Plant scientists at NYU have discovered how plants perceive nitrogen availability and adjust their growth accordingly. The breakthrough may ultimately lead to ways to enhance plant growth while reducing the need for harmful and costly fertilizers.
Crop yield can be increased with fertilizer, but the molecular link between a higher dose of nitrogen and greater plant biomass has been a mystery.
A team of experts at the NYU Center for Genomics & Systems Biology examined plants to investigate how increasing doses of nitrogen may trigger changes in genetic expression over time. Next, the researchers used mathematical models to analyze the rate of change in messenger RNA (mRNA) for thousands of genes.
The study revealed that the dynamics of mRNA responses to nitrogen dose were regulated by enzyme kinetics, or enzyme reaction rates, principles that were first described by Michaelis-Menten in 1913.
The researchers discovered that the Michaelis-Menten kinetics model could accurately represent the rate of changes in gene expression among 30 percent of nitrogen-dose responsive genes.
“According to the classic Michaelis-Menten kinetic model, changing enzyme abundance will impact the maximum rate of reaction possible. Because transcription factors establish the rates at which gene transcription from DNA into RNA takes place, they can be directly compared to the catalytic enzymes in the Michaelis-Menten model,” explained study senior author Professor Gloria Coruzzi.
“This means that increasing the abundance of key transcription factors should be able to boost the rate of nitrogen-dose dependent gene expression and, as a consequence, the rate of plant growth.”
Experiments showed that increasing the level of the transcription factor TGA1 accelerated the rates of nitrogen-dose responsive gene expression and the rate of plant growth. In response to nitrogen, the plants that overexpressed TGA1 achieved a plant biomass three times greater than wild plants.
“By modeling the transcriptome kinetics underlying nitrogen-dose sensing using a classic principle of Michaelis-Menten kinetics, we discovered a regulatory gene whose increased expression may boost crop growth within low-nitrogen soils,” said Professor Coruzzi.
“Because TGA1 is conserved in plants, including crops such as rice, tomatoes, and wheat, our findings have implications for improving nitrogen use efficiency in crops, which can benefit agriculture and sustainability.”
The study is published in the journal PNAS.