Figure 7.

Schematic model of the PL signaling pathway induced by auxin during AR formation in cucumber. NO acts downstream of auxin (IAA) to trigger PIP, PIP₂, and PA accumulation. PLD is involved in PA formation induced by NO. PLD could be activated by PIP and PIP₂ increases and/or by other NO-mediated pathways (see “Discussion” for details). PLD-derived PA induces AR formation. The solid arrow denotes the enzymatic pathway. Dashed arrows denote regulatory pathways. The question mark denotes a yet undescribed pathway for PLD activation in cucumber.