Correspondence Between Trichome Morphology and Phylogenetic Distance in Six Solanaceae Species

Abstract

Trichomes are highly diverse epidermal appendages, but their phylogenetic utility remains insufficiently tested in a quantitative framework. This study evaluated whether quantitative trichome morphology corresponds to molecular phylogenetic distance in six Solanaceae species. Twenty-six quantitative traits were measured from scanning electron micrographs, and a focal trait block composed of Tortuosity, Mean Curvature, and Curvature per Length was prioritized for analysis. Species-level morphological distances were calculated from standardized trait values and compared with patristic distances derived from an rbcL- and matK-based phylogeny using exact Mantel tests. The focal trait block showed significant positive correlation with molecular distance (Spearman  = 0.775, p = 0.044; Pearson  = 0.865, p = 0.046). Although principal component analysis did not produce complete visual separation among all species, the distance-matrix comparison showed concordant variation between trichome morphology and molecular phylogeny. Sensitivity analysis further showed that adding Contraction Ratio weakened the correspondence. These results indicate that the focal path-curvature trait block captures a limited but significant matrix-level phylogenetic signal in the six Solanaceae species examined, although a robust morphology-based classification system has not yet been established.