The first visible sign of limb development is the formation of bilateral bulges called limb buds.

1. limb bud  is 

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.

TLS Online TPP Program

#Id: 10139

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 10140

#Unit 6. System Physiology – Plant

The auxin receptor is composed of two proteins: the SCF complex component TIR1 and the repressor protein AUX/IAA.