| Soybean(Glycine max(L.)Merr.)is an important food and oil crop,which provides about 2/3 and 1/3 dietary protein and oil all of the world,respectively.However,the soybean yield per unit area is very low.Phosphate deficient is the one of the most important factors influencing the yield of soybean.It is an effective way to improve the resistant ability of low phosphorus stress though breeding soybean varieties with high phosphorus efficiency.There are rich alleles in soybean germplasm resources in China and identification of favorable alleles of phosphorus efficiency can be used for improving the phosphorus efficiency and thus promote soybean production.In addition,study on genes related soybean phosphorus efficiency has important practical significance for revealing the mechanism and germplasm improvement.In order to explore the genetic mechanism of phosphorus efficiency of soybean,a natural population consisted of 191 soybean materials were used to association analysis for phosphorus efficiency in two years experiment.Furthermore,we identified GmG3PTl gene according to Arabidopsis thaliana,which was a candidate gene related to phosphorus efficiency though the homology-based cloning method.The main results of this study were as following:Phenotype data for relative-plant height(RPH),relative-shoots dry weight(RSDW),relative-total phosphorus concentration(RPC),relative-phosphate uptake efficiency(RPAE)and relative-phosphate utilization efficiency(RPUE)of the soybean seedling from two field trials was used for SNPs detection by Tassel 4.0 software as well as the mean values of the crop seasons.A total of 93 SNPs were identified,including 39 SNPs for RPH,17 for RSDW,24 for RPAE and 13 for RPUE.Of the 93,18 SNPs were co-associated with two or more traits.And the T-test results shown that the favorable allelic effects of 12 out of the consistent 16 SNPs in two years were significantly higher than that the unfavorable allelic effects.Analysis by synthesis of SNPs,we found many SNPs were clustered on the location of chromosome 3,and this indicated SNPs hotspots existed on this chromosome controlling phosphorus efficiency related traits.In order to investigate the genetic basis of phosphorus efficiency of mature stage of soybean,GWAS was conducted to detect SNPs that associated with yield and yield-relatede traits with 1142 SNPs in 192 soybean accessions grown in different phosphate environment.Our results indicated that there was extensive phenotypic variation in 191 soybean accessions for yield and yield-relatede traits.119 SNPs-trait associations were detected with the models(Q+K),including 23 SNPs for RMPH,34 for RPiN,9 for RBN,16 for RPN;20 for RSDW;17 for RSY,and 10 SNPs co-associated with two or more traits.And the T-test results shown that the favorable allelic effects of 11 out of the consistent 17 SNPs in two years were significantly higher than that the unfavorable allelic effects.The real-time PCR results showed that GmG3PTl was highly expressed in root,and trace expression was detected in stem and leaf.When soybean seedlings were suffered from Pi deficiency for 7 days,GmG3PT1 was highly induced in shoots and root tissue,especially in root tissue.The expression patterns suggested that GmG3PT1 might involve in Pi remobilization.In order to further study the function of GmG3PT1,plant expression vector of 35S:GmG3PTl-pBI-121 was constructed and transformed into Arabidopsis thaliana.The positive T2 transgenic plants were used to analysis the ability to grow in phosphate-limited nutrient solution for 15 days.Compared with wild type(WT)plants,the number of lateral roots of the transgenic lines was significantly increased and also the available Pi concentration,but not for the total phosphorus concentration.This result indicated GmG3PT1 involved in reversing organic phosphorus to Pi,and played roles in maintaining Pi homeostasis under Pi-limited conditions.The expression level of GmG3PT1 was measured in natural population lines which were grown in the plus and minus phosphorus nutrient solution by real-time PCR.Correlation analysis between the expression level of GmG3PT1 and the shoot dry weight and available Pi concentration in root was performed.There was a significantly positive correlation between the expression level of GmG3PT1 and shoot dry weight of soybean planted in two nutrient solutions.Fifteen eQTLs of GmG3PT1 were detected,and BARC-041917-08135 was identified in both phosphorus nutrient solutions.It was interesting that BARC-041917-08135 was mapped at a distance of 5.4 cM from the GmG3PT1 gene.This suggested that BARC-041917-08135 was a cis-acting eQTL for the GmG3PT1 The rest markers associated with the expression of GmG3PT1 were far from GmG3PT1 gene,which suggested the expression of GmG3PT1 is co-regulated by cis-acting and trans-acting eQTLs.In addition,BARC-016657-02160 which was associated with the relative shoots dry weight was closed to BARC-041917-08135.This result suggested that GmG3PT1 may play a role for increasing shoot dry weight of soybean grown in phosphorus stress enviroment. |
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