Drought effects on membrane lipids and photosynthetic activity in different peanut cultivars

The effects of drought on thylakoid acyl lipid composition, photosynthetic capacity (P-max), and electrolyte leakage were evaluated in two-months-old peanut cultivars (57-422, 73-30, GC 8-35) growing in a glasshouse. For lipi d studies, plants were submitted to three treatments try withholding irriga tion: control (C), mild water stress (S1), and severe water stress (S2). Co ncerning membrane and photosynthetic capacity stability, drought was impose d by polyethylene glycol (PEG 600). In the cv. 73-30 a sharp decrease in th e content of thylakoid acyl lipids was observed, already under S1 condition s, whereas cv. 57-422 was strongly affected only under S2. Cv. GC 8-35 had the lowest content of acyl lipids under control conditions, a significant i ncrease under S1 conditions, and only under S2 a decrease occurred. Thus co ncerning lipid stability, cv. 73-30 was the most sensitive. Among lipid cla sses, phospholipids and galactolipids were similarly affected, as was MGDG relatively to DGDG. Water deficit imposed by PEG induced a higher increase in electrolyte leakage in cv. 73-30 than in the other cvs. A positive relat ionship between acyl lipid concentration and membrane integrity was found i n all studied cvs. A positive association between acyl lipid concentration, membrane integrity, and P-max was found in the cvs. 57-422 and 73-30.