The Evaluation For Glyphsate-tolerance Rice Germplasm Resources And Studies On Its Resistance Mechanism

With the change of planting system and the continuous expansion of direct seeding area,field weed control is the main cost of rice cultivation process.There are a wide variety of herbicides on the market,while only several weeds can be killed at a time,and the application time is limited.It is difficult to meet the needs of the current rice light cultivation.Breeding new rice varieties with resistance to herbicides is an important way to reduce the weeding cost.In addition,the current research and development progress of efficient,safe and environmentally friendly new herbicide is slow.Glyphosate is one of the most widely used herbicides in the world because of its low toxicity,high efficiency,cheap price and environmental compatibility.Its mechanism of action is through blocking the normal nitrogen metabolism after internal absorption,which lead to biological death.Glyphosate can kill the upper part of the plant and the roots at the same time and has good effect.In recent years,due to the cost advantages of herbicide-resistant transgenic varieties in terms of scale and mechanization,the application of the herbicide-resistant transgenic cultivars has become more and more extensive,and the planting area has been expanding year by year.It has also promoted large-scale development and promotion of herbicide-resistant transgenic cultivars.Monsanto's research on glyphosate-resistant transgenic cultivars has matured and has successfully commercialized a large number of glyphosate-resistant transgenic crops.China's research in this field started relatively late,and there are restrictions on the promotion of transgenic food crops,which lead to no commercial production of glyphosate-resistant transgenic rice.Therefore,this research focuses on the development of glyphosate-resistant non-transgenic rice varieties with independent intellectual property rights,reduce the production cost,and reduce the harm caused by the use of chemical pesticides to the environment.In this study,84 rice plants were screened for glyphosate resistance and the tolerant physiological mechanism was determined.The tolerance mechanism was further established to provide experimental materials and theoretical basis for future cultivation of glyphosate-tolerant crops and rice breeding.The results showed that the tolerance of different rice materials to glyphosate was quite different,indicating that the rice material itself had a natural tolerance gene.The main results of this study are as follows:1.84 rice from the "irradiation + EMS" after mutagenesis and hybridization of rice materials were different concentrations of glyphosate resistance screening and found that the rice material in 1mg/ml glyphosate can survive,no obvious symptoms of phytotoxicity,injury level of 1 to 2;glyphosate concentration of 2mg/ml and 3mg/ml,these materials on the tolerance of glyphosate are quite different,which CA11 and CA21 survival rate is high,83.3%;glyphosate concentration of 4mg/ml and 5mg/ml,the vast majority of plants atrophy,the whole death,injury level 5.The results showed that there were significant differences in glyphosate tolerance between different rice materials,and the agronomic traits of plant height,ear length,1000-grain weight and seed setting rate were selected to select CA5,CA6,CA11,CA19 and CA21 and other 5 resistant materials.2.Respectively,through the initial screening of five new glyphosate-tolerant rice germplasm at different stages of spraying different concentrations of glyphosate,the results found at 4mg/ml glyphosate concentration,5 resistant materials have different degrees.The survival rate of CA21 was the highest,while the control variety P1003 was completely killed,and the optimum concentration of 4mg/ml for glyphosate was determined.3.The results showed that different concentrations of 0.01mg/ml,0.05mg/ml,0.1mg/ml,0.5mg/ml and lmg/ml were used to study the seed germination test of CA21 and the control variety P1003.At the same time,the germination rate of rice material was different.Compared with the control(spraying water treatment),the test materials were damaged to varying degrees,and the growth of buds and roots was inhibited.At the concentration of Omg/ml,O.Olmg/ml and 0.05mg/ml glyphosate,the germination rate of CA21 was high and was not affected.0.1 mg/ml concentration of glyphosate treatment,CA21 germination rate of 66.7%,P1003 germination rate of 0.It can be seen that the concentration of glyphosate at 0.1 mg/ml can distinguish the difference between the resistant material and the control material in the bud stage,and the best concentration for the bud stage.4.The physiological indexes were determined by using the glyphosate-tolerant CA21 and the control variety P1003 as the materials.The physiological indexes of the plants were analyzed at 1?7d after treatment with different concentrations of glyphosate 1 mg/ml,2mg/ml,3mg/ml and 4mg/ml The results showed that the shikimic acid,malondialdehyde and chlorophyll content of CA21 did not change significantly with the increase of glyphosate,and the activity of GSTs increased significantly.The content of shikimic acid and malondialdehyde in control varieties P1003 increased significantly,Content and GSTs activity significantly reduced.In this study,the glyphosate-tolerant rice genetic resources selected under natural conditions could provide candidate materials for the subsequent cultivation of glyphosate-tolerant rice.