Exploring floral morphology and scent profile of Gladiolus murielae: a wild crop relative for fragrance introgression

Abstract

Gladiolus is a commercially significant bulbous ornamental crop with numerous varieties showcasing a wide range of colours and forms, yet it lacks fragrance. It is commonly used as cut flower, for garden display and as potted plant. The fragrant species of gladiolus originally Gladiolus murielae is valued for its scented star shaped flowers. However, the complexity of fragrance in this species is highly unexplored. The study emphasizes the floral morphological characterization and fragrance profiling of G. murielae, aiming to establish its breeding behavior to utilize in the development of fragrant gladiolus cultivars. Morphological characterization revealed that the plants have grassy foliage, and the flowers are white in color with a maroon blotch on the throat with good multiplication efficiency. Anthesis and anther dehiscence occur in the morning, anther dehisces with longitudinal slit, and the trifid stigma unfurls upon receptivity. The pollen grains are viable, monad, with a paraisopolar orientation, and featured the microreticulate exine, and are suitable as pollen parents. Comparative fragrance profiling at three different flower opening stages (bud, half open and full open) recognized the presence of 55 volatile organic compounds (VOCs) throughout the floral lifespan. Clustering through heat map divided the 55 VOCs into four clusters indicating the prevalence of volatile diversity. Cineole peaked at half bloom, cis-Sabinene hydrate and methyl salicylate were abundant in bud stage, and methyl benzoate appeared exclusively at full bloom. Results of the PCA specified that the first two components contributed for 84 % of the total fragrance variation. This study identifies the major VOCs that are responsible for fragrance and facilitates further studies like identification of underlying genes and the introgression of those fragrant genes into desirable backgrounds, leading to the development of scented gladiolus varieties.