11. It functions as a plant growth regulator against the plant hormone auxin . 12. Auxin plays a central role in PIN protein polarity establishment.13. Synthesis in the leaf of a plant hormone called auxin also ceases. 14. These interactions result in a synergistic increase in auxin efflux. 15. Auxin accumulates in the cells on the shaded side.16. In particular he isolated and purified the universal growth hormone known as auxin . 17. The most important of these are auxins and cytokinins. 18. Be cautious : too much auxin can inhibit rather than enhance root formation. 19. The plant hormones ethylene and auxin are key in fruit set and development. 20. Home gardeners sometimes spray their tomatoes with an auxin to assure fruit production.
