• Grape hyacinth exhibits aroma intensity variation between upper and lower flowers. • VOCs and their sensory attributes showed clear differentiation between floral parts. • Myrtenol and 1-octen-3-ol established characteristic grassy and oily base notes across species. • Three species developed distinct aromatic profiles through specific compounds. Functional differentiation between sterile and fertile flowers is a key plant adaptation. While research has focused on visual traits, less attention has been given to volatile organic compounds (VOCs). Grape hyacinth ( Muscari spp.), with its stable inflorescence pattern of fertile (open) lower and sterile (closed) upper flowers, is an ideal model for such study, yet its VOC composition remains uncharacterized. From ten initially screened species, three representative ones— M. azureum (M1), M. armeniacum ‘Heavenly Blue’ (M2), and M. aucheri ‘Ocean Magic’ (M3)—were selected based on highly significant differences in aroma intensity between upper and lower flowers. Analyses revealed spatial differentiation in VOCs and corresponding sensory attributes: upper flowers produced fewer compounds and were enriched in myrtenol and 1-octen-3-ol, potentially facilitating long-distance pollinator attraction, whereas lower flowers released more diverse VOCs that may prolong visitor retention. Myrtenol and 1-octen-3-ol established characteristic grassy and oily base notes across species. The three species developed distinct aromatic profiles through specific compounds: M1 accumulated ethyl phenylacetate with cocoa nuances; M2 contained abundant myrtenol and eucalyptol with minty tones; and M3 displayed fruity notes due to synergistic interaction between (Z)-β-ocimene and methyl salicylate. Furthermore, 1-octen-3-ol exhibited context-dependent expression, presenting earthy notes at Relative Odor Contribution (ROC) ≥ 99 % but shifting to herbaceous and oily tones at ROC < 50 %. In complex odor environments, myrtenol and acetophenone diverged from their typical minty and sweet-fruity profiles to instead contribute green nuances and modified minty characters. Additionally, sub-threshold ethyl phenylacetate helped shape the distinctive cocoa-fermented aroma in M1 through synergistic effects, further demonstrating how compound interactions dynamically modulate odor perception. This study demonstrates spatial differentiation of VOCs between upper and lower flowers in grape hyacinth and their potential ecological functions, providing new chemical insights into the evolution of floral traits and pollination strategies.
Lou et al. (Sat,) studied this question.