Study On Root Characteristics Of Transgenic Cry2A* Rice Under Different Nitrogen Fertilizer Conditions

Rice is one of the main food crops in the world.With the development of population and economy,the demand for rice is increasing.However,rice is susceptible to insect infestations,resulting in yield loss.Among them,Lepidoptera pests are one of the most harmful pests.For this reason,scientists have developed insect-resistant transgenic Bt rice.And many studies have found that transgenic Bt rice is different from the parental control,which in turn affects its yield and resistance performance.But many researches on transgenic Bt rice were mostly concentrated in the above ground of the rice,the root traits had less research.Therefore,in order to explore the root traits of transgenic Cry2A*rice lines,this study took a pot experiment,setting nitrogen treatment and no nitrogen treatment,and transgenic Cry2A*rice lines of different receptors and different transgenic Cry2A*rice lines of the same receptor were used as test materials to study the root characteristics and yield performance of transgenic Cry2A*rice lines.And main research results were showed as follows:?1?Some of the transgenic Cry2A*rice lines had differences in root morphology,root-shoot ratio,biomass/root length compared to non-transgenic parent control,and these parameters obviously related with yield.The root length,root surface area,root dry weight,root length/leaf area,and root-shoot ratio of some MH63 transgenic rice lines were significantly lower,but the biomass/root length was higher compared to the parental control.The root length and root surface area in MH86?Cry2A*?were not significant difference,the root dry weight was 13.9%?33.8%lowered,but the root length/leaf area and spike biomass/root length were higher than that in MH86.The root length,root surface area and root dry weight of KY?Cry2A*?-1 significantly raised compared to KY131 at the flowering stage,and lower or no significant difference at the mature stage.?2?The root vigor of some transgenic Cry2A*rice lines was different from the non-transgenic parental control,but the performance of different varieties was not consistent.There was no significant difference in the root active absorption area and root hormone content between MH63 and its transgenic Cry2A*rice lines,but there was a difference in bleeding sap intensity.MH63?Cry2A*?-5 had 35.7%?75.4%lower bleeding sap intensity than MH63.There was no significant difference in root vigor between MH86?Cry2A*?and MH86.The root active absorption area of KY?Cry2A*?-1 at flowering stage was significantly higher than that of the parent control without nitrogen treatment,and there was no significant difference under nitrogen treatment.?3?The yield of some transgenic Cry2A*rice lines was lower than the parental control,and the yield of some lines was not significantly different from the parental control or even higher than the parental control.The yields of KY131 and KY?Cry2A*?were not significantly different,but the seed setting rate of KY?Cry2A*?was significantly lower than that of the parental control without nitrogen treatment.The yield of some MH63 series transgenic Cry2A*rice lines was 21.4%?46.7%lower compared to the parental control,the main reason was that the effective panicle and seed setting rate were lowered than the parental control.The yield of other lines is not significantly different from the parental control.The yield of MH86?Cry2A*?was 13.9%lower in no nitrogen treatment,and 27.1%higher under nitrogen treatment than that of MH86.From the perspective of yield composition,there were differences in the number of spikes and seed setting rate.There were some differences in biomass accumulation and distribution,agronomic traits between the transgenic Cry2A*rice lines and their parental controls.?4?A few transgenic Cry2A*rice lines had differences in total nitrogen accumulation,root nitrogen accumulation compared to parental control.The Cry2A*protein content in roots of transgenic lines was significantly lower than that in leaves.The nitrogen accumulation of MH86?Cry2A*?and KY?Cry2A*?was not significantly different from that of their parental controls,but the nitrogen accumulation of some MH63 transgenic Cry2A*rice lines was 26.5%?37.2%higher compared to parental control,the main difference was in the root nitrogen accumulation.The root Cry2A*protein content was 0.28?g g^-1?2.76?g g^-1,and the Cry2A*protein content of the leaves was 2.54?g g^-1?17.09?g g^-1.The Cry2A*protein content in the roots and leaves of some lines showed an increasing trend in the late growth period,while the total protein content continued to decline,so the proportion of Cry2A*protein increased.Application of nitrogen fertilizer can increase the expression of Cry2A*protein.The results of this experiment showed that there were certain differences in root morphology,root physiology,yield performance and agronomic traits between transgenic Cry2A*rice lines and their parental controls,but the performance of different varieties was inconsistent.The performance of some lines was worse than the parental control,while the performance of some line was no difference or even better than that in the parental control.The difference in some traits can be eliminated by applying nitrogen fertilizer.Therefore,it is possible to reduce or eliminate the difference in traits between the transgenic rice and the parents control through further screening and optimization of the lines or the regulation of nitrogen fertilizer management to ensure the stable performance of the transgenic rice yield and resistance potential.