Developing an Open-Ended Recurrent Selection Breeding Approach with Dominant Genic Male Sterile Rice

Dominant Genic Male Sterile rice（DGMS）provides an ideal vehicle for establishing multiple inter-cross population for recurrent selection. In this study, four typical japonica rice male sterile lines were test-crossed with six indica-japonica restorer lines, and five high-compatibility restorer lines were selected based on a seed setting rate above 85% in the F₁ hybrids. Using these high-compatibility restorer lines as recurrent parents, they were backcrossed with a dominant genic male sterile line to obtain a BC₃F₁ population, which segregated into fertile and sterile plants at an equal ratio in each generation. The fertile plants, after pedigree selection and screening for stress tolerance, could be incorporated as new germplasm into the donor male parent pool following test-crossing, representing a classical pathway of traditional recurrent selection. In contrast, the sterile plants could serve as a bridge to introduce new germplasm in each crossing round, thereby establishing an open-ended recurrent selection population. This method was applied to the breeding of high-compatibility restorer lines in rice, and 108 candidate lines from the F₃ to F₇ generations were obtained from this population. The advantages and disadvantages of open-ended recurrent selection versus traditional closed recurrent selection were also discussed.