When excess H2O2 accumulates in the cell, catalase converts it to H2O through the reaction.

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.

TLS Online TPP Program

#Id: 10141

#Unit 6. System Physiology – Plant

TIR1 recruits AUX/ IAA proteins to the SCF -TIR1 complex in an auxin-dependent manner. Once recruited by auxin, AUX/IAA proteins are ubiquitinated by the E3 ligase activity of the SCF-TIR1 complex, which marks the protein for destruction by the 26S proteasome.