title: TRANSPARENT TESTA2 regulates embryonic fatty acid biosynthesis by targeting FUSCA3 during the early developmental stage of Arabidopsis seeds.
abstract: TRANSPARENT TESTA2 (TT2) regulates the biosynthesis of proanthocyanidins in the seed coat of Arabidopsis. We recently found that TT2 also participates in inhibition of fatty acid (FA) biosynthesis in the seed embryo. However, the mechanism by which TT2 suppresses the accumulation of seed FA remains unclear. In this study, we show that TT2 is expressed in embryos at an early developmental stage. TT2 is directly bound to the regulatory region of FUSCA3 (FUS3), and mediates the expression of numerous genes in the FA biosynthesis pathway. These genes include BCCP2, CAC2, MOD1 and KASII, which encode proteins involved in the initial steps of FA chain formation, FAD2 and FAD3, which are responsible for FA desaturation, and FAE1, which catalyzes very-long-chain FA elongation. Loss of function of TT2 results in reduced expression of GLABRA2 but does not cause a significant reduction in the mucilage attached to the seed coats, which competes with FA for photosynthates. TT2 is expressed in both maternal seed coats and embryonic tissues, but proanthocyanidins are only found in wild-type seed coats and not in embryonic tissues. The amount of proanthocyanidins in the seed coat is negatively correlated with the amount of FAs in the embryo.
authors.affiliation: Provincial Key Laboratory of Crop Gene Resources, College of Agriculture and Biotechnology, Zhejiang University, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Wang
authors.forename: Mingxun
authors.initials: M
authors.lastname: Chen
authors.forename: Tianlong
authors.initials: T
authors.lastname: Chen
authors.forename: Lijie
authors.initials: L
authors.lastname: Xuan
authors.forename: Zhilan
authors.initials: Z
authors.lastname: Li
authors.forename: Xue
authors.initials: X
authors.lastname: Du
authors.forename: Longhua
authors.initials: L
authors.lastname: Zhou
authors.forename: Guoping
authors.initials: G
authors.lastname: Zhang
authors.forename: Lixi
authors.initials: L
authors.lastname: Jiang
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D000081031:Fatty Acid Elongases; D005227:Fatty Acids / Q000096:biosynthesis*; D018398:Homeodomain Proteins / Q000378:metabolism; D012639:Seeds / Q000254:growth & development* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C502726:FUSCA3 protein, Arabidopsis; D005227:Fatty Acids; C089991:GL2 protein, Arabidopsis; D018398:Homeodomain Proteins; C451324:TT2 protein, Arabidopsis; D014157:Transcription Factors; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases
keywords: Arabidopsis; FUSCA3; TRANSPARENT TESTA2; embryonic development; fatty acid biosynthesis; yellow seed coat