| Phosphorus is one of the most important nutrient elements for maize growth and development.Low phosphorus content in soil will seriously affect maize yield.At the same time,phosphorus is an important component of plasma membrane lipids.The lack of phosphorus will reduce the content of phospholipids in membrane lipids and then trigger membrane lipid remodeling,changing the composition and function of plasma membrane.In the previous research,our research group revealed the lipid metabolism pathway and the expression patterns of different lipid-related genes in the leaves of maize(18: 3 plants)under low phosphorus stress.In this study,maize inbred line He 344 was used as the experimental material,and high-throughput transcriptome sequencing and lipid group detection techniques were used to analyze the lipid metabolism regulation and gene expression of maize under phosphorus stress(-P: 5 μM KH2PO4;+P: 1000 μM KH2PO4).Combined with the determination of related physiological indicators,we explored key genes related to lipid metabolism and physiological changes under low-phosphorus stress.Below are key research findings:1.In this study,transcriptome sequencing of maize leaves under phosphate starvation at 1 and 7 days using the BMK sequencing platform showed that the number of genes in the1d5 vs 1dk comparison group was the highest,indicating that a large number of phosphate-responsive genes were induced during low phosphorus stress at 1d.Studies on the functional annotation of genes differentially expressed in response to phosphorus in maize roots have shown that the "Translation,ribosomal structure and biogenesis" have the most number of differentially expressed genes in 1d5 vs 1dk comparison group.In addition,comparing and annotating the up-regulated and down-regulated genes in the expression level(Fold Change)of more than 1(|Log2FC| ≥ 1),in the two comparison groups with the transcription factor database,the number of differentially expressed genes in the MYB and b HLH transcription factor families was found most.2.Under the low phosphate stress,the contents of MDA,SOD activities and POD activities in the roots of maize seedlings increased with the increase of stress time.Transcriptome data indicated that SOD,POD-related genes were differental expressed under low phosphate stress.The root activity and the content of Soluble protein were decreased under phosphate starvation,while the content of Acid phosphate enzyme and Proline content were increased under the low phosphate stress.At the same time,a large number of phosphorus transporter genes were differentially expressed under low phosphorus stress,among which Pho1 family had higher differentially expressed genes.Our study laid a molecular basis for further study on the changes of phosphate transporter genes under low phosphate stress.3.ESI-MS/MS was performed on roots of maize seedlings with 3,7 and 14 days of low phosphate stress.Six phospholipids,two galactolipids,one sulfatide,three lysophospholipids and Glc ADG were detected.The content of phospholipids PC and PE in maize roots was the most abundant.The percentage of phospholipids(PC、PE、PI、PS、PG)were decreased,the content of DGDG and MGDG increased under low phosphate stress,and the contentof Glc ADG were also increased.The 36:6 molecular species of DGDG and MGDG are the most abundant,indicating that the synthesis of maize galactolipid is completely dependent on the eukaryotic pathway and is a typical feature of 18:3 plants.4.The metabolic pathways of “phospholipid signal” and “Fatty Acid Elongation &Wax Biosynthesis” were significantly enriched Among the lipid-related genes from the transcriptome data.At the same time,the differential expression of type B glycolipids and thiolipids synthetic genes was obvious under low phosphorus stress.Combining the transcriptome data and lipidome data,it was found that low phosphorus stress activated the phospholipid metabolic pathway,the de novo synthesis pathway of glyceroglycolipid in the chloroplast and the synthesis pathway of glycolipid Glc ADG.Based on the results of transcriptome,physiology and lipidome data,a gene-metabolite interaction network diagram of maize root membrane lipid metabolism under low phosphorus stress was initially established.The study also provides a theoretical basis for further exploration of the physiological and membrane lipid metabolism regulation patterns. |
