News has recently emerged from the National Centre of Biological Sciences, Tata Institute of Fundamental Research in Bengaluru that researchers have discovered a new pathway. This pathway is crucial as it regulates the absorption of nitrates in plants.
The researchers focused on a specific miR444 target gene known as MADS27. This is noteworthy because this transcription factor has historically received minimal attention. Transcription factors are proteins which play a significant role in transcribing DNA into RNA. This group hosts numerous proteins, excluding RNA polymerase, and they initiate and manage the transcription of genes.
The gene MADS27 is activated by the micro-RNA, miR444. Once activated, MADS27 controls nitrate absorption, root development and stress tolerance. This offers a method to manipulate these key plant properties. Interestingly, MADS27 might be an optimal candidate for modification in order to increase nitrogen use efficiency. This would help the plant absorb more nitrates and create abiotic stress tolerance. This mechanism has been studied in both rice (monocot) and tobacco (dicot) plants by the researchers. The study was published in the Journal of Experimental Botany.
The Significance of Nitrogen
Nitrogen is one of the most essential macronutrients required for plant development. However, overuse of nitrates in fertilisers can lead to a build-up in the soil. This excess nitrogen then accumulates in water and soil, leading to pollution and increased greenhouse gas emissions.
Importantly, nitrogen contributes to many key components of plants including chlorophyll, amino acids and nucleic acids. It is primarily sourced from the soil where plant roots absorb it in the form of nitrates and ammonium. The presence of nitrates significantly affects genome-wide gene expression, which then impacts the plant’s root system, biological clock, leaf growth and more.
Adding Nitrogen to Soil
There are several ways that nitrogen can be added into soil. Mammals, including humans, excrete urea, a primary nitrogenous waste product. They are referred to as ureotelic animals and their waste contributes to the nitrogen content in soil.
Contrary to this, burning coal does not directly add nitrogen to the soil. The combustion process produces various oxides and byproducts such as fly-ash, flue gas and scrubber sludge, but no direct nitrogen contribution.
Lastly, when plants and animals die, their decomposing organic matter releases nitrogen compounds back into the soil. Microorganisms in the soil break these down further, producing ammonia which then transitions into nitrites and nitrates via a process called nitrification. Thus, the death of vegetation is another way that nitrogen can be reintroduced into the soil.