Functional Analysis Of TFIIIA-Type Zinc Finger Protein Gene ZFP179 In Resistance To Rice Bacterial Blight Disease

Rice (Oryza sativa L.) is one of the most important monocotyledonous crops in the world.The outbreaks of diseases caused by bacteria, viruses, fungi and invertebrates always decrease both rice yield and quality. The rice disease has become increasingly serious in recent years due to deterioration of ecological environment and changes in production methods. At present, the research of rice diseases and pest resistance and the breeding of new varieties of cultivation, have become one of the important topics that need to be solved by the rice scientists all over the world. Rice are mainly infected by three major diseases:rice blast, bacterial leaf blight and sheath blight, and bacterial leaf blight is the most serious bacterial diseases in rice and it has been found in rice cultivation all over the world. Disease resistance in plants is the result of a series of defense responses, and the transcriptional regulation is the main form of plant defense response genes expression and regulation which may determine plant to exhibit disease resistance or susceptibility to pathogen infection, as well as anti-sensedegree. The role of transcription factors involves the transcriptional regulation of plant defense responses. Many types of plant transcription factors are related to disease resistance:the TGA family of bZIP type, the ERF transcription factor, the WRKY family of zinc finger protein, homeodomain protein, HSF protein, and MYB factor. Previously, a TFIIIA-type zinc finger protein gene related to abiotic stress, ZFP179, was cloned and characterized in our laboratory. In this study, based on the previous research, we further studied the function of ZFP179 in rice bacterial blight resistance. The main results are described below:1. To evaluate bacterial blight disease resistance, the T2, T3, T4 generation of transgenic rice plants with 35S:ZFP179,35S:ZFP182,35S:ZFP245, and 35S:ZFP252 were inoculated with Xoo strains PXO61 and Zhel73 by the leaf clipping method at the booting (panicle development) stage in the field. Through field investigation, we found that most of the ZFP179-overexpressing transgenic rice lines significantly improved the rice bacterial blight resistance, and the resistance was relatively heritable.2. The real-time RT-PCR analysis showed that ZFP179 was not only induced in the seedlings by signal molecules SA, MeJA, ABA, H2O2 treatments in different extent, but also induced by bacterial blight. Our data showed that ZFP179 may regulate expression of defense related genes as a transcription factor, and therefore regulate the rice bacterial blight resistance.3. Comparative analysis of the content of H2O2, activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) between ZFP179 transgenic rice and non-transgenic WT rice at 0,6,24,48,72 h post-inoculation, the results showed that the content of H2O2 in ZFP179-overexpressing transgenic rice was accumulated within 24-48 h after inoculation with Xanthomonas oryzae pv.oryzae (Xoo), following which the activities of the three antioxidant enzymes significantly increased. However, the accumulation of H2O2 in the non-transgenic WT rice was obviously less than that in ZFP179-overexpressing transgenic rice, and the increasing of enzymes activities was slower than that in the ZFP179-overexpressing transgenic rice. Our results suggest that ZFP179 may induce the disease resistance through the modulation of reactive oxygen species(ROS) level and even maintain the adequate ROS level by increase the activities of ROS-scavenging enzymes.