title: Comparative transcriptome analyses between a spontaneous late-ripening sweet orange mutant and its wild type suggest the functions of ABA, sucrose and JA during citrus fruit ripening.
abstract: A spontaneous late-ripening mutant of 'Jincheng' (C. sinensis L. Osbeck) sweet orange exhibited a delay of fruit pigmentation and harvesting. In this work, we studied the processes of orange fruit ripening through the comparative analysis between the Jincheng mutant and its wild type. This study revealed that the fruit quality began to differ on 166th days after anthesis. At this stage, fruits were subjected to transcriptome analysis by RNA sequencing. 13,412 differentially expressed unigenes (DEGs) were found. Of these unigenes, 75.8% were down-regulated in the wild type, suggesting that the transcription level of wild type was lower than that of the mutant during this stage. These DEGs were mainly clustered into five pathways: metabolic pathways, plant-pathogen interaction, spliceosome, biosynthesis of plant hormones and biosynthesis of phenylpropanoids. Therefore, the expression profiles of the genes that are involved in abscisic acid, sucrose, and jasmonic acid metabolism and signal transduction pathways were analyzed during the six fruit ripening stages. The results revealed the regulation mechanism of sweet orange fruit ripening metabolism in the following four aspects: First, the more mature orange fruits were, the lower the transcription levels were. Second, the expression level of PME boosted with the maturity of the citrus fruit. Therefore, the expression level of PME might represent the degree of the orange fruit ripeness. Third, the interaction of PP2C, PYR/PYL, and SnRK2 was peculiar to the orange fruit ripening process. Fourth, abscisic acid, sucrose, and jasmonic acid all took part in orange fruit ripening process and might interact with each other. These findings provide an insight into the intricate process of sweet orange fruit ripening.
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Ya-Jian
authors.initials: YJ
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Xing-Jian
authors.initials: XJ
authors.lastname: Wang
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Ju-Xun
authors.initials: JX
authors.lastname: Wu
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China; Kunming Academy of Agricultural Sciences, Kunming, 650000, China.
authors.forename: Shan-Yan
authors.initials: SY
authors.lastname: Chen
authors.affiliation: Engineering Technology College, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Chai
authors.affiliation: Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China; National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Hua-Lin
authors.initials: HL
authors.lastname: Yi
mesh_terms: D000040:Abscisic Acid / Q000096:biosynthesis*; D001483:Base Sequence; D032084:Citrus sinensis / Q000235:genetics* / Q000254:growth & development*; D003517:Cyclopentanes / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D054883:Oxylipins / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000096:biosynthesis / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D000071636:Protein Phosphatase 2C; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics; D017423:Sequence Analysis, RNA; D013395:Sucrose / Q000378:metabolism*; D059467:Transcriptome / Q000235:genetics
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D010940:Plant Proteins; D013395:Sucrose; C011006:jasmonic acid; D000040:Abscisic Acid; D017346:Protein Serine-Threonine Kinases; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C