title: Magnesium deficiency results in increased suberization in endodermis and hypodermis of corn roots.
abstract: The composition of the aliphatic components of suberin in the stele and cortex of young corn (Zea mays L.) roots was determined by combined gas-liquid chromatography/mass spectrometry of the LiAlD(4) depolymerization products. omega-Hydroxy acids were shown to be the major class of the aliphatic components of both the hypodermal (35%) and endodermal (28%) polymeric materials with the dominant chain length being C(24) in the former and C(16) in the latter. Nitrobenzene oxidation of the roots generated p-hydroxybenzaldehyde and vanillin with much less syringaldehyde. Electron microscopic examination of the hypodermal and endodermal cell walls from roots of corn plants grown in a Mg(2+) -deficient (0.03 millimolar) nutrient solution showed that these walls were more heavily suberized than the analogous walls of roots from plants grown in normal (2 millimolar) Mg(2+) levels. Analysis of the LiAlD(4) depolymerization products of the suberin polymers from these roots showed that the roots grown in low Mg(2+) had 3.5 times as much aliphatic suberin monomers on a weight basis as the roots from plants grown in nutrient with normal Mg(2+) levels. Roots from plants grown in Mg(2+) -deficient nutrient solution released 3.8 times the amount of aromatic aldehydes upon nitrobenzene oxidation as that released from normal roots. As the degree of Mg(2+) deficiency of the nutrient solution was increased, there was an increase in the aliphatic and aromatic components characteristic of suberin. Thus, both ultrastructural and chemical evidence strongly suggested that Mg(2+) deficiency resulted in increased suberization of the cell walls of both hypodermis and endodermis of Zea mays roots. The roots from Mg(2+) -deficient plants also had a higher amount of peroxidase activity when compared to control roots.
authors: Instituto De Edafologia y Biologia Vegetal, Madrid, Spain.
authors: J M
authors: JM
authors: Pozuelo
authors: K E
authors: KE
authors: Espelie
authors: P E
authors: PE
authors: Kolattukudy