Review and prospect on utilization of heterosis between <italic>indica</italic>-<italic>japonica</italic> rice subspecies

Abstract

The utilization of heterosis between indica-japonica rice subspecies is important for the improvement of rice yield in China. This paper reviewed the historical development of the utilization of heterosis between indica-japonica rice subspecies. Since the discovery of wide compatibility gene in 1982, it has laid a theoretical foundation for the breeding of inter subspecies hybrid rice. In 1980s scientific research institutions bred the part of utilization of heterosis between indica-japonica hybrid rice combinations, Liangyoupeijiu and Xieyou 9308, which the heterosis was high. In 21st century, many scientific research institutions in Zhejiang Province bred the tipical indica-japonica hybrid rice combinations, Yongyou 6, Yongyou 12, Chunyou 58 and Chunyou 84, by breeding the japonica CMS lines and the indica-japonica wide compatibility restorer lines, which the heterosis was more obvious. They opened a new way for the using of heterosis between indica-japonica . This paper summarized the present situation of utilization of heterosis between indica-japonica from two aspects of basic theory research and research progress of utilization of heterosis between indica-japonica , and looked forward for the future utilization of heterosis between indica-japonica rice subspecies on the main problems existing in the utilization, and presented the solutions such as expandding the genetic relationship to enhance the heterosis, optimizing parental characteristics to enhance the yield of hybrid seed production, using the modern technology to improve the breeding efficiency, in order to provide a useful reference for the research on the utilization of heterosis between indica-japonica rice subspecies. According to the components of parents or the genetic distance between indica-japonica , we divided the hybrid between indica-japonica heterosis utilization into three stages: the part of utilization of heterosis between indica-japonica , the typical utilization of heterosis between indica-japonica and the complete utilization of heterosis between indica-japonica . We can believe that in the near future, the free combination of indica-japonica rice subspecies will be realized and the heterosis between indica-japonica rice subspecies can be completely used through the continuous efforts of breeders.