Expression Of Section-drying Genes In Ponkan Mandarin

Section-drying is the widespread occurrence of physiological disorders in citrus during storage. After fruit morbidity, fruit pulp moisture decreased, the flavor fades, fruit weight was significantly reduced, thereby seriously affecting the economic efficiency of the citrus industry. This experiment takes Ponkan citrus as material, constructs a subtractive hybridization cDNA library, and obtains the Ponkan citrus Section-drying genes by library screening, cloning and sequencing, functional analysis and real-time quantitative RT-PCR confirmation. These genes reflected the regulation of pulp to Section-drying, and can be used to prevent the disorder of Section-drying as candidate genes.A suppression subtractive hybridization library was constructed using cDNA synthesized from RNA extracted from normal pulp as driver and Section-drying pulp as tester. A total of300positive clones were selected for sequencing, and a total of260EST sequences were obtained. After comparison with GenBank using the online software of the BLAST,197ESTs, involving in52genes, were found to share considerable homology with known genes while the rest63ESTs had low or even no homology with known genes. These differentially expressed genes were related to numerical biological processes such as aging, stress-tolerance, chitin and cell wall macromolecule catabolic and proteolysis.The expressions of the β-tubulin, senescence-associated protein, cytochrome c, cysteine protease, phosphoenolpyruvate carboxykinase, trafficking protein, aspartic protease precursor, WRKY transcription factor21genes were studied by real-time quantitative PCR. The eight genes were significantly up-regulated in Section-drying pulp, while β-actin gene as internal control gene. And, the upward expresses8time of genes to have the β-tubulin protein and the senescence-associated protein; the upward expresses5time of genes to have the cytochrome c protein and phosphoenolpyruvate carboxykinase protein; the upward expresses2time of genes to have the cysteine protease and the trafficking protein; the gene expression quantity of aspartic protease precursor and WRKY transcription factor21has the extremely obvious up-regulated, increases350times and120times separately.