ABA (C15) biosynthesis takes place in chloroplasts and cytosol from C40 precursor

ABA closes stomata in response to water stress

ABA promotes root growth and inhibits shoot growth at low water potentials

TLS Online TPP Program

#Id: 10133

#Unit 6. System Physiology – Plant

ABCB19 mediates auxin movement to root tip.

ABCB4 regulates auxin levels in root hairs.

ABCB1-mediated nondirectional auxin movement in root and shoot

TLS Online TPP Program

#Id: 10134

#Unit 6. System Physiology – Plant

NPA (1-Nnaphthylphthalamic acid) and TIBA (2,3,5-triiodobenzoic acid) inhibits efflux

TLS Online TPP Program

#Id: 10135

#Unit 6. System Physiology – Plant

Cytochalasin D, an inhibitor of actin polymerization, also inhibits AUXIN efflux

TLS Online TPP Program

#Id: 10136

#Unit 6. System Physiology – Plant

Auxin-induced proton extrusion acidifies the cell wall and increases cell extension

Auxin increase the rate of proton extrusion (wall acidification), and the kinetics of proton extrusion should closely match those of auxin-induced growth.

TLS Online TPP Program

#Id: 10137

#Unit 6. System Physiology – Plant

5 Genes involved in auxin-regulated growth and development:

1. The AUX/IAA gene family

2. The SAUR gene family

3. The GH3 gene family

Stress response genes:

1. Genes encoding glutathione S-transferases

2. Genes encoding 1-aminocyclopropane-1-carboxylic

acid (ACC) synthase

TLS Online TPP Program

#Id: 10138

#Unit 6. System Physiology – Plant

In the absence of IAA, the Transcription factor, ARF, forms Inactive heterodimers with AUX/IAA proteins.