Altered fatty acid composition confers improved drought acclimation in maize.

Drought induces alteration in membrane lipid composition in plants; however, still little is known about whether membrane lipid remodeling plays a role in plant drought acclimation, including both drought tolerance and recovery, especially in crops. Here, we imposed natural progressive drought and re-watering in 18 maize genotypes at the seedling stage, and analyzed the physiological responses, drought tolerance and drought acclimation capabilities, contents of lipids, and fatty acid compositions. The results showed that drought caused significant reductions in shoot dry weight, relative water content, Fv/Fm, total lipid content, and double bond index (DBI) in most genotypes, while re-watering partially recovered these reductions. Meanwhile, the total lipid content, fatty acid composition, and DBI were also changed obviously in response to drought and re-watering. In order to explore the relationship between membrane lipid change and plant drought response, we did a principal component analysis. The results showed that C18:3 fatty acid contributed greatly to drought tolerance, and C16:2 and C16:3 fatty acids were more responsible for drought recovery. Meanwhile, DBI showed significant positive correlations with shoot dry weight and relative water content, but a negative association with lipid peroxidation, and more importantly, DBI was important for both drought tolerance and recovery. These alterations in membrane lipid composition may facilitate increasing membrane fluidity and decreasing membrane damage, thus maintaining the high photosynthetic capability under drought. Our results suggest that lipid remodeling is important for drought tolerance and recovery in crops, and different fatty acid species have different roles in crop drought acclimation.