Abstract:

Background & AimThe floral spur stands out as a key innovative trait that has evolved in response to the interaction between plants and pollinators. This trait is widely distributed in angiosperms, showcasing a highly variable morphology among different species. Previous research has focused on exploring the complex relationship between floral spur and their corresponding pollinators.

ProgressFirstly, this review introduces the concept and function of the spur, elucidating the diversity in spur morphology, length, color, and contents of across various species; secondly, it describes the factors contributing to intraspecific and interspecific variations in floral spur morphology; then, it summarizes a series information on cellular and key molecular mechanisms governing the formation and development of floral spur. The distribution of the spur in angiosperms, coupled with the diversity in spur formation sites and the molecular mechanisms of development, suggests that the multiple origins of the spur with convergent evolutionary features, but the pattern of floral spur formation and development appears non-conserved in the evolutionary progression.

Prospects This review offers the following perspectives for future research on floral spur: (1) Constructing a comprehensive database documenting the phenotypes of angiosperm floral spurs to provide fundamental data for the systematic investigations; (2) Constructing a mutant library of floral spur through genetic engineering and other tools to further verify the contribution of floral spur variants to species diversity; (3) Investigating the molecular mechanisms of the formation and development of floral spur using a multi-omics approach.

Key words: floral spur, key innovation, pollination, floral spur development, molecular mechanisms