| Poor soil largely limits plant yields.Phosphorus is one of the indispensable mineral elements in plant growth and development.The content of total phosphorus in soil is very high,but the content of available phosphorus that can be directly absorbed and utilized by plants is low,which limits the yield of 30.00～40.00% of cultivated land.Applying phosphate fertilizer is a common method to improve yield and quality in agricultural production,but excessive application of phosphorus based fertilizers can cause severe environmental pollution and high production costs.In addition,phosphate mineral resources are non-renewable resources with very limited reserves.Therefore,using wild plants to cultivate crop varieties with tolerance to phosphorus deficiency or high phosphorus utilization efficiency is an efficient approach to cope with this problem.Wild soybean is a closely related wild species of soybean,with rich excellent characters and variation types such as tolerance to poor soil,which can be used as parental material for improving new soybean varieties.In this study,common wild soybean and poor-soil-tolerant wild soybean were used as experimental materials.By integration the use of metabolomics and transcriptomics,differences in growth parameters,types and contents of metabolites for reusing phosphorus on the membrane and membrane system protecting and related gene expression between two ecotypes of wild soybean seedlings leaves under normal and low phosphorus stress were analyzed,to determine whether wild soybean could resist low phosphorus stress by reusing phosphorus on the membrane and protecting the membrane system.The main results are as follows:(1)Under low phosphorus stress,the plant height,above-ground fresh and dry weight,root fresh and dry weight of poor-soil-tolerant wild soybean seedlings were decreased by 0.34,0.99,0.79,0.23,and 1.09-fold,respectively.The degree of inhibition was significantly lower than that of common wild soybean seedlings.(2)Under low phosphorus stress,glycerol-3-phosphate,an indicator of phospholipid degradation degree,was decreased by 1.54 and 2.21-fold in common and poor-soil-tolerant wild soybean seedlings leaves,respectively;caffeic acid and phenylalanine related to membrane protection were increased 0.06 and 0.37-fold,2.06 and 3.36-fold in common and poor-soil-tolerant wild soybean seedlings leaves,respectively.Shikimic acid and ferulic acid were decreased 0.47 and 0.11-fold in common wild soybean seedlings leaves,respectively,while increased 0.23 and 0.04-fold in poor-soil-tolerant wild soybean seedlings leaves,respectively.(3)Under low phosphorus stress,the gene encoding SQD2(a crucial enzyme in thiolipid biosynthesis)was specifically up regulated 2.64-fold in poor-soil-tolerant wild soybean seedlings leaves;the gene encoding β-glucosidase and chalcone synthase with related to membrane protection were up-regulated 3.40,2.71,4.11,and 7.71,2.22,2.05-fold in poor-soil-tolerant wild soybean seedlings leaves,respectively,but down-regulated in common wild soybean seedlings leaves;the gene encoding glucosyltransferase UGT74B1 with related to membrane protection was specifically down regulated 3.47-fold in poor-soil-tolerant wild soybean seedlings leaves.The above trial results proved that,the poor-soil-tolerant wild soybean enhanced glycerolipid metabolism to decompose phospholipids and release phosphorus for reuse to improve resistance to low phosphorus stress.The plants synthesized thiolipids to replace phospholipids and maintain membrane structure integrity and inhibited glucosinolate biosynthesis to promote phenylpropanoid biosynthesis,leading to the production of phenolic acids and flavonoids that removed reactive oxygen species and protected membrane system stability.This study provide new ideas for the evaluation and innovative utilization of wild soybean germplasm resources,and also provide germplasm resources and scientific information for the breeding and industrial application of new soybean varieties with low phosphorus tolerance. |
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