Analysis Of Low Nitrogen Tolerance And Related Gene Expression In Transgenic Millet Families

Foxtail millet is a multi-function crop,which has the characteristics of short growth period,drought resistance,infertility tolerance and strong resistance to stress.Nitrogen is an essential nutrient substance.One of the breeding purposes of foxtail millet is increasing yield by improving nitrogen use efficiency.In this study,the low nitrogen tolerance of wild-type and transgenic millet lines was identified by using principal component analysis and comprehensive evaluation D value by setting different levels of nitrogen treatment at both seedling and adult stages.The expression pattern of 8 low-nitrogen-tolerant related genes selected in our laboratory was analyzed.The main findings are as follows:1.Under low nitrogen stress,twenty two different traits of millet at mature period showed various degrees decline,except root length and root-crown ratio at seedling stage.2.The coefficient of variation of the low nitrogen tolerance coefficient of the three traits of biomass(CV=35.35%),economic yield(CV=28.75%)and grass weight(CV=27.07%)at adult stage was larger;Under the condition of hydroponic culture at seedling stage,the coefficient of variation of the four traits of low nitrogen tolerance was larger,including underground dry weight(CV=59.29%),aboveground fresh weight(CV=59.17%),leaf area(CV=49.52%)and single plant dry weight(CV=49.31%).3.The low nitrogen tolerance coefficient of each trait was analyzed by principal component analysis,and the low nitrogen tolerance of the tested materials was evaluated by the comprehensive evaluation D value method based on membership function.Seven foxtail millet lines were clustered into three categories under field cultivation and hydroponics by Euclidean distance measurement.Among them,strains 5 to NRT3.1B gene showed strong low nitrogen resistance under field cultivation and seedling hydropony,while strains 2,3 and 4 of NRT3.1A gene and 7 to NRT3.1B gene showed weak low nitrogen resistance.4.Line 5 of NRT3.1B gene reduces the expression of nitrile hydrothase and gluamide synthase genes under low nitrogen conditions,and improves the expression of cyanide hydrase gene,carbonate anhydrase gene,ferrin-nitrite reductase gene,which is conducive to coordinating the relevant nitrogen cycle and carbon cycle,thus improving the low nitrogen resistance of millet.