Morfología de semillas de siete especies del género Opuntia (Cactaceae) del sureste de Coahuila (México)

Background and aims: Opuntia’s natural distribution encompasses from Canada to Argentina and it is part of the landscape in some regions of the world. There are between 191 and 215 Opuntia species. The ex situ conservation of this phytogenetic resource has gained relevance, but the species identification using the seeds is a limitation when there is a lack of reliable morphological traits. The purpose of this research work was to characterize the seed morphology of seven Opuntia species and identify their own morphological traits, in order to establish the species’ identification criteria when seeds are the only source of preserved plant material. M&M: We used the attrition and image analysis technique to measure: seed coat thickness (GT), ventral funicular coat thickness (GCFV), embryo’s length, embryo’s surface area, major axis length and minor axis length. The most outstanding traits were detected through exploratory ANDEVA and main components methods. The species classification and forecasting were based on a supervised multivariate analysis. Results: Differences in all the variables among species were significant. Opuntia ficus-indica had the largest seeds. GCFV and GT were the most helpful variables in terms of discrimination. The main component analysis explained 92% of the total variation. K- Nearest Neighbor method was able to forecast correctly 83% of the species classification cases. Conclusions: The assessed seed traits, mainly GCFV and GT, can help in the morphological description of prickly pear species and in the Opuntia species identification, when there are only seeds.