Ectopic expression of Hrf1 enhances bacterial resistance via regulation of diterpene phytoalexins, silicon and reactive oxygen species burst in rice

• Published in: PloS one 2012-09, Vol.7 (9), p.e43914
• Main Authors: Li, Wenqi, Shao, Min, Zhong, Weigong, Yang, Jie, Okada, Kazunori, Yamane, Hisakazu, Zhang, Lei, Wang, Guang, Wang, Dong, Xiao, Shanshan, Chang, Shanshan, Qian, Guoliang, Liu, Fengquan
• Format: Article
• Language: English
• Subjects: ABC transporters; Agriculture; Arabidopsis; Arabidopsis thaliana; Bacteria; Bacterial diseases; Bacterial infections; Bacterial Proteins - metabolism; Biology; Biosynthesis; Blight; Botrytis cinerea; Crop diseases; Deposition; Disease resistance; Disease Resistance - drug effects; Disease Resistance - genetics; Disease Resistance - immunology; Diterpenes - metabolism; Diterpenes - pharmacology; Drug resistance; Ectopic expression; Education; Electron microscopy; Erwinia amylovora; Gene expression; Gene Expression Regulation, Plant - drug effects; Genes; Gram-negative bacteria; Growth rate; Hydrogen; Hydrogen peroxide; Laboratories; Leaves; Localization; Magnaporthe grisea; Oryza; Oryza - genetics; Oryza - immunology; Oryza - microbiology; Oryza - ultrastructure; Oryza sativa; Oxygen; Pathogens; Physiological aspects; Phytoalexins; Plant diseases; Plant Diseases - genetics; Plant Diseases - immunology; Plant Diseases - microbiology; Plant Leaves - drug effects; Plant Leaves - genetics; Plant Leaves - microbiology; Plant Leaves - ultrastructure; Plants, Genetically Modified; Proteins; Reactive oxygen species; Reactive Oxygen Species - metabolism; Respiratory Burst - drug effects; Respiratory Burst - genetics; Rice; RNA, Messenger - genetics; RNA, Messenger - metabolism; Scanning electron microscopy; Sesquiterpenes - metabolism; Sesquiterpenes - pharmacology; Signal transduction; Silicon; Silicon - metabolism; Tobacco; Transcription activation; Transformation, Genetic - drug effects; X ray spectrometers; Xanthomonas - growth & development; Xanthomonas - metabolism; Xanthomonas oryzae
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0043914

Harpin proteins as elicitor derived from plant gram negative bacteria such as Xanthomonas oryzae pv. oryzae (Xoo), Erwinia amylovora induce disease resistance in plants by activating multiple defense responses. However, it is unclear whether phytoalexin production and ROS burst are involved in the disease resistance conferred by the expression of the harpin(Xoo) protein in rice. In this article, ectopic expression of hrf1 in rice enhanced resistance to bacterial blight. Accompanying with the activation of genes related to the phytoalexin biosynthesis pathway in hrf1-transformed rice, phytoalexins quickly and consistently accumulated concurrent with the limitation of bacterial growth rate. Moreover, the hrf1-transformed rice showed an increased ability for ROS scavenging and decreased hydrogen peroxide (H(2)O(2)) concentration. Furthermore, the localization and relative quantification of silicon deposition in rice leaves was detected by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS). Finally, the transcript levels of defense response genes increased in transformed rice. These results show a correlation between Xoo resistance and phytoalexin production, H(2)O(2), silicon deposition and defense gene expression in hrf1-transformed rice. These data are significant because they provide evidence for a better understanding the role of defense responses in the incompatible interaction between bacterial disease and hrf1-transformed plants. These data also supply an opportunity for generating nonspecific resistance to pathogens.