Study of phytohormone kinetin effect on free fatty acids composition in maize plants under hypoxic stress by gas-liquid chromatography method

Abstract

Effect of phytohormone kinetin on composition change of free fatty acids of maize plants under different
aeration (air, hypoxia, CO₂-media) was studied. Free fatty acids were extracted after transfer to potassium
salts. By gas-liquid chromatography method it was discovered that maize seedlings contain almost all
free fatty acids specific to phospholipids of plant cells. An exception was oleic acid which was detected in
trace amount. The dominating ones among free fatty acids of maize seedlings were saturated C16:0 palmitic
and unsaturated C16:1 palmitoleic acids (23.5 and 16.11% respectively). Plant treatment by kinetin induced
changes among free fatty acids of seedlings but did not affect their qualitative composition. Under hypoxia
and especially under CO₂-media the accumulation of unsaturated fatty acids (palmitoleic and linoleic) was
observed which resulted in increase of their unsaturation level (u/s) from 0.57 to 0.60 and 0.79 respectively.
Pre-treatment by kinetin prevented the observed changes in free fatty acids content in plants placed under
modified gas media and largely limited linoleic acid accumulation. At the same time under kinetin the content of monoenoic unsaturated fatty acids was increasing. This resulted in decrease of unsaturated free fatty acids (u/s) till 0.60 and 0.54 which was close to aerated plants.
We showed that kinetin prevents degradation of phospholipids, free fatty acids accumulation and
their peroxidation which were only assumptions before. It is necessary to note that stabilizing effect of kinetin was observed in seedlings under normal hypoxia and under high concentrations of carbon dioxide. This fact shows that effect of high concentrations of carbon dioxide on fatty acids exchange is easily reversible and can be cancelled by kinetin treatment of plants or return to normal aeration. Assumed that phytohormone kinetin can inhibit a breakdown of phospholipids and their peroxidation which increases tolerance of seedlings to hypoxia and CO₂-media.