Figure 8.

Proposed Role of HIL1 in Leaf MGDG Turnover under Heat Stress.

34:6-MGDG is synthesized in the prokaryotic pathway and by fatty acid desaturases (FAD). HIL1 is responsible for the release of 18:3-FFA from 34:6-MGDG in chloroplasts. Other lipases of DAD1-like proteins and patatin-like lipid acyl hydrolases could also work in this process. The released 18:3-FFA is converted to 36:6-PC and 54:9-TAG in the endoplasmic reticulum (ER). Red arrows indicate the increased pathways under heat stress suggested from the lipidomic analysis in this study and the transcriptome analysis (Higashi et al., 2015), whereas blue arrows indicate the decreased pathways under heat stress. To improve thylakoid membrane stability, HIL1 may coordinately work with the coexpressed gene encoding DGD1. DGD1 synthesizes DGDG from MGDG (Dörmann et al., 1999).