Abstract
Nitrogen (N) is probably the most important macronutrient and its scarcity limits plant growth, development and fitness. N starvation response has been largely studied by transcriptomic analyses, but little is known about the role of alternative polyadenylation (APA) in such response. In this work, we show that N starvation modifies poly(A) usage in a large number of transcripts, some of them mediated by FIP1, a component of the polyadenylation machinery. Interestingly, the number of mRNAs isoforms with poly(A) tags located in protein-coding regions or 5′-UTRs significantly increases in response to N starvation. The set of genes affected by APA in response to N deficiency is enriched in N-metabolism, oxidation-reduction processes, response to stresses, and hormone responses, among others. A hormone profile analysis shows that the levels of salicylic acid (SA), a phytohormone that reduces nitrate accumulation and root growth, increase significantly upon N starvation. Meta-analyses of APA-affected and fip1-2-deregulated genes indicate a connection between the nitrogen starvation response and salicylic acid (SA) signaling. Genetic analyses show that SA may be important for preventing the overgrowth of the root system in low N environments. This work provides new insights on how plants interconnect different pathways, such as defense-related hormonal signaling and the regulation of genomic information by APA, to fine-tune the response to low N availability.
Highlights
IntroductionDifferent N compounds can be found in soil, nitrate (NO3 − ) is the major N source for higher
Nitrogen (N) is a key mineral nutrient that plays a crucial role in plant growth and development. different N compounds can be found in soil, nitrate (NO3 − ) is the major N source for higherPlants 2020, 9, 251; doi:10.3390/plants9020251 www.mdpi.com/journal/plantsPlants 2020, 9, 251 plants and one of the most assimilable N-based compound [1]
We have found that the fip1-2 mutant, which has defects in polyadenylation [12], is less sensitive to the root growth inhibition promoted by N deficiency and has a lower induction of NRT2.4 transporter
Summary
Different N compounds can be found in soil, nitrate (NO3 − ) is the major N source for higher. Plants 2020, 9, 251 plants and one of the most assimilable N-based compound [1]. Under low N conditions, to guarantee the search and influx of N into the roots, plants induce a large number of genes, many of them involved in N acquisition and N usage efficiency. To cope with N acquisition, high and low affinity NO3 − transport systems, HATS and LATS, respectively, have evolved during evolution [6]. The expression of one of these high affinity transporters, NRT2.4, is rapidly induced by N starvation [7], and can be used as a N starvation marker in plants
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