Proteomics Research On Low Phosphorus Tolerance Germplasm Of Soybean

Phosphorus deficiency not only affect the growth and development of soybean,increase the shedding of flowers and pods,but also inhibit the formation of root nodules,reduce the efficiency of nitrogen fixation,and finally seriously affect the yield and quality of soybean.Understanding the molecular mechanism of phosphorus absorption and utilization of soybean is helpful to cultivate phosphorus efficient varieties.In order to explore the proteomic mechanism of soybean tolerance to low phosphorus stress and explore the proteins（genes）in response to low phosphorus stress,Dong soybean-2（L2304）and low phosphorus sensitive summer soybean germplasm Hei soybean（L2140）were used as experimental materials to set two phosphorus levels,P+（1000μM KH₂PO₄）and P-（5μM KH₂PO₄）,respectively.The root proteins of Dong soybean-2（L2304）and Hei soybean（L2140）under low phosphorus stress for 15 days were sequenced by non-standard quantitative proteomics technique,and bioinformatics analysis was carried out by Max-Quant software.Finally,the soybean roots at different time points were detected by fluorescence quantitative detection,and the APase activity and total phosphorus content were determined and analyzed.The conclusions of this study are as follows:1.Proteomic analysis was carried out on the roots of Dong soybean-2（L2304）and Hei soybean（L2140）under low phosphorus stress and normal phosphorus stress.The results showed that there were significant differences in protein expression in response to low phosphorus stress among different soybean genotypes.Under low phosphorus stress,low phosphorus tolerant summer soybean germplasm L2304produced 1489 down-regulated proteins and 310 up-regulated proteins,while low-phosphorus sensitive summer soybean germplasm L2140 produced 1433down-regulated proteins and 323 up-regulated proteins.2.Through the comparative analysis of GO enrichment of two summer soybean germplasms,it was concluded that the mechanism of soybean tolerance to low phosphorus was mainly concentrated in redox reaction,lipid synthesis,fatty acid metabolism,hydrogen peroxide metabolism and so on.Based on the comparative analysis of KEGG enrichment,it is concluded that the mechanisms of soybean tolerance to low phosphorus are mainly enrichment metabolism,secondary metabolism and synthesis,signal pathway and stress regulation.3.Five candidate proteins for low phosphorus tolerance were screened from L2304,a low phosphorus resistant germplasm,namely linoleate 9s-lipoxygenase（Glyma.15G026500）,malate dehydrogenase（Glyma.05G227400）,primary amine oxidase（Glyma.20G145100）,fructokinase（phosphorylation）（Glyma.20G213300）and Aldose 1-epi-isomerase（Glyma.13G064200）.4.Under low phosphorus stress,the roots of Dong soybean-2（L2304）and Hei soybean（L2140）at different time points were analyzed by fluorescence quantitative q PCR.The results showed that the expression of all differential genes in L2304 was the highest at 15 days,and most of the differential genes in L2140 were the highest at25 days.Under low phosphorus stress,the expression of these low phosphorus tolerant candidate genes in low phosphorus sensitive germplasm L2140 should be about 10 days later than that in low phosphorus tolerant germplasm L2304.5.Under low phosphorus stress,the APase activity and total phosphorus content of Dong soybean-2（L2304）and Hei soybean（L2140）roots at different time points were measured and analyzed.The results showed that the activity of APase fluctuated most during 10～20d.With the increase of time,the content of total phosphorus in soybean root decreased gradually,but increased suddenly on the 20th day.Based on the comprehensive analysis,we think that 10～20d should be a phosphorus sensitive period after low phosphorus treatment.