RNA-sequencing for peel roughing disorder of Satsuma mandarin fruit.
Ontology highlight
ABSTRACT: Roughing disorder (RD) is a significant quality barrier in citrus fruit, occurring more easily on easy-peeling mandarins. As RD is not yet well understood, this study aimed to examine the changes and synergic molecular processes involved. Peel with RD was induced by severely defruiting Satsuma mandarin trees. Morphology observations, RNA-sequencing and untargeted and targeted metabolic analyses were conducted.
Project description:In mandarin (Citrus reticulata Blanco), rind separation is an essential trait for marketing, as it confers easy-peeling, an inheritable trait whose genetic basis has not yet been characterized. To this end, we used the 30 K Affymetrix Citrus GeneChip to compare gene expression in albedo tissues of an easy-peeling genotype (Clementine Nules) to a less easy-peeling hybrid genotype (Lee x Nova, USDA 88-2) at three time points: before, at and after the onset of rind separation. A high percent of genes were detected reliably by the chip (76.1 %), and Principal Component Analysis (PCA) based on these genes showed that three replicates were well clustered, indicating the reliability of the data set. Functional analysis of genes showing >5-fold difference in expression between Clementine Nules and Lee x Nova across three developmental points suggested that the transcriptome of the two varieties diverges as the maturation process advances. A pectin methylesterase was expressed at levels more than 100-fold higher in Clementine Nules than in Lee x Nova at all three time points and two genes encoding for pectinases were more than 10-fold higher in Clementine Nules than in Lee x Nova during the last sampling time. Different hydrolases, a glucanase and a carbohydrate kinase were higher in Nules than in Lee x Nova. Higher expression of two cellulose synthases, an expansin and an aquaporin was observed in the easy peel genotype Clementine Nules. The difference between Clementine Nules and Lee x Nova at the transcript level suggests that three main molecular mechanisms are involved in the easy peeling trait: 1) lower cell adhesion, 2) pronounced degradation of albedo cell wall polysaccharides, and 3) high and extended cell expansion rate of the rind. We used the 30 K Affymetrix Citrus GeneChip to compare gene expression in albedo tissues of an easy-peeling genotype (Clementine Nules) to a less easy-peeling hybrid genotype (Lee x Nova, USDA 88-2) at three time points (16 arrays): before, at and after the onset of rind separation.
Project description:In mandarin (Citrus reticulata Blanco), rind separation is an essential trait for marketing, as it confers easy-peeling, an inheritable trait whose genetic basis has not yet been characterized. To this end, we used the 30 K Affymetrix Citrus GeneChip to compare gene expression in albedo tissues of an easy-peeling genotype (Clementine Nules) to a less easy-peeling hybrid genotype (Lee x Nova, USDA 88-2) at three time points: before, at and after the onset of rind separation. A high percent of genes were detected reliably by the chip (76.1 %), and Principal Component Analysis (PCA) based on these genes showed that three replicates were well clustered, indicating the reliability of the data set. Functional analysis of genes showing >5-fold difference in expression between Clementine Nules and Lee x Nova across three developmental points suggested that the transcriptome of the two varieties diverges as the maturation process advances. A pectin methylesterase was expressed at levels more than 100-fold higher in Clementine Nules than in Lee x Nova at all three time points and two genes encoding for pectinases were more than 10-fold higher in Clementine Nules than in Lee x Nova during the last sampling time. Different hydrolases, a glucanase and a carbohydrate kinase were higher in Nules than in Lee x Nova. Higher expression of two cellulose synthases, an expansin and an aquaporin was observed in the easy peel genotype Clementine Nules. The difference between Clementine Nules and Lee x Nova at the transcript level suggests that three main molecular mechanisms are involved in the easy peeling trait: 1) lower cell adhesion, 2) pronounced degradation of albedo cell wall polysaccharides, and 3) high and extended cell expansion rate of the rind.
Project description:To identify genes associated with citrus peel development and manifestation of peel disorders, we analyzed flavedo, albedo and juice sac tissues from five types of citrus fruit including, mandarin orange, navel orange, valencia orange, grapefruit and lemon.
Project description:To identify genes associated with citrus peel development and manifestation of peel disorders, we analyzed flavedo, albedo and juice sac tissues from five types of citrus fruit including, mandarin orange, navel orange, valencia orange, grapefruit and lemon. Fruits of five different citrus cultivars. Mature, healthy fruits of five different citrus cultivars (M-bM-^@M-^\ValenciaM-bM-^@M-^] and M-bM-^@M-^\NavelM-bM-^@M-^] orange [Citrus sinensis], mandarin [Citrus reticulata], lemon [Citrus M-CM-^W limon], grapefruit [Citrus M-CM-^W paradisi]) were purchased from a food market located in Davis, CA, USA. For all five types of fruit, three tissues (flavedo, albedo, and juice sacs) were compared separately. Each of the three tissues from each of the five types of fruit were sampled in three biological replicates, for a total of 45 samples. Samples were prepared from a 1 cm-thick equatorial disc and four sections (N, S, E, and W) were cut. Each section of flavedo, albedo, and juice sac tissue was dissected. gene expression variation underlying quality trait, different genotypes
Project description:Epithelial cells (EC) lining the most inner layers of secretory glands in Citrus peel are hypothesized to be the specialized cells that synthesize citrus essential oil. The major biosynthetic pathway(s) for essential oil are therefore postulated to be specifically and highly active in EC; transcripts that are involved in the pathway(s) are expected to be highly up-regulated in the cells as well. We performed cell-specific transcriptional analysis using GeneChip Citrus Genome Arrays to probe the global gene expression in EC during initial stage of essential oil biosynthesis and to identify groups of highly expressed genes in the EC.
Project description:We performed whole genome re-sequencing to reveal the comprehensive genetic variation of the fruit development between kumquat (Fortunella japonica) and Clementine mandarin. Total 5,865,235 single-nucleotide polymorphisms (SNPs) and 414,447 insertion/deletion (InDels) were identified in the two citrus species. Meanwhile, a total of 640,801 SNPs and 20,733 InDels were identified based on integrative analysis of genome and transcriptome of fruit. The variation feature, genomic distribution, functional effect and other characteristics of these genetic variation were explored. Total 1,090 differentially expressed genes (DEGs) were found during fruit development process of kumquat and Clementine mandarin by RNA-sequencing. Gene Ontology revealed that these genes were involved in various molecular functional and biological processes. Meanwhile, the genetic variation of 939 DEGs and 74 multiple fruit development pathway genes from previous reported were also identified. In addition, a global survey of genes splicing events identified 24,237 specific alternative splicing (AS) events in the two citrus species and showed that intron retention is the most prevalent pattern of alternative splicing.
Project description:Epithelial cells (EC) lining the most inner layers of secretory glands in Citrus peel are hypothesized to be the specialized cells that synthesize citrus essential oil. The major biosynthetic pathway(s) for essential oil are therefore postulated to be specifically and highly active in EC; transcripts that are involved in the pathway(s) are expected to be highly up-regulated in the cells as well. We performed cell-specific transcriptional analysis using GeneChip Citrus Genome Arrays to probe the global gene expression in EC during initial stage of essential oil biosynthesis and to identify groups of highly expressed genes in the EC. Grapefruits of two different sizes (diameters at 28 mm and 41 mm), at which points where biosynthesis of essential oil entering its active phase, were selected for the purpose of this experiment. For comparison, we selected parenchyma cells (PC), the non-oil-biosynthesizing cells, as the control cell type. Grapefruit peels were fixed, embedded in paraffin, sectioned and mounted on slides prior to cells isolation using laser microdissection and pressure catapulting. RNA was extracted from the isolated cells and then used for microarray hybridization. Transcriptional analysis were carried out by comparing transcript profiles between different cell types of the same time points, and same cell type at the different time points.