Intra-leaf modeling ofCannabisleaflet shape produces leaf models that predict genetic and developmental identities

Abstract

The iconic, palmately compound leaves of Cannabis have attracted significant attention in the past. However, investigations into the genetic basis of leaf shape or its connections to phytochemical composition have yielded inconclusive results. This is partly due to prominent changes in leaflet number between leaves of a single plant during development, which has until this point prevented the proper use of common morphometric techniques. Here we present a new method that overcomes the challenge of nonhomologous landmarks in Cannabis. By modeling leaflet shape as a function of angle within a leaf, we create synthetic leaves with comparable numbers of leaflets to which morphometric analysis is applied. We analyze 339 leaves from 24 individuals from nine Cannabis accessions, including both wild/feral accessions and cultivated varieties. Using 1,995 pseudo-landmarks in synthetic leaves, we visualize a morphospace and accurately predict accession identity, leaflet number, and relative node number. Intra-leaf modeling offers a rapid, cost-effective means of identifying Cannabis accessions, making it a valuable tool for future taxonomic studies, cultivar recognition, and possibly chemical content analysis and sex identification, in addition to permitting the morphometric analysis of leaves in any species with variable numbers of leaflets or lobes.

Morphological Characterization of Cannabis sativa L. Throughout Its Complete Life Cycle

“…Cannabis undeniably showcases some of the most recognizable leaves in the botanical realm [7]. Characterized by palmately compound structures encompassing a diverse range of leaflet numbers, these leaves have ingrained themselves as symbols within popular culture [7]. The extensive range of leaf morphology has been previously documented by Quimby et al [23], and subsequent work by Anderson [24] provided the pioneering quantification of central leaflet dimensions, including length, width, and proportional ratios.…”

“…Cannabis undeniably showcases some of the most recognizable leaves in the botanical realm [7]. Characterized by palmately compound structures encompassing a diverse range of leaflet numbers, these leaves have ingrained themselves as symbols within popular culture [7].…”

“…The morphological traits of cannabis encompass various aspects, including leaf morphology, plant architecture, and trichome characteristics [6]. Leaf morphology plays a crucial role in the overall physiology and performance of plants [7]. Cannabis leaves represent primary photosynthetic organs, where light is captured and converted into chemical energy [8].…”

“…Leaf morphology is tightly linked to key physiological processes such as water and nutrient uptake, carbon assimilation, and stress responses [10]. Moreover, leaf traits are often used as indicators of plant health, growth vigor, and productivity in agricultural and horticultural practices [7]. Understanding the emergent variations in cannabis leaf morphology and their implications can provide valuable insights for cultivation practices [6].…”