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:Compared to what is known in model species, reproductive biology in citrus is still poorly understood. Although in recent years several efforts have been made to study pollen-pistil interaction and self-incompatibility, little information is available about the molecular mechanisms regulating these processes. We performed microarray analysis for the identification of candidate genes involved in pollen-pistil interaction and self-incompatibility in clementine (Citrus clementina Hort. ex Tan.). The analysis was performed comparing the transcriptome of laser-microdissected stylar canal cells isolated from two clementine genotypes differing for self-incompatibility response (‘Comune’, self-incompatible; and ‘Monreal’, a self compatible mutation of ‘Comune’).
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:The postharvest senescence processes of citrus fruits were analyzed transcriptomic. The present study was aimed to: further uncover the rind-flesh communication of hesperidium; characterize the differential storage behaviors of different citrus varieties; reveal the important changes during storing process; and demonstrate the specific non-climacteric characteristics of citrus fruits. We chose four major table fruit varieties of citrus: satsuma mandarin (Citrus unshiu Marc) (M), ponkan (Citrus reticulata Blanco) (K), newhall navel orange (Citrus sinensis L. Osbeck) (O) and shatian pummelo (Citrus grandis Osbeck) (P). They were sampled every 10 days during 50 DAH (days after harvest), almost covering the commercial storage period of loose-skin citrus.
Project description:The postharvest senescence processes of citrus fruits were analyzed transcriptomic. The present study was aimed to: further uncover the rind-flesh communication of hesperidium; characterize the differential storage behaviors of different citrus varieties; reveal the important changes during storing process; and demonstrate the specific non-climacteric characteristics of citrus fruits.
Project description:Somatic embryogenesis in nucellar tissues is widely recognized to induce polyembryony in major citrus varieties such as sweet oranges, satsuma mandarins and lemons. This capability for apomixis is attractive in agricultural production systems using hybrid seeds, and many studies have been performed to elucidate the molecular mechanisms of various types of apomixis. To identify the gene responsible for somatic embryogenesis in citrus, a custom oligo-DNA microarray including predicted genes in the citrus polyembryonic locus was used to compare the expression profiles in reproductive tissues between monoembryonic and polyembryonic varieties. The full length of CitRKD1, which was identified as a candidate gene responsible for citrus somatic embryogenesis, was isolated from satsuma mandarin and its molecular function was investigated using transgenic ‘Hamlin’ sweet orange by antisense-overexpression. The candidate gene CitRKD1, predominantly transcribed in reproductive tissues of polyembryonic varieties, is a member of the plant RWP-RK domain proteins. CitRKD1 of satsuma mandarin comprised two alleles (CitRKD1-mg1 and CitRKD1-mg2) at the polyembryonic locus controlling embryony type (mono/polyembryony) that were structurally divided into two types with or without a miniature inverted-repeat transposable element (MITE)-like insertion in the upstream region. CitRKD1-mg2 with the MITE insertion was the predominant transcript in flowers and young fruits where somatic embryogenesis of nucellar cells occurred. Loss of CitRKD1 function by antisense-overexpression abolished somatic embryogenesis in transgenic sweet orange and the transgenic T1 plants were confirmed to derive from zygotic embryos produced by self-pollination by DNA diagnosis. Genotyping PCR analysis of 95 citrus traditional and breeding varieties revealed that the CitRKD1 allele with the MITE insertion (polyembryonic allele) was dominant and major citrus varieties with the polyembryonic allele produced polyembryonic seeds.
Project description:Compared to what is known in model species, reproductive biology in citrus is still poorly understood. Although in recent years several efforts have been made to study pollen-pistil interaction and self-incompatibility, little information is available about the molecular mechanisms regulating these processes. We performed microarray analysis for the identification of candidate genes involved in pollen-pistil interaction and self-incompatibility in clementine (Citrus clementina Hort. ex Tan.). The analysis was performed comparing the transcriptome of laser-microdissected stylar canal cells isolated from two clementine genotypes differing for self-incompatibility response (‘Comune’, self-incompatible; and ‘Monreal’, a self compatible mutation of ‘Comune’). Styles with stigmas, collected 24 hours after self pollination, were immediately snap-frozen in OCT embedding medium (Sakura Finetek, Zoeterwoude, Netherlands) in Peel-A-Way plastic embedding molds (Polysciences, Polysciences, Warrington, PA, USA). Transversal sections 10 µm thick at the upper part of the style were cut with a Leica CM1900 cryostat (Leica Microsystems, Germany) at -20°C. A Leica AS Laser Microdissection system (Leica Microsystems) was used for the isolation of stylar canals from transversal sections. Canals from the stigma were discarded to avoid contamination with pollen or pollen tubes. Three biological replicates were prepared for each genotype. Each biological replicate consisted of bulks of about 200 microdissected areas (composed of an average of 50 cells) coming from two different molds
Project description:An experiment was performed to predict citrus varieties by means of supervised learning algorithms applied to gene expression profiles