The Research Of Characteristic Expression Of Transcription Factor Between Winter Wheat Varieties In Low Temperature And Measurement Of Some Physiological Traits

In the northeast of China, the winter is cold and long, the average temperature in winter is between- 20 ℃ and 30 ℃. Planting winter wheat in high-cold area, also called northward relocation of winter wheat, is one of the effective measures to improve the production efficiency of wheat in this circumstance. How to further enhance the hardiness of winter wheat varieties, ensure the safety wintering of cold winter wheat, is still an important research content in northward relocation of winter wheat. Now the researchers have studied the mechanism of cold tolerance about hardiness of winter wheat in many fields, such as cytology, morphology, biochemical and physiological indexes and molecular biology research and so on. They found that the hardiness of winter wheat was concerned with their physiological characteristics, genetic factors, and the interaction of external environment. In addition, with the rapidly development of molecular biology, the mechanism of the winter wheat hardiness is more and more clear, and acquired a lot of cold hardiness genes, but whether these cold hardiness genes is important element to improve winter wheat hardiness is still no definite conclusion. Therefore, this study focuses on the comparison of cold hardiness difference between different cold winter wheat varieties and the expression quantity of 10 WRKY transcription factors under cold acclimation and freezing conditions, for providing a theoretical basis for future breeding work.This study chose a winter wheat variety with strong cold hardiness Dongnongmai1 as the object of study, and the winter wheat with weak cold resistance Jimai 22 as control. After cultivating seedlings in the laboratory nursery, start the cold acclimation until the three-leaf period of the seedlings, then treated the winter wheat plants domesticated with different temperature gradient process and measured the protective enzyme activity reflecting the degree of damage at low temperature levels. Establish standards for each low temperature gradient for winter wheat domestication process in the laboratory, in order to achieve a low temperature of winter wheat varieties quickly and accurately identify.The test results showed that the change trend of POD activity of Dongnongdongmai1 and Jimai22 during the freezing process was rising at first then falling and rising again, while in the freezing treatment(-10 ℃ 2 h), the POD activity of Dongnongdongmai1 was stronger than Jimai22. During the cold acclimation,the PPO activity of Dongnongdongmai1 was always higher than the Jimai22, and after freezing(-10 ℃ 2 h and then-12 ℃ 2 h),the PPO activity of Dongnongdongmai1 reached the maximum number, after the cryogenic treatment(-10 ℃ 2 h and then-12 ℃ 2 h), the proline content of Dongnongdongmai1 reached the maximum number, up to 4.63 Ug / g Dw, after the cryogenic treatment(-10 ℃ 2 h), the proline content Jimai22 up to 3.51 Ug / g Dw, therefore, the proline content and polyphenol oxidase activity can be used as indicators of cold tolerance identification at a low temperature.This study select 10 transcription factor genes: WRKY45, WRKY4, WRKY1, WRKY5 and WRKY transcription factor 24, WRKY transcription factor 3, WRKY11, CBFIVb-D20, CBFIVb-D9, Myb-like DNA-binding domain, and observing the differences of their expression quantity between the two different cold resistance winter wheat varieties at low temperature. The results showed that, after cryogenic treatment(-10 ℃ 2 h,-10 ℃ 2 h and then-12 ℃ 2 h), the expression of WRKY1, WRKY4, WRKY5 and WRKY transcription factor 24, WRKY11, CBFIVb-D20, CBFIVb-D9 in Dongnongdongmai1 was significantly higher than in Jimai22; after cryogenic treatment(-14 ℃ 2 h,-14 ℃ 2 h and then-16 ℃ 2 h), the expression of Myb-like DNA-binding domain in Dongnongdongmai1 was significantly higher than in Jimai22, after cryogenic treatment(-16 ℃ 2 h and-16 ℃ 2 h and then-18 ℃ 2 h), the expression of WRKY transcription factor 3 in Dongnongdongmai1 was significantly higher than in Jimai22. In Low temperature cold acclimation(10 ℃ / 4 ℃ 30 d), the expression of WRKY45 in Dongnongdongmai1 was significantly higher than cold Jimai22. Analysis showed that WRKY4, WRKY5 and WRKY transcription factor 24, WRKY11, CBFIVb-D20, CBFIVb-D9 belong freezing stress response gene; within them, WRKY5 and WRKY transcription factor 24 expressed significantly differentially, played an important regulatory role in strong cold resistance of Dongnongdongmai1. The 10 transcription factors analyzed in this study all increased to the maximum at different times after treatment in Dongnongdongmai1 relative to Jimai22 in low temperature gradient. Because the cold hardiness of Dongnongdongma1 winter wheat cultivars were significantly higher than Jimai22 Winter Wheat [147]. It follows that low temperature can induce the expression of these transcription factors in the high parts of the tillering node, high expression of these transcription factors can pass some way to improve plant cold resistance. But these transcription factors will not last long and express a lot, they just will be induced to express excessively under specific processings and specific times.