Development of accessible and scalable maize pollen storage technology

Pollination is a critical step in the life cycle of agricultural crops and is required to form the seed, grains, and fruits that humans rely on for food and feed products. Pollen longevity is diverse across crop plant species, with some agricultural fruit trees producing pollen that can survive for years ¹ , while the pollen of Oryza sativa (rice) remains viable for as little as four minutes in the open air ² . Zea mays (maize, corn) has been subject to decades of scientific plant breeding and the value of pollen storage has been recognized for over 100 years ³ , yet the inherent short lifespan of maize pollen still hinders germplasm improvement and hybrid seed production. Here we show that suppressing respiration rate and optimizing storage environment gas exchange are the critical combination of factors for maintaining pollen viability in storage. Pollen tube germination testing and electron microscopy of pollen-silk (stigma) interaction led to the discovery of novel anti-clumping agents including microcrystalline cellulose that improved pollen flowability and increased seed set post-storage. Field testing in maize seed production demonstrated that a wide range of pollen volumes can be stored for seven days using low-cost, globally available materials and can achieve seed-set equivalency to fresh pollen. We anticipate that the pollen storage protocol which resulted from these breakthroughs will be a valuable tool for plant breeders working towards the continued genetic improvement of maize. Further scale up of the technology will provide a means to mitigate pollination challenges common to maize hybrid seed production for the greater benefit of farmers and consumers.