Abstract: Seed is the main reproductive form of seed plants. The appearance of seeds enables plants to have high tolerance to various environments during the seedling stage. Furthermore, seeds can be easily spread in various forms, which is one of the important factors accounting for the dominance of seed plants in nature. Most seeds contain essential nutrients for the next generation, making them a good food source consumed by seed predators. In this review, we classified seed defense strategies into three main types including direct, indirect, and space-time defense, and other complex forms. Some hot questions in the research area of adaptive strategies of seed defense are briefly mentioned. We propose that future studies of the evolution and maintenance of seed defense strategies would provide a more general understanding of seed defense in diverse plant species.

Key words: seed, seed predator, defense strategy, induced seed defense, evolution, plant-herbivore interaction.