Cubio tuber (Tropaeolum tuberosum, Tropaeolaceae) morphological diversity in Colombia and Bolivia

Tropaeolum tuberosum, commonly known as cubio, mashua, or isaño, is an underutilized crop belonging to the group of Andean tubers. Cubios harbor ample genetic and morphological variability, with tubers exhibiting the most variation. Morphological characterization is a fundamental approach for assessing cubio genetic diversity and is the crucial first step in germplasm classification. It is also a determinant for in-situ conservation practices carried out by farmers. Therefore, this study aimed to explore the morphological diversity of 15 cubio tuber accessions from Colombia and Bolivia, and to validate the findings by comparing them with previously published accessions. Based on tuber morphological descriptors, we calculated the diversity index and conducted PCA and clustering analyses on two datasets, consisting of (i) Colombian and Bolivian morphotypes and (ii) the latter plus previously published cubio data. Similarities were found in both the morphological diversity index and morphotype clustering between datasets, reinforcing the validity of the proposed morphological traits despite the limited sample sizes and inherent subjectivity in characterization. All accessions were successfully classified as distinct morphotypes, underscoring the considerable morphological variation present in cubios. This morphological variation reflects the wide underlying genetic variability in this species and highlights its adaptability to changing environmental conditions.