This document provides an overview of salinity tolerance and breeding strategies for soybeans. It discusses the physiological effects of salt stress on crops, outlines important salt tolerance genes that have been mapped in soybean, and describes the salinity conditions in South Korea where soybean breeding is focused. The document then details breeding strategies used for developing salt tolerant soybean varieties, including conventional breeding methods like hybridization, backcrossing, and multi-location trials, as well as molecular breeding techniques like marker-assisted selection. The goal is to develop soybean varieties that can be grown successfully on reclaimed tidal lands in South Korea affected by soil salinity.

1. Salinity tolerance and
breeding strategies on soybean
Presented by:
Bishnu Adhikari
Student Id: 2016226596
Plant Resources Development Lab
7 June 2016

2. Outlines
• Introduction
• Physiological effects
• Salt tolerant varieties of different crop
• Important genes mapped in soybean
• Salinity condition in Korea
• Breeding strategy for salinity tolerance in
soybean
• Conclusion

3. What is soil salinity?
Introduction
Soil containing enough soluble salts to reduce its
fertility and interfere with crop growth.
Salt-affected soils can be divided into saline, saline-
sodic and sodic, depending in salt amounts, type of
salts, amount of sodium present and soil alkalinity.
Each type of salt-affected soil will have different
characteristics.
Soil salinity is one of the important abiotic
components that frequently have critical effects on
crop growth, productivity and quality
Iran salt affected soil
China salt affected soil

4. What are the salt-affected soils?
Salt-
affected
types
Electrical
Conductivity
(dS/m)
Exchangeable
Sodium
Percentage
(ESP)
Sodium
Adsorption
Ratio(SAR)
pH
Saline >4 <15 <13 <8.8
Sodic <4 >15 >13 8.5-
10.5

5. Why does soil become salinity?
1.Semiarid and arid regions
Annual precipitation< evapotranspiration
2.Natural sources of soil salinity
a) Mineral weathering
b) Fossil salts
c) Atmospheric precipitation
Introduction (contd…….)

6. 3.Local salt accumulation
Soils in low-lying areas
4.Human Activities
a. Salts from areas of over-irrigation accumulate in
poorly drained areas.
b. Relatively saline irrigation water are used.
c. Oil-field development, waste-spreading operation,
and crop fertilization
Evaporation
Capillary rise
water table

7. Extent of Salt affected land
• As agricultural land is increasingly salinized through
inefficient fertilizer practices, salt-water intrusion, and use
of poor quality irrigation water (Abel and MacKenzie,1964).
• 50% of the arable land will be affected by salt stress by 2050
(Blumwald and Grover,2006).
• Ocean contain 97% of total water supply in the world with major
component of NaCl (500 molm-3) which is highly toxic to normal
plants.
• Globally the total area of saline soils is 397 million ha and sodic
soils 434 million ha. Out of 230 million ha irrigated land, 45 million
ha (19.5 %) were salt-affected soils and almost 1500 million ha of
dryland agriculture, 32 million (2.1 %) were salt-affected soils (FAO,
2016).
• The regional impact of salinity is much serious than the average
value. For e.g. Pakistan, Australia(Ahmad, 1990; Northcote &
Skene, 1972)

8. Physiological effects of Salt Stress
Germination
• Increased osmotic pressure of the soil solution which restricts the absorption
and entry of water into the seeds.
• Certain salt constituents like CO3
-2, NO3
-
,Cl
-
, SO4
-2 are more harmful to seed
germination.
• Hampers the metabolism of stored materials
Vegetative growth
• Closure of stomata leads to reduction in CO2 assimilation and
transpiration.
• Reduced turgor potential affects the leaf expansion.
• Decreased rate of leaf growth due to osmotic effect of salt around
roots,
• Leaf cells loose water
• Reductions in cell elongation and cell division
Total 444 M ha

9. Photosynthesis
• Accumulation of high concentration of Na+ and Cl- in chloroplast,
photosynthesis is inhibited
• Photosynthetic enzyme for carbon assimilation are very sensitive to the
presence of NaCl
Nitrogen Metabolism
• The key enzyme, nitrate reductase is very sensitive to NaCl .
Reproductive growth and yield
• Onset of flowering is delayed due to the limitations of source size.
• Quantum of reproductive structure such as number of flowers is very much
reduced.
• Affects the mobility of metabolites.
• Hormone synthesis is hampered
• Seed oil content decreases

10. Effect of salt stress on crop growth & development
Morphologically
Stunted
Chlorosis
Wilted
Senescence
Physiologically
Lowering of osmotic
pressure,
Lowering antioxidants
Genetically by
biosynthesis of
specific proteins for
salt stress

11. Salt tolerance degree of some important crops
Crop Threshold salinity level (EC ds/m)
Tolerant crops
Barley 8.0
Sugar beet 7.0
Moderately tolerant crops
Soybean 5.0
Cowpea 4.9
Moderately sensitive crops
Rice 3.0
Tomato 2.5
Sensitive crops
Orange 1.7
Bean 1.0
(Ashraf & Wu, 1994)

12. A soybean salt-tolerant plant compared to a non-tolerant variety
(Guan et al. 2014)

13. Important genes mapped in soybean
Trait Gene
Aphid Resistance Rag1
Bacterial Blight Rpg1,Rpg4
Salt tolerance GmDREBa, GmDREBb,
GmDREBc, GmSALT3 ,Ncl2
Fatty acid(Linolenic acid) GmFAD3,Fan Fas
Flower color W1,Wp,gmfls1
Salt stress GmPAP3,GmCAX1
Soybean mosaic virus Rsv1,Rsv4
Soybean rust Rpp1

14. Some of the salt tolerant varieties /lines of different crops
Crops Salt tolerant varieties/lines
Barley Selection from composite cross XXI
Rice Pokkali, Johna 349, Kala rata, Damodar, Benisail, Nonabokra
Sorghum Double TX
Tomato Selection line from the cross
L. esculentum × L. cheesmanii
Wheat Kharchia, LU-26S Accessions 178704,178012,180988
Soybean S-100, Lee, Tiefeng 8, Wenfeng 7, Jindou, Wild Soybean
Accession PI483463

15. Salinity condition in Korea
Why salinity tolerant soybean in Korea?
• Reclaimed tidal lands that locate mainly in west and south
coastal areas of Korean peninsula are approximately 350,000
ha, which occupy about 21% of arable lands for crop
production (Lee et. al., 2013).
• The importance of reclaimed tidal lands is gradually increasing
in Korea because stable food production is fundamental in
response to increasing world population and improvement of
living standard (UN, 2013).
• Reclamation and preventable measures for transforming salt
affected lands into arable land are very expensive.
• Breeding approach to overcome salinity problems seems to be
the only economic and efficient alternative.

16. Breeding Strategies for salinity
tolerance in soybean
Conventional Breeding
• Introduction
• Selection(Mass
selection/Pure line Selection)
• Hybridization
 Pedigree
 Bulk method
 SSD method
 Back cross
 Multiple crossing
Molecular Breeding
• Marker Assisted Selection
(MAS)
• Marker Assisted Backcross
(MABC)
• Marker Assisted Pyramiding
• Marker Assisted Recurrent
Selection (MARS)
• Quantitative Trait Loci (QTL)
• Genomic Selection

17. What is Marker Assisted Selection (MAS)?
A process whereby a marker is used for selection of a genetic
determinants of a trait of interest like disease resistance, tolerance to
abiotic stresses and quality traits.
First direct benefit that breeders obtained from genomics and being
applied successfully in molecular breeding for genetic improvements
of many major crops including soybean.
MAS can enhance conventional breeding in
 early selection of traits
 independent to season and location for the trait
 gene pyramiding
 recovery of recurrent parent
 selection of parental lines with wider genetic base
 monitoring seed purity and germplasm identity
Types of markers: RFLPs, SCARs, STS, SSRs & more recently SNPs
.

18. • There is complex polygenic trait controlling stress tolerance,
however salt tolerance in soybean is a single dominant
gene.
• Abel (1969) reported that a single dominant gene controlled
salt tolerance in the soybean cultivar Lee which is derived
from S-100 × CNS with S-100.
• Lee JD et al. (2009) identified one major QTL Ncl2 in G.
soja line PI483463 for salt tolerance, which was associated
with markers sat_091, satt237 and satt339 on linkage group
N (Chr. 3).
Breeding Strategies contd….

19. • For hybridisation, modest resistance species closer to the
cultivated crops should be chosen in the context of stress
tolerance (not only salinity tolerance) as ecological
adaptations and agronomic objectives need to be mutually
inclusive.
• For breeding of soybean salinity tolerant ‘Daepung2ho’ and
‘Uram’ cultivars are taken as recurrent parent and Wild
Soybean (Glycine soja Sieb. and Zucc.) Accession PI483463 is
taken as donor parent.
• Daepung2ho is a cultivar of the highest yield (3450 Kg/ha) in
Korea which is tolerant to lodging, fire blight and seed
shattering.
• Uram is another high yield cultivar (3270 Kg/ha) and has
merits of suitability to mechanized farming and fire blight
resistance (RDA 2011).
Breeding Strategies contd….

20. Bulk method
Line PI483463 Daepung2ho/Uram
(Donor parent) (Recurrent parent)
F2
F3
F1
F4
……….…..
F7 (Preliminary Yield Trials)
Multi location trial and yield and other traits evaluation
Release new salinity tolerant line/variety
(Reclaimed tidal lands)
Grown in
naturally
saline field
conditions

21. Backcross method
Salt tolerant Line PI483463(P1 ) X Daepung2ho/Uram (P2)
1st Backcross
( 50% genes from P2)
F1 X Daepung2ho/Uram
2nd Backcross
( 75% genes from P2)
BC1 X Daepung2ho/Uram
3rd Backcross
( 87.5% genes from P2)
BC2X Daepung2ho/Uram
4th Backcross
( 93.75% genes from P2)
BC3X Daepung2ho/Uram
5th Backross
(96.875% genes from P2)
BC4
Self replication
(Homogygous with P2)
BC4F2
Preliminary trial BC4F2 lines are evaluated for important characters
in comparison with the recurrent parent(P2)
Multi-location trial Grow in different reclaimed tidal lands that locate
mainly in west and south coastal areas of Korea
Grown in
naturally
saline field
conditions
(High yielding cultivars in korea)

22. Backcrossing by molecular marker
DNA
Marker
PI483463 Daepung
2ho/Uram
F1
NCL2 ncl2
F1
PI483463 (P1) X Daepung2ho/Uram (P2)
(Non-recurrent parent) (Recurrent parent)
BC1F1
P2
X
P2
X
BC2F1 P2X
BCnF1
Segregation in BCnF2 line
NCL2NCL2 NCL2ncl2 ncl2ncl2 NCL2NCL2 NCL2NCL2 NCL2ncl2 ncl2ncl2 NCL2NCL2 NCL2NCL2 NCL2ncl2
Test for the presence of the
homozygosis alleles from
the donor
In each BC
generation test
whether the
parents are true
BC or maternal
self
In each BC
generation test
presence of the
desirable alleles
of the parents.
single dominant gene Ncl2
NCL2ncl2
Grown in
naturally
saline field
conditions

23. Multi-location trials in reclaimed tidal land
• Reclaimed tidal lands of South Korea are Hwaseong, Saemangeum
and Yongsan-gang area. (Lee et al., 2014)
Hwaseong
Saemangeum
Yongsan gang

24. • Many arable land are being lost from crop production due to
increasing soil salinity.
• Genes for salt tolerance of plant have been identified by
molecular analysis.
• Development of salt tolerant cultivars becomes increasingly
important as a means of combating salt-related yield losses.
• The greatest advancement in the genomic tools is the use of
molecular markers for MAS
• In addition to conventional breeding techniques various
modern genetic engineering techniques and recombinant
DNA techniques may have role in the crop salinity tolerance.
Conclusion

25. References
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698.
Abel GH, MacKenzie AJ (1964) Salt tolerance of soybean varieties (Glycine max L. Merrill) during germination and later growth.
Crop Sci 14:157–161
Ahmad S. (1990). Soil salinity and water management. In proceedings of the Indo-Pak workshop on soil salinity and
water management. pp.3-18 (PARC:Islamabad)
Ashraf M (1994). Breeding for salinity tolerance in plants. Crit. Rev. Plant Sci. 13, 17–42.
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crops, Nigel G. Halford, eds., John Wiley and Sons Ltd, UK, pp. 206–224.
Food and Agriculture Organization 2016
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Hong-Kyu; 2014 Characteristics of Newly Reclaimed Tidal Land and Its Changes by Cultivation of Green Manure
Crops
Northcote,K.h., and Skene, J.K.M. (1972). Australian soils with saline and sodic properties. Soil publication No. 27.
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26. Thank you all for your Kind
attention