What is the effect of IAA on cell elongation?

Process of phototropism IAA attaches to specific receptor site in the cell membranes causing the active pumping of H+ into the cell wall the influx of H+ into the cell wall causes the pH in the cell wall to fall this provides an optimum acidic environment for expansins already present in the cell wall ions move into the cell due increased permeability and water enters by osmosis the cell swells as the vacuoles get larger so the wall grows to accommodate this the cells in the shade grow whilst the cells in the light do not grow causing the bending of the shoot towards the unilateral light source as the cell matures the auxin is destroyed and pH rises so the bonds reform between the cellulose microfibrils