Vivipary in <i>Festuca glauca</i>: Analysis of Inflorescence Anatomy and Endogenous Hormones

Vivipary in plants evolved under long-term adaptation to harsh environments and is an important reproduction pathway. However, the mechanisms driving vegetative vivipary are still unclear. In this study, we investigated the anatomy of viviparous inflorescences of Festuca glauca ‘Elijah Blue’ using stereomicroscopy and paraffin section anatomical observation. We also determined the contents of endogenous hormones in normal and viviparous inflorescences using an enzyme-linked immunosorbent assay. In viviparous inflorescences, typical upper and lower epidermal tissues, spongy tissue, and palisade tissue of leaves appeared in developmental stages 2 and 3 (20 and 45 days after emergence), indicating vegetative vivipary, which was consistent with the stereomicroscope results. The contents of auxin, gibberellin, and abscisic acid in viviparous inflorescences increased from stage 1 to stage 4, with the content of abscisic acid showing a particularly large increase. At stage 2, the difference in abscisic acid content between viviparous and normal inflorescences was 95.2410 ng/g fresh weight (FW) (81.49% increase in content). These results indicate that high levels of abscisic acid promote vivipary. There were also significant differences (p < 0.05) in zeatin riboside and brassinosteroid between normal and viviparous inflorescences at each developmental stage. Our results lay a foundation for the preliminary exploration of the mechanisms driving vivipary in F. glauca. Further research on the genes and transcription factors involved in vivipary is still needed.