Selection based on markers
- 1. Selection Based On Marker SUBMITTED TO Dr. G.M. Lal GPB-731 Plant breeding Department SUBMITTED BY Muppala Tanuja
- 2. Introduction Marker assisted selection (MAS) refers to the use of DNA markers that are tightly-linked to target loci as a substitute for or to assist phenotypic screening or The use of genetic markers with the phenotypes in a process called Marker assisted selection.
- 6. Markers must be tightly-linked to target loci • Ideally markers should be <5 cM from a gene or QTL • Using a pair of flanking markers can greatly improve reliability but increases time and cost Marker A QTL 5 cM RELIABILITY FOR SELECTION Using marker A only: ~95% Marker A QTL Marker B 5 cM 5 cM Using markers A and B: ~99.5%
- 7. Markers must be polymorphic RM84 RM296 1 2 3 4 5 6 7 8 P1 P2 1 2 3 4 5 6 7 8 P1 P2 Not polymorphic Polymorphic!
- 8. General Steps in MAS 1.Selection of parents. 2.Development of Breeding Population. 3.Isolation of DNA. 4.Scoring RFLP. 5.Correlation with Morphological traits.
- 9. F2 F1 P1 P2 x large populations consisting of thousands of plants PHENOTYPIC SELECTION Field trials Glasshouse trials Donor Recipient CONVENTIONAL PLANT BREEDING Salinity screening in phytotron Bacterial blight screening Phosphorus deficiency plot
- 10. (1) LEAF TISSUE SAMPLING (2) DNA EXTRACTION (3) PCR (4) GEL ELECTROPHORESIS (5) MARKER ANALYSIS Overview of ‘marker genotyping’
- 11. F2 F1 P1 x P2 large populations consisting of thousands of plants Resistant Susceptible MARKER-ASSISTED SELECTION (MAS) MARKER-ASSISTED BREEDING Method whereby phenotypic selection is based on DNA markers
- 12. Marker-assisted backcrossing (MAB) Selection for target gene or QTL 1 2 3 4 1 2 3 4 1 2 3 4 Target locus TARGET LOCUS BACKGROUND SELECTION SELECTION FOREGROUND SELECTION BACKGROUND SELECTION Accelerates the recovery of the recurrent parent genome
- 13. CONVENTIONAL BACKCROSSING P1 x P2 P1 x F1 BC1 VISUAL SELECTION OF BC1 PLANTS THAT MOST CLOSELY RESEMBLE RECURRENT PARENT BC2 MARKER-ASSISTED BACKCROSSING P1 x P2 P1 x F1 BC1 USE ‘BACKGROUND’ MARKERS TO SELECT PLANTS THAT HAVE MOST RP MARKERS AND SMALLEST % OF DONOR GENOME BC2
- 14. Application of MAS 1.It is useful in gene pyramiding for disease and insect resistance. 2.Uses in backcrossing programme. 3.It is being used for transfer of male sterility into cultivated genotypes from different sources. 4.MAS is being used for improvement of quality characters in different crops such as for protein quality in maize, etc…
- 15. Advantage of MAS 1. Accuracy, 2. Rapid Method, 3. Non-transgenic Product, 4. Identification of Recessive Alleles, 5. Early Detection of Traits, 6. Screening of Difficult Traits, 7. Highly Reproducible, 8. Small Sample for Testing,etc…
- 16. Achievements of MAS 1. Rice- a.(PB1 x JRBB55)Improved Pusa Basmati 1, b.Improved Sambha Mahsuri(BPT5204), 2.Maize-Improved QPM-9, 3.Pearlmillet-HHB67-2, 4.Wheat-Patwin,etc