Innovation and development of the third-generation hybrid rice technology

The breeding and large-scale application of hybrid rice contribute significantly to the food supply worldwide. Currently, hybrid seed production uses cytoplasmic male sterile (CMS) lines or photoperiod/thermo-sensitive genic male sterile (PTGMS) lines as female parent. Despite huge successes, both systems have intrinsic problems. CMS systems are mainly restricted by the narrow restorer resources that make it difficult to breed superior hybrids, while PTGMS systems are limited by conditional sterility of the male sterile lines that makes the propagation of both PTGMS seeds and hybrid seeds vulnerable to unpredictable climate changes. Recessive nuclear male sterile (NMS) lines insensitive to environmental conditions are widely distributed and are ideal for hybrid rice breeding and production, but the lack of effective ways to propagate the pure NMS lines in a large scale renders it impossible to use them for hybrid rice production. The development of "the third-generation hybrid rice technology" enables efficient propagation of the pure NMS lines in commercial scale. This paper discusses the establishment of "the third-generation hybrid rice technology" and further innovations. This new technology breaks the limitations of CMS and PTGMS systems and will bring a big leap forward in hybrid rice production.