DUS-MAS: A Modified Marker-Assisted Backcross Breeding (MABB) Method for Higher Background Genome and DUS Trait Recovery

Abstract

Backcross breeding is used to transfer an desirable trait from donor to recurrent parent (RP), and it takes six to seven generations for 99% recovery of the recurrent parent genome (RPG). Marker-assisted backcross breeding (MABB) was proposed to accelerate the recovery of the RPG. Over the period of time, MABB has evolved as per the available resources and time frame. One of the major modifications is the number of foreground-selected individuals which are subjected to background selection. This number varied widely and lacked consensus in different studies. Further, the major drawback of the existing method is that the DUS traits are recorded directly in the improved lines. Once the traits are fixed in the finished product, there is no going back to bring the corresponding traits of RP. The modified MABB method (DUS-MAS) can ensure higher recovery of DUS traits and RPG. A yield index has also been developed for the identification of high yielding individuals in backcross generation. In DUS-MAS, the foreground-positive individuals are selected first, and then individuals with a higher yield index are selected. Thereafter, the foreground and yield index positive individuals are selected for higher recovery of DUS traits. Five such individuals are subjected to marker-based background recovery of which only two with the highest recovery were advanced to the next generation. All these steps are to be followed in BC₁F₁, BC₂F₁, and BC₂F₂ generations. It substantially reduces the cost by reducing the use of laboratory chemicals by more than 75%.