title: High-level expression of a novel chromoplast phosphate transporter ClPHT4;2 is required for flesh color development in watermelon.
abstract: Chromoplast development plays a crucial role in controlling carotenoid content in watermelon flesh. Modern cultivated watermelons with colorful flesh are believed to originate from pale-colored and no-sweet progenitors. But the molecular basis of flesh color formation and regulation is poorly understood. More chromoplasts and released carotenoid globules were observed in the red-fleshed fruit of the 97103 cultivar than in the pale-colored fruits of the PI296341-FR line. Transcriptome profiles of these two materials identified Cla017962, predicted as ClPHT4;2, was dramatically up-regulated during flesh color formation. High ClPHT4;2 expression levels were closely correlated with increased flesh carotenoid contents among 198 representative watermelon accessions. Down-regulation of ClPHT4;2 expression in transgenic watermelons reduced the fruit carotenoid accumulation. ClPHT4;2 as a function of chromoplast-localized phosophate transporter was tested by heterologous expression into a yeast phosphate-uptake-defective mutant, western blotting, subcellular localization, and immunogold electron microscopy analysis. Two transcription factors, ClbZIP1 and ClbZIP2, were identified, which responded to ABA and sugar signaling to regulate ClPHT4;2 transcription only in cultivated watermelon species. Our findings suggest that elevated ClPHT4;2 gene expression is necessary for carotenoid accumulation, and may help to characterize the co-development of flesh color and sweetness during watermelon development and domestication.
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Jie
authors: J
authors: Zhang
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Shaogui
authors: S
authors: Guo
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Yi
authors: Y
authors: Ren
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Haiying
authors: H
authors: Zhang
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Guoyi
authors: G
authors: Gong
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Ming
authors: M
authors: Zhou
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Guizhang
authors: G
authors: Wang
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Mei
authors: M
authors: Zong
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Hongju
authors: H
authors: He
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Fan
authors: F
authors: Liu
authors: National Engineering Research Center for Vegetables, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing, 100097, China.
authors: Yong
authors: Y
authors: Xu
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D002338:Carotenoids / Q000096:biosynthesis; D029773:Citrullus / Q000187:drug effects / Q000235:genetics* / Q000648:ultrastructure; D060146:Ecotype; D005638:Fruit / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D005816:Genetic Complementation Test; D005947:Glucose / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D009154:Mutation / Q000235:genetics; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010641:Phenotype; D028061:Phosphate Transport Proteins / Q000235:genetics* / Q000378:metabolism; D010858:Pigmentation / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D018087:Plastids / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D011728:Pyridones / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D013347:Subcellular Fractions / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D009943:Organophosphorus Compounds; D028061:Phosphate Transport Proteins; D010940:Plant Proteins; D011728:Pyridones; D012333:RNA, Messenger; D014157:Transcription Factors; D002338:Carotenoids; C013351:fluridone; D013395:Sucrose; D000040:Abscisic Acid; D005947:Glucose; C088137:aminoethoxyvinylglycine; D005998:Glycine; C005073:ethephon
keywords: 
  Citrullus lanatus
  ; chromoplast; flesh color; phosphate transporter; transcriptional regulation