Development of the male and female gametophyte, fertilization, and assessment of germination and regulation of dormancy in Iris aphylla L. seeds

The observations of fruiting and formation of offspring through generative propagation presented in this study were aimed at determination of propagation potential in Iris aphylla L. The low percentage of germinating seeds largely limits its generative reproduction. The germination tests confirmed deep dormancy of the Iris aphylla seeds. The dormancy was disrupted by isolation of embryos from seeds, which were further cultivated in vitro. The germination of isolated embryos proved the localization of endogenous inhibitors of germinating seeds of I. aphylla in the endosperm. The comparison of phytohormonal profiles of seeds, endosperm and embryos of I. aphylla and Iris sibirica, i.e. a species with a high percentage of germinating seed, revealed that the deep dormancy of I. aphylla seeds was associated with the balance between abscisic acid and gibberellins (ABA/GA), a significant predominance of ABA and a massive accumulation of salicylic acid. Isolation of embryos from seeds and their germination in growing medium in vitro is recommended as the most efficient method for I. aphylla propagation. Results of this study can be applied in conservation efforts of this attractive and important native species.