Devonian- First amphibian and first seed plant appear

TLS Online TPP Program

#Id: 9735

#Unit 6. System Physiology – Plant

Members of the Brassicales produce glucosinolates—sulfur-containing organic compounds derived from glucose and an amino acid—as their major defensive secondary metabolites

TLS Online TPP Program

#Id: 9736

#Unit 6. System Physiology – Plant

The hydrolyzing enzyme, myrosinase (a thioglucosidase), is stored in different cells than its substrates. While myrosinase-containing cells are mostly glucosinolate-free, the so-called sulfur-rich cells (or S-cells) contain high concentrations of glucosinolates.

TLS Online TPP Program

#Id: 9737

#Unit 6. System Physiology – Plant

Sinigrin, a major glucosinolate of black mustard seeds and horseradish roots.

TLS Online TPP Program

#Id: 9738

#Unit 6. System Physiology – Plant

Members of the Poaceae family use benzoxazinoids an alkaloids derived from tryptophan as constitutively produced defensive secondary metabolites. 

TLS Online TPP Program

#Id: 9739

#Unit 6. System Physiology – Plant

Benzoxazinoids, especially 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and its derivative 2,4-dihydroxy-7-methoxy-1,4-benzoxazin- 3-one (DIMBOA), are usually stored in the vacuole as glycosides coupled to d-glucose.

TLS Online TPP Program

#Id: 9740

#Unit 6. System Physiology – Plant

Cyanogenic glycosides represent a particularly toxic class of N-containing secondary metabolites. 

Upon tissue damage, these glycosides break down and release hydrogen cyanide (HCN).