title: SlNCED1 and SlCYP707A2: key genes involved in ABA metabolism during tomato fruit ripening.
abstract: Abscisic acid (ABA) plays an important role in fruit development and ripening. Here, three NCED genes encoding 9-cis-epoxycarotenoid dioxygenase (NCED, a key enzyme in the ABA biosynthetic pathway) and three CYP707A genes encoding ABA 8'-hydroxylase (a key enzyme in the oxidative catabolism of ABA) were identified in tomato fruit by tobacco rattle virus-induced gene silencing (VIGS). Quantitative real-time PCR showed that VIGS-treated tomato fruits had significant reductions in target gene transcripts. In SlNCED1-RNAi-treated fruits, ripening slowed down, and the entire fruit turned to orange instead of red as in the control. In comparison, the downregulation of SlCYP707A2 expression in SlCYP707A2-silenced fruit could promote ripening; for example, colouring was quicker than in the control. Silencing SlNCED2/3 or SlCYP707A1/3 made no significant difference to fruit ripening comparing RNAi-treated fruits with control fruits. ABA accumulation and SlNCED1transcript levels in the SlNCED1-RNAi-treated fruit were downregulated to 21% and 19% of those in control fruit, respectively, but upregulated in SlCYP707A2-RNAi-treated fruit. Silencing SlNCED1 or SlCYP707A2 by VIGS significantly altered the transcripts of a set of both ABA-responsive and ripening-related genes, including ABA-signalling genes (PYL1, PP2C1, and SnRK2.2), lycopene-synthesis genes (SlBcyc, SlPSY1 and SlPDS), and cell wall-degrading genes (SlPG1, SlEXP, and SlXET) during ripening. These data indicate that SlNCED1 and SlCYP707A2 are key genes in the regulation of ABA synthesis and catabolism, and are involved in fruit ripening as positive and negative regulators, respectively.
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Kai
authors.initials: K
authors.lastname: Ji
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Kai
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhao
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Chemistry and Biochemistry, University of Arizona, 1306 East University BouleVard, Tucson, USA.
authors.forename: Bing
authors.initials: B
authors.lastname: Yuan
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Shengjie
authors.initials: S
authors.lastname: Dai
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Pei
authors.initials: P
authors.lastname: Chen
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Pei
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Hongqing
authors.initials: H
authors.lastname: Wang
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Yangdong
authors.initials: Y
authors.lastname: Guo
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China pleng@cau.edu.cn.
authors.forename: Ping
authors.initials: P
authors.lastname: Leng
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D005638:Fruit / Q000254:growth & development* / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000254:growth & development* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference
chemical_list: D010940:Plant Proteins; D000040:Abscisic Acid
keywords: Abscisic acid (ABA); SlCYP707A2; SlNCED1; tobacco rattle virus; tomato fruit ripening; virus-induced gene silencing (VIGS).