Screening Of Low Nitrogen Tolerance Varieties And Genome-Wide Association Analysis Of Low Nitrogen Tolerance-Related Traits In Foxtail Millet

Foxtail millet is drought-tolerant and barren-tolerant,and is one of the major cereal crops.In recent years the demand for foxtail millet continues to rise.Therefore,nitrogen fertilizer is widely used to improve foxtail millet production.However,nitrogen is not beneficial to the environment,nor is it conductive to the economic benefits.Therefore,screening nitrogen-efficient millet varieties,and fully digging out and using genes for millet nitrogen efficient absorption are of great significance for improving crop nitrogen fertilizer utilization efficiency,developing resource-saving and environment-friendly sustainable agriculture.In this experiment,a hydroponic method was used to screen 328 foxtail millet core germplasm resources for whole-genome resequencing and development of SNP and In Del molecular markers.Based on this,the plant height,root length,stem thickness,leaf width,fresh weight above ground,fresh weight below ground,dry weight above ground,dry weight below ground,and chlorophyll content under low nitrogen and normal nitrogen conditions were analyzed and used.Genome-wide association analysis preliminarily located genes related to the above nitrogen uptake and utilization traits.1.The pre-experiment set 5 different concentrations of nitrogen,0.2 m M,0.5 m M,1.0 m M,2.0 m M,and 5.0 m M KNO3..The phenotypes of 10 different foxtail millet varieties at the above concentrations were analyzed,and the results showed that 0.2 m M and 2.0 m M KNO3 could be used as low nitrogen and normal nitrogen treatment concentrations.2.Under the condition of low nitrogen stress,all foxtail millet varieties showed thin and short plants,increased root length,narrowed leaves and yellow leaves,and decreased weight of aboveground and underground parts at the seedling stage.Different varieties have different phenotypes under low nitrogen stress,which means that they have different ability to tolerate low nitrogen stress3.In the seedling stage,according to the coefficient of variation and correlation of the relative values of each index,six indexes were selected as reliable indexes for selecting low nitrogen tolerant varieties,including plant height,fresh weight on the ground,dry weight under the ground,dry weight above the ground,chlorophyll and fresh weight under the ground.4.Based on the result of principal component analysis and membership function analysis,ten varieties with low nitrogen tolerance were selected from 382 varieties: B57,B55,B163,B289,B311,B290,B6,JG21,B413 and B432.5.Through 10 × resequencing of 328 foxtail millet germplasm resources from different regions,1410570 high-quality SNP loci were obtained.These SNPs were used to analyze the population structure of328 materials.The results showed that the 328 materials were divided into 9 subgroups.6.Through the whole genome association an alysis of low nitrogen tolerance related traits,the above ground dry weight was located to 8 segments,the underground dry weight to 14 segments,the root length to 2 segments,the stem diameter to 13 segments,and the leaf width to 9 segments;Through the analysis of the whole gene association of chlorophyll content after low-nitrogen treatment for 2 days and 4 days,it was found that after 2 days of low-nitrogen treatment,2 sections were located,and after 4 days of low-nitrogen treatment,4 sections were located.