title: Senescence-inducible LEC2 enhances triacylglycerol accumulation in leaves without negatively affecting plant growth.
abstract: The synthesis of fatty acids and glycerolipids in wild-type Arabidopsis leaves does not typically lead to strong triacylglycerol (TAG) accumulation. LEAFY COTYLEDON2 (LEC2) is a master regulator of seed maturation and oil accumulation in seeds. Constitutive ectopic LEC2 expression causes somatic embryogenesis and defects in seedling growth. Here, we report that senescence-inducible LEC2 expression caused a threefold increase in TAG levels in transgenic leaves compared with that in the leaves of wild-type plants. Plant growth was not severely affected by the accumulation the TAG in response to LEC2 expression. The levels of plastid-synthesized lipids, mono- and di-galactosyldiacylglycerol and phosphatidylglycerol were reduced more in senescence-induced LEC2 than in endoplasmic reticulum-synthesized lipids, including phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol. Senescence-induced LEC2 up-regulated the expression of many genes involved in fatty acid and TAG biosynthesis at precise times in senescent leaves, including WRINKLED1 (WRI1), which encodes a fatty acid transcription factor. The expressions of glycerol-3-phosphate dehydrogenase 1 and phospholipid:diacylglycerol 2 were increased in the transgenic leaves. Five seed-type oleosin-encoding genes, expressed during oil-body formation, and the seed-specific FAE1 gene, which encodes the enzyme responsible for the synthesis of C20:1 and C22:1 fatty acids, were also expressed at higher levels in senescing transgenic leaves than in wild-type leaves. Senescence-inducible LEC2 triggers the key metabolic steps that increase TAG accumulation in vegetative tissues.
authors: Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Jeonju, Korea.
authors: Hyun Uk
authors: HU
authors: Kim
authors: Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Jeonju, Korea.
authors: Kyeong-Ryeol
authors: KR
authors: Lee
authors: Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Jeonju, Korea.
authors: Su-Jin
authors: SJ
authors: Jung
authors: Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Jeonju, Korea.
authors: Hyun A
authors: HA
authors: Shin
authors: Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, Korea.
authors: Young Sam
authors: YS
authors: Go
authors: Department of Bioenergy Science and Technology, Chonnam National University, Gwangju, Korea.
authors: Mi-Chung
authors: MC
authors: Suh
authors: Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Jeonju, Korea.
authors: Jong Bum
authors: JB
authors: Kim
mesh_terms: D000375:Aging / Q000502:physiology; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000502:physiology*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D008055:Lipids / Q000032:analysis / Q000502:physiology; D018515:Plant Leaves / Q000737:chemistry* / Q000502:physiology; D012639:Seeds / Q000254:growth & development; D014157:Transcription Factors / Q000502:physiology*; D014280:Triglycerides / Q000032:analysis* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C504240:LEC2 protein, Arabidopsis; D008055:Lipids; D014157:Transcription Factors; D014280:Triglycerides
keywords: LEC2; fatty acid; leaf senescence; seed maturation; transcription factor; triacylglycerol