Domestication Reduces Floral Volatile Richness in Squash (Cucurbitaceae: Cucurbita) But Conserves Key Compounds...

Area of Science:

• Plant Biology
• Chemical Ecology
• Evolutionary Biology

Background:

• Domestication significantly alters plant phenotypes, but its impact on floral traits crucial for plant-pollinator interactions is not well understood.
• Floral volatile organic compounds (VOCs) are vital signals for attracting pollinators and indicating resource availability.

Purpose of the Study:

• To investigate how domestication influences floral VOC composition in the genus Cucurbita.
• To assess the response of the squash specialist pollinator, Xenoglossa pruinosa, to floral VOCs from wild and domesticated squash species.

Main Methods:

• Characterization of VOC profiles in wild and domesticated Cucurbita species.
• Combined gas chromatography-electroantennography (GC-EAG) to identify electrophysiologically active VOCs.
• Field assays using blue vane traps and pollinator visitation experiments to evaluate bee responses to specific VOCs and blends.

Main Results:

• Domesticated squash species exhibited significant losses in their VOC blends compared to wild relatives.
• Ten electrophysiologically active VOCs were identified, with 1,4-dimethoxybenzene found to be a potent attractant for bees in isolation.
• Bee visitation was associated with increased emissions of 1,4-dimethoxybenzene, dihydro-β-ionone, and (E)-nerolidol, and decreased emissions of linalool and methyl salicylate.

Conclusions:

• Domestication reshapes plant-pollinator communication by altering floral volatile emissions.
• Specific VOCs, like 1,4-dimethoxybenzene, can act as key attractants for pollinators, even when present in reduced blends.
• Understanding these chemical ecology shifts is crucial for managing crop-pollinator interactions in agricultural systems.