Research progress and prospects of two-line hybrid wheat in China

Abstract

<p indent="0mm">The effective utilization of wheat heterosis has been a worldwide problem. Since the 1950s, systematic research has mainly focused on the “three-line method” and “chemical killing method” of obtaining hybrid wheat and has not made substantial progress into the present. In the 1990s, two-line hybrid wheat technology created by Chinese scientists based on the discovery and utilization of wheat with photo-thermal-sensitive male sterile germplasm has developed rapidly, making China the only country that uses sterile lines for commercial hybrid wheat production. From the perspective of the whole agroindustrial chain, the research advances of two-line hybrid wheat in China were analyzed and summarized, including germplasm discovery, light-temperature conversion characteristics, genetic mechanisms of wheat photo-thermo-sensitive male sterile lines, selection of male sterile lines, creation of restorer lines, innovation of strong heterotic hybrids, technology for large-scale seed production, and various demonstrations and extensions. The genetic diversity of the photo-thermal-sensitive male sterile lines was examined, and the transformation regulation model of photo-thermo-sensitive male sterility in wheat was thus revealed, indicating that different types of male sterile lines have different restorer genes. The creation of restorer lines through multi restorer gene polymerization and implementing spring × winter wheat hybridization have been illustrated as effective ways to create strongly heterotic hybrids. Taking advantage of hybrid vigor in terms of the ecological synergy, physiological synergy, and temporal and spatial synergy between the parental lines, the invention of the mixed sowing seed production methods, and whole-process mechanization, the seed production yield of two-line hybrid wheat has been greatly improved. Thus, the associated seed production cost has been reduced, laying a critical foundation for the industrial production of hybrid wheat. Here, suggestions and prospects for technological innovation and industrialization of two-line hybrid wheat in China are also described, and it is noted that geographically, ecologically, and genetically distant germplasm should be further utilized to cultivate hybrid wheat varieties with strong advantages. Strengthening the creation of sterile lines and restorer lines with high outcrossing rates, high resilience, and high combining ability and greatly improving the yield of seed production are the keys to future research and development of hybrid wheat. It is clear that this is an important period of opportunity for the research and application of China’s hybrid wheat to achieve leapfrog development. It is of great strategic importance for China to maintain its international leading position in hybrid wheat development and production as well as seize the commanding heights of the international seed industry of hybrid wheat and ensure national food security.