Vegetative cells begin sporulation when a key nutrient- carbon or nitrogen source becomes scarce.

TLS Online TPP Program

#Id: 10258

#Unit 6. System Physiology – Plant

ABA is transported by both the xylem and the phloem, but it is normally much more abundant in the phloem sap

TLS Online TPP Program

#Id: 10259

#Unit 6. System Physiology – Plant

ABA synthesized in the roots can also be transported to the shoot via the xylem. The concentration of ABA in the xylem sap of well-watered sunflower plants is between 1.0 and 15.0 nM, the ABA concentration in water stressed sunflower plants increases to as much as 3000 Nm (3.0 μM)

TLS Online TPP Program

#Id: 10260

#Unit 6. System Physiology – Plant

As the soil dried out, the water potential of the leaf decreased, and the ABA content and stomatal resistance increased. The process was reversed by rewatering.

TLS Online TPP Program

#Id: 10261

#Unit 6. System Physiology – Plant

Dehydrating conditions, however, the growth of the roots is much higher in the wild type than in the ABA deficient mutant

TLS Online TPP Program

#Id: 10262

#Unit 6. System Physiology – Plant

Dehydration triggers de novo production of ABA, which in turn induces expression of stress‐related genes

TLS Online TPP Program

#Id: 10263

#Unit 6. System Physiology – Plant

ABRE PyACGTGGC & coupling element (CE) is a major cis‐acting element in ABA responsive gene expression. 

The basic leucine zipper (bZIP) transcription factors AREB and ABF can bind to the ABRE cisacting element to activate ABA‐dependent gene expression