Lipid Composition of Zea mays Seedlings and Water Stress-Induced Changes

The imposition of a polyethylene glycol-induced osmotic stressof –1.5 MPa for 48 h on 28 d old Zea mays (cv. Style Pak)seedlings resulted in a 44% decreased stem dry weight and increasedtriglyceride levels in stem and leaf tissues; increased sterylester levels also occurred in stems. The magnitude of theseincreases was such that, on a dry weight basis, there were increasedtotal triglyceride and steryl ester levels in the seedlingsafter the 48 h applied stress. In stems the increased triglyceridelevel was evident in all of the component fatty acids examined,whereas in leaves it was associated mainly with one fatty acidcomponent, viz. linolenic acid (C18: 3). Changes in sterol levels were small but significant and largelyrestricted to the stem. Proline levels of all three tissuesincreased in response to water-stressing the seedlings and thegreatest increase also occurred in the stem tissues.