Backcross_Method_and_Male_Sterile_Line.pptx

Backcross_Method_and_Male_Sterile_Line

1. Backcross Method and Development of Male Sterile Line With Recessive Gene for Male Sterility Presented by: Aaditya Devadiga Course: Plant Breeding and Genetics Institute: NMIMS School of Agricultural Sciences and Technology

2. Introduction • Backcross method is a technique used to transfer a desired trait from a donor to a recurrent parent. • Helps improve a single trait while maintaining elite characteristics. • Important for developing male sterile lines.

3. Objectives of Backcross Breeding 1. Transfer a specific desirable gene. 2. Develop near-isogenic lines. 3. Improve a single trait without losing original traits. 4. Used in male sterility or fertility restoration breeding.

4. Terminology • Recurrent Parent (RP): Elite variety used repeatedly. • Donor Parent (DP): Source of desired gene. • F₁: Hybrid between RP and DP. • BC₁, BC₂, ...: Successive backcrosses. • Male sterility: Inability to produce viable pollen.

5. Steps in Backcross Method 1. Initial cross: RP × DP → F₁ 2. Backcross: F₁ × RP → BC₁ 3. Select plants with desired trait. 4. Repeat backcrossing for 5–6 generations. 5. Self and screen to fix recessive gene.

6. Development of Male Sterile Line (Recessive Gene) • Male sterility controlled by recessive gene (msms). • Fertile genotypes: MsMs or Msms • Sterile genotype: msms

7. Steps to Develop Male Sterile Line 1. Identify donor parent (msms). 2. Cross RP (MsMs) × DP (msms) → F₁ (Msms, fertile). 3. Backcross F₁ × RP → BC₁. 4. Select Msms (fertile) for next backcross. 5. After 5–6 backcrosses, self BC₆F₁. 6. Select msms (male sterile) → sterile line developed.

8. Example Crop: Sorghum or Pearl Millet Recessive gene: ms for male sterility Developed through repeated backcrossing with elite RP. Result: Male sterile line identical to RP except fertility trait.

9. Advantages ✓ Simple and effective for single-gene transfer. ✓ Recovers ~99% recurrent parent genotype. ✓ Suitable for recessive traits. ✓ Produces near-isogenic lines for hybrid breeding.

10. Limitations ✗ Time-consuming (many generations). ✗ Ineffective for polygenic traits. ✗ Recessive traits require selfing for expression. ✗ Linkage drag possible.

11. Applications 🌾 Transfer of disease resistance. 🌾 Incorporation of male sterility. 🌾 Development of restorer lines. 🌾 Improvement of agronomic traits.

12. Summary • Backcross method helps transfer recessive male sterility genes. • Involves repeated crossing with recurrent parent. • msms plants retain RP traits but are sterile. • Key for hybrid seed production programs.

13. References 1. Allard, R.W. (1960). Principles of Plant Breeding. Wiley. 2. Singh, B.D. (2015). Plant Breeding: Principles and Methods. Kalyani Publishers. 3. Acquaah, G. (2012). Principles of Plant Genetics and Breeding. Wiley-Blackwell.