Development of salt tolerant IR64 near isogenic lines through marker-assisted breeding

Salt stress causes considerable damage to rice with a consequent reduction in grain yield, however, conventional breeding for this stress is time-consuming and costly. Recently, marker-assisted breeding has shown enormous potential to accelerate breeding of stress tolerant varieties because of its precision, time saving, and cost effectiveness. The present study was carried out to transfer Saltol, a major QTL on chromosome 1 associated with salinity tolerance, from FL478, a tolerant genotype, into IR64, a popular lowland variety through marker-assisted backcrossing (MABC). This technique considerably enhanced the recovery rate of the recurrent parent genome within three backcross generations, which could have saved several backcrosses compared with conventional schemes to achieve the same results. By using this technique, up to 99.7% of the recurrent parent genome was recovered at BC₃F₂ generation, saving at least three backcrosses compared with conventional breeding schemes. Salinity tolerance of IR64-Saltol lines was evaluated using saline culture solution adjusted to electrical conductivity of 12 dS m^-1 using NaCl. Based on selected physiological and growth parameters, the new Saltol introgression lines showed a significantly higher tolerance of salinity than their recurrent parent IR64. The results of this study confirm the benefits of using molecular markers in plant breeding to enhance tolerance of abiotic stresses.