It is important to understand the inheritance pattern of genes that are linked to nutrient uptake and assimilation.

1. Breeding for nitrogen use efficiency in
cereals
Presented by
Sachin Kumar H M
MAITAFO182
MSc Agri (GPB)25/11/2017 Dept of Genetics and Plant Breeding 1

2. Introduction
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3. Nitrogen is essential component of
Chlorophyll
Enzymes
Proteins Nucleic acids
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4. Why we need to go for breeding
NUE
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6. NUE of different cereals
0
5
10
15
20
25
30
35
40
45
50
Wheat Rice triticale Barley Maize oat
Series 1
Wheat
Rice
triticale
Barley
Maize
oat
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7. Effects of excess of nitrogen fertilizer
application
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Eutrophication Lodging
DiseasesFertilizer burn

8. Deficiency of nitrogen
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Yellowing of basal leaves
Chlorosis
Decrease in Kernel color
Stunted growth

9. Definitions
NUE: Nitrogen use efficiency is the
grain production per unit of N
available in soil and applied
externally.
Grain yield
(Available N in soil + applied
fertilizer)
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NUE =

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NUE
Nitrogen uptake
efficiency
Nitrogen utilization
efficiency
(plant (or shoot) N content)
UpE =
(N supply)
(grain mass)
UtE =
(plant (or shoot) N content)

11. Physiological basis of NUE
• Nitrogen uptake
• Nitrogen assimilation
• Transamination
• Remobilization
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Nitrogen cycle

13. Nitrate uptake
Low affinity transport
system
high affinity transport
system
No
-3
No
-3
No
-3
No
-3
No
-3
No
-3 No
-3
No
-3
No
-3
No
-3
No
-3
No
-3
No
-3
No
-3 No
-3
No
-3
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14. Nitrogen assimilation
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15. Transamination
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16. Remobilization
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Remobilization
Protease
Chloroplast
protein
Amino acids
Transamination
GDHGlutamate pool 2-Oxaloglutarate Ammonia
AMT

18. Transporter genes Genes
Nitrate transporter gene (High
affinity )
NRT2.1, 2.2, 2.3, 2.4
Nitrate transporter gene (low
affinity)
NRT1 or NPF
Ammonium Transporter AMT1.1, 1.2
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Molecular basis of NUE
N Assimilation genes
NR Nitrate reductase NR1, NR2
NiR Ferredoxin-nitrite
reductase
NiR1, NiR2

19. Gene family Genes
GDH GDH1, GDH2, GDH3,
GDH4
GS GS1, 2, 3, 4, 5
GOGAT GOGAT1, 2
Aminoacid Biosynthesis Genes
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Nitrogen uptake governing genes

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Location of detected QTLs for physiological traits
governing NUE

22. Case study

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Results

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25. Genetic basis of NUE
Nature of gene action for nitrogen use efficiency (NUE)
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Type of Gene action Authors
Additive gene action Mc Kendry et al., 1988
Additive and Non additive in F1 hybrids Le Gouis et al., 2002
Additive action for F2 progenies of wheat Yildirim et al., 2007

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Case study

27. • 6 x 6 diallel at low and high N levels.
• Mean squares of GCA and SCA significant
under both low-N and high-N
• GCA > SCA
• Additive genetic variance > non-additive
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28. Traits correlated with NUE
Chlorophyll content
Dry weight of root
Dry weight of shoot
Grain weight
Harvest index
Number of productive tillers
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29. Strategies to improve NUE
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Conventional breeding approaches
• Selection
• Backcross
Molecular and genetic engineering approaches
• Quantitative Trait Loci and Candidates Genes
• Transgenes for NUE

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• GS1/Gln : Gln1-3 and Gln1-4 genes
• Gln1-3: Kernel number and Gln1-4 : Kernel size
• Mutants :
 Gln1-3 mutant : Gln1-3 gene was silenced
 Gln1-4 : Gln1-4mutant : Gln1-4 gene was silenced
 Gln1-3/1-4 mutant: Gln1-3 and Gln1-4 gene were
silenced.
 Transgenic Gln3 & Gln4
Case study

32. Results
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