Lipidomics Reveals Dynamic Changes of Starch Granule-Associated Lipids during Rice Grain Filling

This study explored dynamic changes in starch granule-associated lipids (SGALs) during rice grain filling, including granule surface lipids (GSLs) and internal lipids (GILs). SGAL content increased from 0.335% at 6 days after anthesis (DAA) to 0.684% at DAA 46. Lipidomics identified 423 lipids in GSLs and 148 lipids in GILs, with triglycerides being the most abundant. In GSLs, 23 lipids, including phosphatidic acid (5:0_16:0), monoacylglycerol (18:1), and lysophosphatidylglycerol (14:0), were upregulated from DAA 6 to 22. The GSLs showing changes during grain filling may be related to amyloplast membrane metabolism. For GILs, 7 lipids were upregulated from DAA 6 to 22, with only acyl carnitine (25:8) upregulated between DAA 22 and 46. Triglycerides (11:0_8:0_10:0) and (P-10:0_16:2) increased first and then decreased, suggesting changes in intracellular lipid dynamics related to carbon partitioning. This study detailed changes in SGALs during rice grain filling, revealing their potential roles in starch biosynthesis.