title: Fruit-specific RNAi-mediated suppression of SlNCED1 increases both lycopene and β-carotene contents in tomato fruit.
abstract: Abscisic acid (ABA) plays important roles during tomato fruit ripening. To study the regulation of carotenoid biosynthesis by ABA, the SlNCED1 gene encoding 9-cis-epoxycarotenoid dioxygenase (NCED), a key enzyme in the ABA biosynthesis, was suppressed in tomato plants by transformation with an RNA interference (RNAi) construct driven by a fruit-specific E8 promoter. ABA accumulation and SlNCED1 transcript levels in the transgenic fruit were down-regulated to between 20-50% of that in control fruit. This significant reduction in NCED activity led to the carbon that normally channels to free ABA as well as the ABA metabolite accumulation during ripening to be partially blocked. Therefore, this 'backlogged' carbon transformed into the carotenoid pathway in the RNAi lines resulted in increased assimilation and accumulation of upstream compounds in the pathway, chiefly lycopene and β-carotene. Fruit of all RNAi lines displayed deep red coloration compared with the pink colour of control fruit. The decrease in endogenous ABA in these transgenics resulted in an increase in ethylene, by increasing the transcription of genes related to the synthesis of ethylene during ripening. In conclusion, ABA potentially regulated the degree of pigmentation and carotenoid composition during ripening and could control, at least in part, ethylene production and action in climacteric tomato fruit.
authors.affiliation: College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, PR China.
authors.forename: Liang
authors.initials: L
authors.lastname: Sun
authors.forename: Bing
authors.initials: B
authors.lastname: Yuan
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Cui
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Leng
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology; D002338:Carotenoids / Q000378:metabolism*; D049308:Dioxygenases / Q000235:genetics* / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D005638:Fruit / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D000077276:Lycopene; D018551:Solanum lycopersicum / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D034622:RNA Interference / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013489:Suppression, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D019207:beta Carotene / Q000378:metabolism*
chemical_list: D005030:Ethylenes; D010940:Plant Proteins; D019207:beta Carotene; D002338:Carotenoids; D000040:Abscisic Acid; C036216:ethylene; D049308:Dioxygenases; C431939:carotenoid cleavage dioxygenase 1; D000077276:Lycopene