Quantitative character- large number of possible phenotypes that are not easily distinguished

TLS Online TPP Program

#Id: 7531

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 7532

#Unit 6. System Physiology – Plant

According to the current hypothesis, the gradient in phototropin phosphorylation induces the movement of auxin to the shaded side of the coleoptile. Once the auxin reaches the shaded side of the tip, it is transported basipetally to the elongation zone, where it stimulates cell elongation. The acceleration of growth on the shaded side and the slowing of growth on the illuminated side (differential growth) give rise to the curvature toward light.

TLS Online TPP Program

#Id: 7533

#Unit 6. System Physiology – Plant

Dense plastids serve as gravity sensors

Gravity does not form gradient.

The only way of sensing gravity is through the motion of a sedimenting body.

In plants intracellular gravity sensors are large, dense amyloplast.

Statoliths –amyloplasts that function as gravity sensors.

Statocytes-specialized gravity sensing cells in which statoliths are present.

TLS Online TPP Program

#Id: 7534

#Unit 6. System Physiology – Plant

Strigolactones as signal that interact with auxin in regulating apical dominance Strigolactone is a group of trepenoids that produced in both shoots and roots and is transported through xylem

TLS Online TPP Program

#Id: 7535

#Unit 6. System Physiology – Plant

GA levels in plants are correlated with stem length, internode elongation and seed germination. Play role in seed germination, transition to flowering, and pollen development.

TLS Online TPP Program

#Id: 7536

#Unit 6. System Physiology – Plant

The biosynthesis of gibberellins is under strict genetic, developmental, and environmental control, and numerous gibberellin-deficient mutants have been isolated.  Mendel’s tall/dwarf alleles in peas are a famous example. Such mutants have been useful in elucidating the complex pathways of gibberellin biosynthesis.