Breeding of Vegetable, Spice and Tuber crops (2+1)

Backcross-Dominant gene transfer

How Dominant Gene is transferred through Backcross Breeding?

• Let the variety X is well adapted and high yielding.
• Variety Y is resistant to a specific disease; which is governed by a dominant gene. We wish to transfer this dominant gene form variety Y to variety X.
• So, variety X – recurrent parent (♀) Variety Y – donor parent (♂)
• The various steps in backcrossing are as follows

 
• Hybridization – The two varieties X and Y are crossed. Generally recipient / recurrent variety is used as female parent.
• F1 generation – Selection for disease resistance is not performed. Plants from F1 seed are back crossed with recipient variety X and seeds are collected to raise BC1 generation.
• First backcross generation (BC1) – Selection is done for disease resistance and selected ones are back crossed with recurrent parent X.
• Second to fifth backcross generation (BC2 to BC5) – Segregation for disease resistance occurs in every back cross generation. Plants are selected on the basis of similarity with recurrent parent and resistance to disease. Selected ones are back crossed with recurrent parent X.
• Sixth backcross generation (BC6) – Disease resistant plants are selected. They are self pollinated and harvested separately.
• BC6 F2 generation – Individual plant progenies are grown from seeds of BC6 generation. Plants are selected on the basis of similarity with recurrent parent and at the same time resistance to disease. They are harvested separately.
• BC6 F3 generation – Individual plant progenies are grown from seeds of above cross. As done in above step, plants are selected on the basis of similarity with recurrent parent and resistance to disease but harvested in bulk.
• Yield trials – Replicated yield trials are conducted with recurrent parent as a check. The newly constituted variety should be similar to variety X for most of the important characteristics with resistant to disease. Seeds are multiplied for distribution.