ABSTRACT The utilization of heterosis requires a sufficient amount of male‐sterile lines. Seed production technology (SPT) enables the production of large quantities of male‐sterile seed, thereby facilitating commercial scale hybrid seed production. This technology is implemented by introducing a transgenic cassette into a recessive genic male‐sterile mutant consisting of three modules: (1) a fertility restoration gene to restore the fertility of the male‐sterile mutant; (2) a pollen‐inactivation system expressing an amylase gene to inactivate the transgenic pollen grains; and (3) a seed marker system using red fluorescent protein (RFP) to distinguish transgenic from nontransgenic seeds. Previous studies have reported that a pollen‐inactivation system consisting of the PG47 promoter, BT1 signal peptide and ZM‐AA1 amylase gene can effectively prevent starch accumulation in pollen grains, thereby impairing pollen fertility. Up to date, most pollen‐inactivation systems still rely on the PG47 ‐ BT1 ‐ ZM‐AA1 module, which raises an intellectual property issue. This study aims to develop a new pollen‐inactivation system for rice SPT by joining the OsLSP3 promoter ( OsLSP3 pro ), ASP1 signal peptide and OsAA1 amylase gene together. We found that this novel system can effectively eliminate starch accumulation in pollen grains. Moreover, when replacing the pollen‐inactivation module in the rice SPT system, it can fully meet operational requirements. The new pollen‐inactivation system expands the toolbox for engineering male sterility systems in rice and holds significant promise for hybrid rice breeding and production.
Peng et al. (Mon,) studied this question.