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Genetic manipulation of stay-green traits for croop imporvement
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Genetic manipulation of stay-green traits for croop imporvement

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  • 1. Genetic manipulation of stay- green traits for crop improvement Shantanu Das Regn.no. : 11-AMJ-65Dept. of Plant breeding and Genetics
  • 2. ContentsIntroduction.Strategy for development of genotype withstay green traits.Physiological basis of stay-green traits.Importance of stay green traits.Genetic manipulation of stay-green traits.Case study on stay-green QTL introgression.Ideotype of stay-green genotype.The relationship between stay-green traits and grain yield.Conclusion.
  • 3. What is stay-green ? The extended foliar greenness during grain filling under post anthesis drought. Stay green is one such trait, and genotypes possessing this trait maintain more photosynthetically active leaves than genotypes not possessing this trait . Genotype with stay green traits is called stay green genotype.
  • 4. Where, When and Why stay green traits is required? It’s required specially in a drought environmental condition. To keep greenness of leaves alive for longer period of time, specially during the grain filling stage. To maintain or increase higher grain yield. Stay-green results when the plant’s normal process of senescence is disrupted.
  • 5. Strategy for development of genotype with stay green traits.Keeping alive for longer is the fundamental strategy for increase Crop yield Market value
  • 6. Components of stay green traits. Key components determining stay green: Total plant leaf area (TPLA): (+ve) correlated with green leaf area at maturity (GLAM) . Duration of leaf senescence: (+ve) correlated with GLAM. Rate of leaf senescence (LS): (-ve) correlated with GLAM NB: GLAM is an indicator of stay-green.
  • 7. Classes of stay green There is a five way of stay green on the basis of time and duration of occurrence of senescence. Type A stay greens (delayed initiation of yellowing) Type B stay greens (initiate senescence on schedule, but comparatively slow) Type C stay greens (arise due to specific defects in chlorophyll degradation pathway.) Type D stay greens (cell are dead) Type E stay greens ( chlorophyll content is remain same but enzyme activity is reduce)
  • 8. Five ways to stay‐green.
  • 9. Importance of chlorophyll in stay green traits. Chlorophyll pigment is responsible for greenness of the leaves. Chlorophyll pigment involved in photosynthesis. The result of photosynthesis is biomass production. When there wii be degradation, during the reproductive stage , ultimate biomass production will be less. Chlorophyllase (CLH) is responsible for degradation of chlorophyll a to chlorophyllide a (Chlide a) When a mutants disrupt the activity of chlorophyllase (CLH), it leading to stay-green phenotypes.
  • 10. Chlorophyll degradation initiation ×
  • 11. Relation of N2 with stay green traits Chemical structure of chlorophyll Chlorophyll pigment is consist of N2, Mg+2 and others constituent. Stay-green can be viewed as a consequence of the balance between N demand by the grain and N supply during grain filling stage. While N2 is the constituent of most of the proteins (Rubisco involved in photosynthesis).)
  • 12. 1. Importance of stay green traits in agronomical crops. Delayed senescence is useful only when it contributes to increase yield. N uptake during grain filling is higher in stay-green genotype than senescent hybrids. (Borrell and Hammer, 2000). In some crop it leads to drought resistance. It leads to lodging resistance.
  • 13. 2. Importance of stay green traits in horticultural crops. In horticultural crop it increases market value. Several approaches have been utilized to manipulate hormone level or responses in transgenic plants to reduce the incidence of postharvest yellowing. It extends shelf-life and helps in long term transportation.
  • 14. Genetic manipulation of stay green traits
  • 15. A. Identification of QTL for stay green.Requirement for QTL mapping:1. A suitable mapping population generated from phenotypically contrasting parents.2. Reliable Phenotypic screening of mapping population.3. A saturated linkage map based on molecular markers.4.Appropriate statistical packages to analyze the genotypic information in combination with phenotypic information for QTL detection.
  • 16. 1. and 2. Phenotypic screening of mapping population. P1 x P2 Recipient Donor F1 F2 F2:F3 Phenotypic screening Trials plot Screening is going on
  • 17. (1) LEAF TISSUE SAMPLING (2) DNA EXTRACTION (3) PCR(4) GEL ELECTROPHORESIS (5) MARKER ANALYSIS
  • 18. Stay-green QTL have been identified – Few to mention Crop Identified QTL ReferenceEnglish blue Recessive nucleargrass (Festuca allele sid Thomas(1997)Pratensis ) Stg1, Stg2, Stg3, andSorghum Stg4. Wenwei Xu et al. (2000) recessive gene fiwArabidopsis maped on chromosome Nakamura et al. 4 ( 2000)
  • 19. Stay-green QTL have been identified – Few to mention Crop Identified QTL Reference Recessive mutant geneRice sgr(t) on Cha et al. (2002) chromosome 9 46 main QTL for six Jiang et al. (2003)Rice trait are localized in 25 chromosomal regionWheat QSg.bhu-1A, QSg.bhu-3B Uttam Kumar et(Triticum and QSg.bhu-7D al. (2010)aestivum L.)
  • 20. Marker assisted breeding P1 x P2Susceptible Resistant F1 F2 MARKER-ASSISTED SELECTION (MAS)
  • 21. Marker assisted breeding P1 x P2Susceptible Resistant F1 F2
  • 22. Marker assisted backcrossing
  • 23. Marker-assisted backcrossing (MAB) There are three levels of selection in which markers may be applied in backcross breeding. 1 2 3 4 1 2 3 4 1 2 3 4 Target locus FORGROUND RECOMBINANT BACKGROUND SELECTION SELECTION SELECTION Foreground selection : to screen for the target trait. Recombinant selection: to minimize linkage drag. Background selection: to the recovery of the recurrent parent genome.
  • 24. CASE STUDYINTROGRESSION OF STAY-GREENTRAITS INTO A KENYAN FARMER PREFERED SORGHUM VARIETY K. NGUGI, W. KIMANI1 and D. KIAMBI1
  • 25.  A MAB breeding programme was conducted tointrogress stay green QTL from ICRISAT sorghum lineE36-1 well-characterised for stay-green QTL, into thebackground of the Kenyan farmers’ preferredsorghum variety, Ochuti.  E36-1 donor parental line  Ochuti recurrent parental line The parental lines E36-1 has 3 stay green QTLs, SBI-01, SBI-07 and SBI-10 located at various chromosomes.
  • 26. Make the backcross and to select the genotypes with Stay-green QTL E36-1 Ochuti Donor parent Recurrent parent X Collection of leaves at 15 Collection of leaves at days after sowing 15 days after sowing for genotypingfor genotyping ` Ochuti F1 X Collection of leaves from 96 F1 progenies BC1F1 Leaves collection from 128 individual for genotyping for identifying genotype with the Stay-green QTL
  • 27. Contd. Seven forground marker were used to identify individuals of F1 generation that had stay green QTLs transferred into Ochuti. Out of 96 F1 genotype only five genotypes that had at least one stay green QTL introgressed, 3 with two QTL ( SBI-07 and SBI-10) and 2 other F1 genotypes had only one QTL (SBI-10) transferred into Ochuti. A total of 128 BC1F1 DNA samples together with the two positive controls (the two parents) were genotyped with the five foreground SSR markers.
  • 28. Ideotype of genotype with stay green traits Plant should have spread and deep root system. Genotype with stay green traits should show slow rate of leaf senescence(LS). Delay onset of leaf senescence(LS). Genotype should have more total plant leaf area (TPLA).
  • 29. The relation between the stay green traits and grain yield Grain yield was correlated positively with green leaf area at maturity and negatively with rate of leaf senescence (from the study of nine genotypes varying in stay-green, Borrell et al.,1999). GLAM ⍺ Grain yield Rate of leaf senescence ⍺
  • 30. CONCLUSION Several stay-green QTL have been identify in Several crops like sorghum, wheat, rice etc. By hybridization programme, its is enable to transfer identified stay-green QTL to the genotype having good agronomic background. Incorporation of stay-green trait in a genotype will increase the ultimate grain yield and market value which will contribute to our national economy.

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