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BioMed Research International
Volume 2013 (2013), Article ID 918136, 13 pages
http://dx.doi.org/10.1155/2013/918136
Research Article

Transcriptional Profiling of Canker-Resistant Transgenic Sweet Orange (Citrus sinensis Osbeck) Constitutively Overexpressing a Spermidine Synthase Gene

1Key Laboratory of Horticultural Plant Biology (MOE), National Key Laboratory of Crop Genetic Improvement, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China
2Citrus Research Institute, Chinese Academy of Agricultural Sciences, Southwest University, Chongqing 400712, China

Received 29 July 2012; Revised 23 September 2012; Accepted 15 October 2012

Academic Editor: Juan Francisco Jiménez Bremont

Copyright © 2013 Xing-Zheng Fu and Ji-Hong Liu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Citrus canker disease caused by Xanthomonas citri subsp. citri (Xcc) is one of the most devastating diseases affecting the citrus industry worldwide. In our previous study, the canker-resistant transgenic sweet orange (Citrus sinensis Osbeck) plants were produced via constitutively overexpressing a spermidine synthase. To unravel the molecular mechanisms underlying Xcc resistance of the transgenic plants, in the present study global transcriptional profiling was compared between untransformed line (WT) and the transgenic line (TG9) by hybridizing with Affymetrix Citrus GeneChip. In total, 666 differentially expressed genes (DEGs) were identified, 448 upregulated, and 218 downregulated. The DEGs were classified into 33 categories after Gene ontology (GO) annotation, in which 68 genes are in response to stimulus and involved in immune system process, 12 genes are related to cell wall, and 13 genes belong to transcription factors. These genes and those related to starch and sucrose metabolism, glutathione metabolism, biosynthesis of phenylpropanoids, and plant hormones were hypothesized to play major roles in the canker resistance of TG9. Semiquantitative RT-PCR analysis showed that the transcript levels of several candidate genes in TG9 were significantly higher than in WT both before and after Xcc inoculation, indicating their potential association with canker disease.