Functional Analysis Of Ricc ERF Transcription Factor B-3Subgroup Genes

ERF (ethylene-responsive factor) transcription factors is one of the largest subgroup of AP2/ERF transcription factor family, whose members have been shown to play important roles in biotic and abiotic stress response in plants. In previous study, we identified a rice ERF B-3subgroup geneOsBIERF3and found that overexpression of OsBIERF3in tobacco resulted in enhanced disease resistance against infection by tomato mosaic virus and the bacterial wild fire pathogen, Pseudomonas syringae pv. tabaci. Recent studies have also demonstrated that many ERF B-3subgroup genes have important functions in regulation of defense response against biotic and abiotic stress. The objectives of this study were to identify the ERF B-3subgroup genes from rice and explore their possible functionsin biotic and abiotic stress response using overexpression and RNA interference (RNAi) approaches.1. Identification of rice ERF B-3subgroup genes and expression profile analysisA total of15rice ERF B-3subgroup genes were obtained by RT-PCR. Most of the genes could be induced by treatment with hormone ACC and JA, but their expression patterns in response to JA or ACC differed in timing and levels. Transcriptional activity assays revealed that3representative ERF B-3members(OsBIERF3, Os08g44960and Os04g46220) showed transcriptional activation activity in yeast.2. Construction of over-expression and RNAi constructs and rice transformationTo explores the possible function of the rice ERF B-3subgroup genes, we constructed over-expression (OE) and RNAi vectors for each ERF B-3subgroup genes. Theseconstructs were then transformed into rice by method. A total of27OE lines and20RNAi lines for OsBIERF3,15OE lines and6RNAi lines for Os04g46220,6OE lines and2RNAi lines for Os05g49010, and10OE lines for Os02g45130were obtained. Most of the T1transgenic plants were true transgenic lines according to detection analysis of hygromycin resistance. The expression of the target genes were up regulated or down regulated in OE or RNAi lines as revealed by real-time PCR analysis.3. Functional analysis of OsBIERF3against abiotic stressThe OsBIERF3OE and RNAi T1plants were treated with cold, high salt and drought. The results showed that OsBIERF3RNAi lines showed enhanced resistance to cold, the death rate of RNAi lines were significantly lower than the OE lines. Height, root length and fresh weight of the OE seedlings werel higher than the RNAi plants under high salt condition. These results indicated that OsBIERF3positively regulate rice to high salt stress response but negatively regulate cold stress response. There is no significant difference in OsBIERF3OE and RNAi plants in response to droughtstress.