Development of accessible and scalable maize pollen storage technology.

The inherent short lifespan of Zea mays (maize, corn) pollen hinders crop improvement and challenges the hybrid seed production required to produce food, fuel, and feed. Decades of scientific effort on maize pollen storage technology have been unable to deliver a widely accessible protocol that works for liters of pollen at a hybrid seed production scale. Here we show how suppressing the pollen cellular respiration rate through refrigeration and optimizing gas exchange within the storage environment are the critical combination of factors for maintaining pollen viability in storage. The common practice of preserving maize pollen by mixing the pollen with talcum powder is critically examined using pollen tube germination testing, electron microscopy of pollen-silk (stigma) interaction, and test pollinations in production environments. These techniques lead to mixing maize pollen collected for storage with anti-clumping carrier compounds, including microcrystalline cellulose. These carriers improve stored pollen flowability during pollination and enable increased seed sets to be obtained from stored pollen. Field testing in maize seed production demonstrates that a wide range of pollen volumes can be stored for up to seven days using low-cost, globally available materials and that stored pollen can achieve seed-set equivalency to fresh pollen.