AUTHOR=Zhang Guiquan 

TITLE=The Next Generation of Rice: Inter-Subspecific Indica-Japonica Hybrid Rice

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.857896

DOI=10.3389/fpls.2022.857896

ISSN=1664-462X

ABSTRACT=<p>Rice (<italic>Oryza sativa</italic>) is an important food crop and has two subspecies, <italic>indica</italic> and <italic>japonica</italic>. Since the last century, four generations of rice varieties have been applied to rice production. Semi-dwarf rice, intra-subspecific hybrid rice, and inter-subspecific introgression rice were developed successively by genetic modification based on the first generation of tall rice. Each generation of rice has greater yield potential than the previous generation. Due to the stronger heterosis of <italic>indica</italic>-<italic>japonica</italic> hybrids, utilization of the inter-subspecific heterosis has long been of interest. However, <italic>indica</italic>-<italic>japonica</italic> hybrid sterility hinders the utilization of heterosis. In the past decades, <italic>indica</italic>-<italic>japonica</italic> hybrid sterility has been well understood. It is found that <italic>indica</italic>-<italic>japonica</italic> hybrid sterility is mainly controlled by six loci, <italic>S5</italic>, <italic>Sa</italic>, <italic>Sb</italic>, <italic>Sc</italic>, <italic>Sd</italic>, and <italic>Se</italic>. The <italic>indica</italic>-<italic>japonica</italic> hybrid sterility can be overcome by developing <italic>indica</italic>-compatible <italic>japonica</italic> lines (ICJLs) or wide-compatible <italic>indica</italic> lines (WCILs) using genes at the loci. With the understanding of the genetic and molecular basis of <italic>indica</italic>-<italic>japonica</italic> hybrid sterility and the development of molecular breeding technology, the development of <italic>indica</italic>-<italic>japonica</italic> hybrid rice has become possible. Recently, great progress has been made in breeding <italic>indica</italic>-<italic>japonica</italic> hybrid rice. Therefore, the <italic>indica</italic>-<italic>japonica</italic> hybrid rice will be the next generation of rice. It is expected that the <italic>indica</italic>-<italic>japonica</italic> hybrid rice will be widely applied in rice production in the near future.</p>