Anatomical variations related to water conduction in viviparous and non-viviparous seedlings of Echinocactus platyacanthus (Cactaceae) Article uri icon

abstract

  • Vivipary is the germination of seeds within a fruit before they are shed from the parent plant. It occurs in a broad range of habitats and species, including cacti under harsh environmental conditions. Thus, an anatomical differentiation involving high water conduction is expected in viviparous cactus seedlings under water deficit stress. Wide-band tracheids (WBTs) have evolved under drought conditions for better water conduction. We have hypothesized that viviparous seedlings will develop larger and wider WBTs and vessel elements than non-viviparous seedlings with less water access. Thus, the length and diameter of WBTs and vessel elements in Echinocactus platyacanthus, a Mexican endemic cactus, were measured in: 1) non-viviparous seedlings (N-V; from fruits without germinated seeds inside), 2) non-viviparous seedlings from viviparous plant (N-V-V; from fruits without germinated seeds belonging to a plant with at least one fruit with germinated seeds), and 3) viviparous seedlings (V-V, from fruits that contained at least one germinated seed inside). These seedlings were grown under three osmotic potentials (0, −0.2, and −0.4 MPa) treatments. The longest WBT was found for V-V seedlings at 0 and −0.2 MPa. The vessel length was longest for V-V seedlings at −0.2 MPa, and the vessel diameter was biggest for N-V seedlings at −0.2 MPa. The vessel diameter/length ratio was lowest for V-V seedlings at −0.2 and -0.4 MPa. Our findings suggest that viviparous seedlings might have more efficient water conduction than non-viviparous ones, which may increase the possibilities of survivorship of wild E. platyacanthus populations and contributes to their natural regeneration in arid environments. © 2022

publication date

  • 2022-01-01