Download - Seminar Presentation-Moon
Seminar on Molecular studies and
breeding approaches of salt tolerance in rice
(Oryza sativa)
Presented by:Nushrat Jahan Moon
Reg no: 05-01837Department of Genetics & Plant Breeding
What is soil salinity?
Soil containing enough soluble salts to reduce its fertility and interfere with crop growth.
These soils are two types:
Saline soil and Sodic soil(or alkali)
Introduction
What are the salt-affected soils ?
Salt-affected types
Electrical Conductivity ECe (dS/m)
Exchangable Sodium PercentageESP (%)
Sodium Absorption Ration (SAR)
pHs
Saline >4 <15 <13 <8.8
Sodic <4 >15 >13 8.5-10.5
Introduction (continued)
Source: http://www.knowledgebank.irri.org/ricebreedingcourse/breeding_for_salt_tolerance.htm
Extent of salt affected soils
Sodic
Saline
Asia, Pacific and Asia, Pacific and Australia (M ha)Australia (M ha)
Source : FAO database
195 249
Total 444 M ha
Introduction (continued)
Objectives To get an idea about advanced research works on salt tolerance of rice.
To exploit different molecular breeding strategies for the development of salt tolerant rice varieties.
Expression of salt stress on rice
Stress status Soil pH Electrical conductivity
Salinity status
Non-stress pH 8.8 - 9.2 Beyond ECe ~ 4 dS/m
Moderate
Moderate 9.3 – 9.7 More than 8 dS/m
High
Higher Equal or > 9.8 -- Very high
Source: http://www.knowledgebank.irri.org/ricebreedingcourse/breeding_for_salt_tolerance.htm
Physiology: Traits associated with salinity tolerance
Degree of salt stress can affect the different crops differently
Modified standard evaluation score (SES) of visual salt injury at seedling stage
Observation Tolerance
Normal growth, no leaf symptoms Highly tolerant
Nearly normal growth, but leaf tips
Or few leaves whitish and rolled
tolerant
Growth severely retarded; most leaves
rolled; only a few are elongating
Moderately tolerant
Complete cessation of growth; most
leaves dry; some plants dying
Susceptible
Almost all plants dead or dying Highly susceptible
Source: http://www.knowledgebank.irri.org/ricebreedingcourse/breeding_for_salt_tolerance.htm
Manifestation of Salt Stress
Morphological Symptoms White leaf tip followed by tip burning (salinity) Leaf browning & death (sodicity) Stunted plant growth Low tillering Spikelet sterility Low harvest index Less florets per panicle Less 1000 grain weight Low grain yield Change in flowering duration Leaf rolling White leaf blotches Poor root growth
“Ultimate death of leaf – always from oldest to
youngest”
Salinity symptoms at the vegetative stage
Effect of salinity at Reproductive stage – Spikelet Sterility
Effect of salinity at Reproductive stage – papery sterile spikelets
Manifestation of Salt Stress
Physiological & Biochemicalv High Na+ transport to shootv Preferential accumulation of Na in older leavesv High Cl- uptake v Lower K+ uptake v Lower fresh and dry weight of shoot and rootsv Low P and Zn uptakev Increase of non-toxic organic compatible solutesv Increase in Polyamine levels
Basic Concepts – Genotype vs. phenotype
Plant breeding is based upon most basic yet most important genotype and phenotype relationship (William Johannsen, 1903)
Genes cannot push a trait to develop unless appropriate environment is provided
No amount of manipulation can cause a phenotype to develop unless necessary genes(s) are present
Breeding Strategy
Conventionalbreeding• Introduction• Selection • Hybridization• Pedigree• Bulk• SSD method
Molecular breeding
• MAS
• QTLs
• Somaclonal approach
• Anther culture
• Genetic transformation
What is MAS?
Marker assisted selection (MAS) is a process whereby a marker is used for selection of a genetic determinant or determinants of a trait of interest.
Progress of Saltol locus
• Saturated map of the Chromosome 1 (Saltol segment) is developed
• Closely linked markers linked to the saltol locus identified
• MAS is being validated in 3 breeding
populations
AP3206
RM3412CP03970
RM8094RM493CP6224
RM140
(Source: Glenn B. Gregorio,2002)
RM283
R844S2139
RM246
RM237
RM23RM140
C17RM113S1715
S13994RM9
R2374BRM5
C1456
0.0
27.4
129.9
60.6
123.5
119.5
103.1
99.1
98.291.9
40.0
28.4
64.9
66.271.2
75.377.2
Short arm of chromosome 1
C52903S
A
What is QTLs?
Quantitative Trait Loci (QTLs) is a
location on a chromosome
which regulate phenotype for
quantitative trait and is determined by a
number of genes.
List of genes that are located in the region of QTL and up-regulated by high salinity in rice
Gene name Insertion linesClone ID full length cDNA
References
Pectinesterase 1B-23740,
1B-23741
CG408589
Ak105998
Ser/thr kinase AK065231 Guo et al., 2001
Phospholipase D 1515 AK120868 Kacperska, 2004
Zhu, 2002
SecA/protein transport factor
CL520490
CL520492
AK070488
Peroxidase AK099187 Pastori and Foyer, 2002
Sottosanto et al., 2004
Alkaline Invertase AK120720
Unknown cDNA AK099887
Source: http://www.knowledgebank.irri.org/ricebreedingcourse/breeding_for_salt_tolerance.htm
• Agrobacterium mediated transformation• Particle bombardment (gun)• PEG-mediated• Electroporation• Silicon carbide fibers
Methods of genetic transformation
Agrobacterium mediated method
Partical bombardment method
PEG-method
Electroporation method
Progress in salinity researchSaline Sodic Zn-def Acid
Donor Screening technique
Mechanism Genetics ? MAS development
Elite lines ?
= completed, = fast track, = not available /available /on-going
Lab.
Field
Salt tolerant rice varieties developed by IRRI and released in Philippines
IRRI 112 - PSBRc48 (Hagonoy) IRRI 113 - PSBRc50 (Bicol) IRRI 124 - PSBRc84 (Sipocot) IRRI 125 - PSBRc86 (Matnog) IRRI 126 - PSBRc88 (Naga) IRRI 128 - NSICRc106
Other salt-tolerant rice varieties
CSR10, CSR13, CSR23, CSR27, CSR30, CSR36 and Lunishree, Vytilla 1, Vytilla 2, Vytilla 3, Vytilla 4, Panvel 1, Panvel 2, Sumati, Usar dhan 1, 2 & 3 (India); BRRI dhan-40, BRRI dhan-41 (Bangladesh); OM2717, OM2517, OM3242 (Vietnam)
• Salt tolerance in rice is polygenic • Genes for salt tolerence have been
identified by molecular analysis• Molecular breeding strategies utilizing
these genes have been initiated to develop transgenic salt tolerant rice varieties.
Conclusion
Thank you all for your Kind attention