This document discusses the uptake mechanisms of nitrogen, phosphorus, and iron in plants. It explains that nitrogen is taken up through NRT1 and NRT2 gene families, phosphorus through PHT transporters, and iron through either a reduction or chelation strategy. Maintaining the proper balance of nutrients is important for plant growth and high yields, though excessive fertilizer use can harm the environment. Understanding nutrient uptake mechanisms and their regulation can help improve crop nutrient use efficiency and yields.

1. Donaka suneel
2019617005

2. INTRODUCTION
 Plants require a complex balance of mineral nutrients
to reproduce successfully. Because the availability of
many of these nutrients in the soil is compromised by
several factors, such as soil pH, cation presence, and
microbial activity, crop plants depend directly on
nutrients applied as fertilizers to achieve high yields.

3.  Excessive use of fertilizers is a major environmental
concern due to nutrient leaching that causes water
eutrophication and promotes toxic algae blooms.
 Mineral elements, such as phosphorus (P), nitrogen
(N), calcium (Ca), iron (Fe), zinc (Zn), magnesium
(Mg), and manganese (Mn) play essential roles in all
living organisms.

4.  An ap-propriate balance of all these nutrients is
necessary at each stage of plant development to
achieve maximum yield. Plants require large amounts
of P and N that are key nutrients because they are
building blocks for fundamental biological molecules,
such as nucleotides, amino acids, and proteins,
whereas they need only small amounts of
micronutrients, such as Fe, Zn, and boron, which
generally act as cofactors in enzymatic reactions

5. Uptake mechanisms of some of the nutrients.
 Nitrogen uptake mechanism
 Phosphate uptake mechanism
 Iron uptake mechanism

6. Nitrogen uptake mechanism
There are four NO3-transporter gene families are
known, of which NITRATE TRANSPORTER1/PEPTIDE
TRANS-PORTER (NRT1/PTR) and NITRATE
TRANSPORTER2 (NRT2) gene families are responsible
for NO3- uptake from the environment.

7.  The dual-affinity member of the NRT1/PTR gene family,
NRT1.1 also called CHLORATE RESISTANT1 [CHL1]), and
the NRT2.1, NRT2.2, and NRT2.4 members of the NRT2
gene family are HATS particularly important under low
NO3- availability. In addition to their transport function,
NRT1.1 and NRT2.1 are also involved in NO3-sensing.
 CALCINEURIN B-LIKE-INTERACTING PROTEIN
KINASE23 (CIPK23)

8. Transporters and regulatory elements involved in nitrate metabolism.

9. Phosphate uptake mechanism
Pi uptake from the rhizosphere is a function carried
out by proton (H+)/Pi symporters, simply called Pi
transporters. To date, four gene families of Pi
transporters (PHT1, PHT2, PHT3, and PHT4) have
been identified in Arabidopsis

10.  In Arabidopsis, overexpression of PHOSPHATE
STARVATION RESPONSE1 (PHR1), a master TF
controlling a large subset of Pi stress-responsive genes,
including PHT genes, resulted in a 2.5- and 4-fold
increase in shoot Pi accumulation, under Pi-sufficient
and Pi-stress conditions,

11. Schematic representation of the phosphorus uptake
and assimilation processes

12. Schematic representation of the performance of a phosphite (Phi)
fer-tilization scheme in comparison to a conventional (phosphate)
(Pi) fer-tilization

13. Iron uptake mechanism
 Although Fe is not required in high amounts by plants,
its low solubility in agricultural soils greatly affects
crop yield, especially in alkaline soils. In nature, free Fe
con-centration at neutral pH is in the range of 10-17 M,
which would cause Fe-deficiency symptoms because
the required amount for optimal plant growth is
between 10-9 to 10-4 M

14.  Schematic representation of the two main iron uptake
systems in plants.
REDUCTION STRATEGY
CHELATION STRATEGY

15. Schematic representation of the two main iron uptake
systems in plants

16.  The root system is central for water and nutrient
uptake; therefore, understanding the mechanism that
control root system architecture as well as its
interaction with the rhizosphere compo-nents that
influence nutrient availability, will help to improve
nutrient use efficiency of any crop plant.
CONCLUSION