Mitochondrial fatty acid β‐oxidation is required for storage‐lipid catabolism in a marine diatom

• DOI: 10.1111/nph.16744
• Publication Date: 2020-06-14T20:00:45Z
• Authors: Denis Jallet; Denghui Xing; Alexander Hughes; Mark Moosburner; Mark P. Simmons; Andrew E. Allen; Graham Peers
• Keywords: Phaeodactylum tricornutum; Catabolism; Endosymbiosis

Summary Photoautotrophic growth in nature requires the accumulation of energy‐containing molecules via photosynthesis during daylight to fuel nighttime catabolism. Many diatoms store photosynthate as neutral lipid triacylglycerol (TAG). While pathways diatom fatty acid and TAG synthesis appear be well conserved with plants, catabolism downstream β‐oxidation have not been characterised diatoms. We identified a putative mitochondria‐targeted, bacterial‐type acyl‐CoA dehydrogenase (PtMACAD1) that is present Stramenopile Hacrobian eukaryotes, but found animals or fungi. Gene knockout, protein‐YFP tags physiological assays were used determine PtMACAD1's role Phaeodactylum tricornutum . PtMACAD1 located mitochondria. Absence led no consumption at night slower light : dark cycles compared wild‐type. Accumulation transcripts encoding peroxisomal‐based did change response day knockout. Mutants also hyperaccumulated after amelioration N limitation. conclude utilise mitochondrial β‐oxidation; this stark contrast observed plants green algae. infer pattern caused by retention catabolic from host plastid secondary endosymbiosis.