Project name: Citrus reticulata

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.Overall design: 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.

Data type: Transcriptome or Gene expression

Sample scope: Multiisolate

Relevance: Agricultural

Release date: 2010-05-08

Last updated: 2009-04-29