Two Mechanisms Down-Regulate Signaling from RTKs

1. Phosphotyrosine phosphatases

2. Receptor-mediated endocytosis followed by degradation in lysosomes

TLS Online TPP Program

#Id: 10236

#Unit 6. System Physiology – Plant

DE-ETIOLATED2 (DET2) gene, which encodes a brassinosteroid biosynthetic gene. Det2 loss-of-function mutants have reduced levels of brassinosteroids, resulting in a de-etiolated appearance of the seedling even when grown in the dark

TLS Online TPP Program

#Id: 10237

#Unit 6. System Physiology – Plant

Brassinosteroids are also required for promotion of cell

elongation by gibberellins, and gibberellin-induced degradation

of the DELLA repressor enhances the brassinosteroid response.

TLS Online TPP Program

#Id: 10238

#Unit 6. System Physiology – Plant

OsGSR1, a member of the gibberellic acid–stimulated gene family, acts as a positive regulator of both the gibberellic acid response and brassinosteroid biosynthesis.

TLS Online TPP Program

#Id: 10239

#Unit 6. System Physiology – Plant

ABA was originally thought to induce abscission, however, abscission is regulated by ethylene rather than ABA.

TLS Online TPP Program

#Id: 10240

#Unit 6. System Physiology – Plant

ABA has a single chiral center at C‐1′. Only the (S)‐enantiomer occurs in nature

TLS Online TPP Program

#Id: 10241

#Unit 6. System Physiology – Plant

ABA is synthesized in almost all cells that contain chloroplasts

or amyloplasts and has been detected in every major organ and tissue. ABA is a 15-carbon terpenoid, or sesquiterpenoid, which is synthesized in plants by an indirect pathway via 40-carbon carotenoid intermediates