Backcross_Method_and_Male_Sterile_Line (1).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, Krushna Rajput, Prasanna Salunkhe

2. Introduction A cross between F1 hybrid and one of its parents is known as a backcross It is used to transfer a desired trait from a donor to a recurrent parent. Helps improve a single trait while maintaining elite characteristics. It was proposed by Harlan and Pope in 1922

3. Applications of Backcross Method Intervarietal transfer of simply inherit characters such as disease resistance, seed colour, plant height etc. Intervarietal transfer or quantitative characters (earliness, seed size, seed shape) may be transferred from one variety to other of same species. Interspecific transfer of simply inherited characters i.e. disease resistance from related species to cultivated species Production of isogenic line.

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

6. Advantages The genotype of new variety is nearly identical with that of the recurrent parents. It is not necessary to test the variety developed by this method. Does not depend upon environment. It is useful for developing disease resistance var generally interspecific gene transfer. It is rapid, predicted and repeatable. It is useful for removing some defects such as abnormality, disease resistant etc.

7. Development of Male Sterile Line (Recessive Gene)

8. Male sterility controlled by recessive gene ( msms ). Fertile genotypes: MsMs or Msms Sterile genotype: msms

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

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