids	PA produced by PLDα1	PA (synergism with Ca2+) PIP2	Activation
NO	S-nitrosylation	Putative, not described	Negative