Identification of differentially expressed genes in a spontaneous altered leaf shape mutant of the navel orange [Citrus sinensis (L.) Osbeck].

Most of the economically important citrus cultivars have originated from bud mutations. Leaf shape and structure are important factors that impact plant photosynthesis. We found a spontaneous bud mutant exhibiting a narrow leaf phenotype in navel orange [Citrus sinensis (L.) Osbeck]. To identify and characterize the genes involved in the formation of this trait, we performed suppression subtractive hybridization (SSH) and macroarray analysis. A total of 221 non-redundant differentially expressed transcripts were obtained. These transcripts included cell wall- and microtubule-related genes and two transcription factor-encoding genes, yabby and wox, which are crucial for leaf morphogenesis. Many highly redundant transcripts were associated with stress responses, while others, encoding caffeic acid 3-O-methyltransferase (EC 2.1.1.68) and a myb-like transcription factor, might be involved in the lignin pathway, which produces a component of secondary walls. Furthermore, real-time quantitative RT-PCR was performed for selected genes to validate the quality of the expressed sequence tags (ESTs) from the SSH libraries. This study represents an attempt to investigate the molecular mechanism associated with a leaf shape mutation, and its results provide new clues for understanding leaf shape mutations in citrus.

Transcriptome changes during fruit development and ripening of sweet orange (Citrus sinensis).

BACKGROUND: The transcriptome of the fruit pulp of the sweet orange variety Anliu (WT) and that of its red fleshed mutant Hong Anliu (MT) were compared to understand the dynamics and differential expression of genes expressed during fruit development and ripening. RESULTS: The transcriptomes of WT and MT were sampled at four developmental stages using an Illumina sequencing platform. A total of 19,440 and 18,829 genes were detected in MT and WT, respectively. Hierarchical clustering analysis revealed 24 expression patterns for the set of all genes detected, of which 20 were in common between MT and WT. Over 89% of the genes showed differential expression during fruit development and ripening in the WT. Functional categorization of the differentially expressed genes revealed that cell wall biosynthesis, carbohydrate and citric acid metabolism, carotenoid metabolism, and the response to stress were the most differentially regulated processes occurring during fruit development and ripening. CONCLUSION: A description of the transcriptomic changes occurring during fruit development and ripening was obtained in sweet orange, along with a dynamic view of the gene expression differences between the wild type and a red fleshed mutant.