2 research outputs found
New insights on arabidopsis thaliana root adaption to ammonium nutrition by the use of a quantitative proteomic approach
Nitrogen is an essential element for plant nutrition. Nitrate and ammonium are the two
major inorganic nitrogen forms available for plant growth. Plant preference for one or the other
form depends on the interplay between plant genetic background and environmental variables.
Ammonium-based fertilization has been shown less environmentally harmful compared to nitrate
fertilization, because of reducing, among others, nitrate leaching and nitrous oxide emissions.
However, ammonium nutrition may become a stressful situation for a wide range of plant species
when the ion is present at high concentrations. Although studied for long time, there is still an
important lack of knowledge to explain plant tolerance or sensitivity towards ammonium nutrition.
In this context, we performed a comparative proteomic study in roots of Arabidopsis thaliana plants
grown under exclusive ammonium or nitrate supply. We identified and quantified 68 proteins with
differential abundance between both conditions. These proteins revealed new potential important
players on root response to ammonium nutrition, such as H+
-consuming metabolic pathways
to regulate pH homeostasis and specific secondary metabolic pathways like brassinosteroid and
glucosinolate biosynthetic pathways
Root phosphoenolpyruvate carboxylase activity is essential for Sorghum bicolor tolerance to ammonium nutrition
Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is an enzyme family with pivotal roles in plant carbon and
nitrogen metabolism. A main role for non-photosynthetic PEPC is as anaplerotic enzyme to load tricarboxylic
acid (TCA) cycle with carbon skeletons that compensate the intermediates diverted for biomolecule synthesis
such as amino acids. When plants are grown under ammonium (NH4
+) nutrition, the excessive uptake of NH4
+
often provokes a stress situation. When plants face NH4
+ stress, N assimilation is greatly induced and thus, requires the supply of carbon skeletons coming from TCA cycle. In this work, we addressed the importance of root
PEPC and TCA cycle for sorghum (Sorghum bicolor L. Moench), a C4 cereal crop, grown under ammonium
nutrition. To do so, we used RNAi sorghum lines that display a decrease expression of SbPPC3 (Ppc3 lines), the
main root PEPC isoform, and reduced root PEPC activity. SbPPC3 silencing provoked ammonium hypersensitivity, meaning lower biomass accumulation in Ppc3 respect to WT plants when growing under ammonium
nutrition. The silenced plants presented a deregulation of primary metabolism as highlighted by the accumulation of NH4
+ in the root and the alteration of normal TCA functioning, which was evidenced by the accumulation of organic acids in the root under ammonium nutrition. Altogether, our work evidences the importance of
non-photosynthetic PEPC, and root TCA cycle, in sorghum to deal with high external NH4
+ availability.Gobierno Vasco - IT1560-22Consejería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía. Programa Operativo FEDER 2014–2020 - US- 1251626MCIN/AEI/10.13039/501100011033 y FEDER - AGL2016-75413-P y BIO2017-84035-RMCIN/AEI/10.13039/501100011033 - PRE2018-08526