Stress influences seed germination in mucilage-producing chia

Chia (Salvia hispanica L.) is an oil seed crop, with a high ω-3 fatty acid and fiber content, used for food and medicine. Upon imbibition, seeds (nutlets) exude a pectinaceous mucilage. The impact of mucilage on seed germination under different environments is unknown. The objectives of this study were to investigate the potential impact of mucilage on chia seeds germinated under conditions of biotic and abiotic stress. Chia seeds were germinated with or without mucilage under various stress conditions in lab and greenhouse studies. Germination conditions included exposure to water, cold, heat, salt stress, and fungal infection. The mucilage was removed following hydration with an acid wash without impacting germination. There was no difference in final germination percentage of seeds with or without mucilage under optimal lab conditions. However, seeds with mucilage removed germinated more slowly, with 63% germination after 26 h compared with 97% in seeds producing mucilage. Seed germination on polyethylene glycol solutions with increasingly negative water potentials was reduced in seeds without mucilage. Seeds with mucilage production that were exposed to cycles of wetting and drying germinated better and faster than non-mucilage-containing seeds. Greenhouse emergence showed a similar trend, with mucilage-producing seeds having greater emergence at lower substrate moisture levels. Under saline conditions, mucilage-producing seeds germinated 48% higher than non-muci-lage-producing seeds at 200 mM NaCl. The data suggest that seed mucilage production may impart an ecological advantage in arid or semiarid habitats with irregular soil moisture or soils with high salt levels.