A male sterility system with a novel bifunctional selection strategy for hybrid seed production in maize

Seed production technology (SPT), initially developed by DuPont Pioneer, provides a novel recessive genetic male sterility system for maize hybrid seed production. It is critical for this technology to safeguard the purity of male sterile seeds from contamination by transgenic maintainer seeds. Here, we report a modified seed production technology (mSPT), which utilizes nicosulfuron as a de-selection agent in addition to mechanical sorting based on the fluorescence of maintainer seeds to achieve close to 100% purity of male sterile plants for hybrid seed production. The maintainer line MAR46 for mSPT showed very low transgene transmission rates in multiple inbred backgrounds. Out of the 10 inbred lines, 7 of them were found to have non-transmission. The highest transmission rate was 0.035% for one inbred line. Importantly, the maintainer plants were found to be sensitive to nicosulfuron in different inbred backgrounds. Thus, the extra built-in decontamination technology in the mSPT system reported here was able to further safeguard the purity of sterile male plants by a convenient nicosulfuron spray to kill possible contaminated fertile transgenic maintainer plants.