The Cloning And Analysis Of Three Stress-related Transcription Factors From Caragana Intermedia

Under natural environment, plants suffer many adverse effects, such as drought, saline, extreme temperature, etc, which have a negative influence on the vegetable growth and development of plants. These stress conditions impact the crop yields. Plants undergo many tiers of adjustments at physiology, biochemistry and molecular level, in order to survive from the abiotic stresses. These adjustments result in heterogeneous distribution of plants, and are related to the growth characteristics and the internal regulation mechanism of plants.Caragana intermedia Kuang et H. C. Fu distributes in the arid and semi-arid area, it is drought, saline and extreme temperature tolerant, and was used widely in sand fixation, soil and water preservation with highecology value. Is is also the raw materials for paper making and an important forage grass for sheep and camel, especially during the severe cold winter time.NAC(NAM, ATAF and CUC) is one of the largest plant-specific transcription factor families, and MYB transcription factors exist in both animals and plants, but they belong to one of the largest transcription factor families in plants. Members in both families play a critical role in abiotic stress responses. In this study, two genes encoding NAC transcription factors and one gene encoding MYB transcription factor from C. intermedia were cloned, and their functions were identified, the detailed results are as following:1. Two stress related NAC transcription factors, CiNAC3 and CiNAC4, were isolated. The cDNA sequence of CiNAC3 was 1 644 bp which encodes 388 amino acids.The c DNA sequence of CiNAC4 was 1 605 bp which encodes 344 amino acids. Sequence analysis showed that CiNAC3 and CiNAC4 contain the classical NAC domain, and they share the highest identify with Gm NAC3 and GmNAC4 from Glycine max about 76% and 80%, and with ANAC072 from Arabidopsis thaliana about 61% and 59%.2. CiNAC3 and CiNAC4 were induced by ABA and drought, dehydration, cold, heat, saline, and wounding. Localization assays revealed that CiNAC3 and CiNAC4 localized in the nuclei, consistent with their roles as transcription factors. Histochemistry assay using ProCiNAC4:GUS transgenic Arabidopsis showed that the expression of the GUS reporter was observed in many tissues of the transgenic plants, especially in the root vascular system, and was enhanced by wounding.3. Overexpression of CiNAC3 and CiNAC4 reduced ABA sensitivity during seed germination, and enhanced salt tolerance of the transgenic Arabidopsis. CiNAC4 also promoted the lateral root formation.4. Ci MYB177, a MYB transcription factor contain a R1 MYB-repeat, were isolated. Sequence analysis showed that Ci MYB177 shared the highest identify with GmMYB177 from G. max, and RVE2 from A. thaliana.5. The expression of Ci MYB177 was induced by abiotic stresses, and changed diurnally. Localization assays revealed that Ci MYB177 localized in the nuclei. Many light, circadian and stress related cis-elements were predicted in the promoter of Ci MYB177.