Abstract
BackgroundMaize (Zea mays L.) is one of the most widely cultivated crop plants. Unavoidable economic and environmental problems associated with the excessive use of phosphatic fertilizers demands its better management. The solution lies in improving the phosphorus (P) use efficiency to sustain productivity even at low P levels. Untargeted metabolomic profiling of contrasting genotypes provides a snap shot of whole metabolome which differs under specific conditions. This information provides an understanding of the mechanisms underlying tolerance to P stress and the approach for increasing P-use-efficiency.Methodology/Principal FindingsA comparative metabolite-profiling approach based on gas chromatography-mass spectrometry (GC/MS) was applied to investigate the effect of P starvation and its restoration in low-P sensitive (HM-4) and low-P tolerant (PEHM-2) maize genotypes. A comparison of the metabolite profiles of contrasting genotypes in response to P-deficiency revealed distinct differences among low-P sensitive and tolerant genotypes. Another set of these genotypes were grown under P-restoration condition and sampled at different time intervals (3, 5 and 10 days) to investigate if the changes in metabolite profile under P-deficiency was restored. Significant variations in the metabolite pools of these genotypes were observed under P-deficiency which were genotype specific. Out of 180 distinct analytes, 91 were identified. Phosphorus-starvation resulted in accumulation of di- and trisaccharides and metabolites of ammonium metabolism, specifically in leaves, but decreased the levels of phosphate-containing metabolites and organic acids. A sharp increase in the concentrations of glutamine, asparagine, serine and glycine was observed in both shoots and roots under low-P condition.ConclusionThe new insights generated on the maize metabolome in resposne to P-starvation and restoration would be useful towards improvement of the P-use efficiency in maize.
Highlights
Phosphorus (P), as phosphate, is an integral component of a number of important compounds present in plant cells, such as the sugar-phosphates used in respiration and photosynthesis and the phospholipids that make up plant membranes
The primary aim of this study was to dissect the mechanism of genotypic variation in maize in response to P stress condition based on changes in metabolic pathways
Growth performance of 33 maize genotypes at sufficient and low-P levels was analysed by principal component and cluster analysis taking into consideration 15 trait variables as mentioned above
Summary
Phosphorus (P), as phosphate, is an integral component of a number of important compounds present in plant cells, such as the sugar-phosphates used in respiration and photosynthesis and the phospholipids that make up plant membranes. It is a component of nucleotides used in plant’s energy metabolism and in the DNA and RNA molecules. Untargeted metabolomic profiling of contrasting genotypes provides a snap shot of whole metabolome which differs under specific conditions. This information provides an understanding of the mechanisms underlying tolerance to P stress and the approach for increasing P-use-efficiency
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