Complex oil bodies
[7][4][8] A visually striking example of this association can be seen in the distinctly blue oil bodies of Calypogeia azurea, found to be due to the localized accumulation of Azulene derivatives.
[13] Chemical analyses on hundreds of liverwort species have revealed highly diverse mixtures of aromatic and terpenoid compounds, likely associated with oil bodies.
[citation needed] Pinguisane- and sacculatane-type diterpenes are exclusively found in liverworts,[4] detected in the genera Porella, Pellia, Pallavicini, Fossombronia and Trichocoleopsis.
[citation needed] Liverwort terpenoids and lipophilic compounds have been observed to have significant biological activity, including cyto-toxicity, anti-obesity, anti-influenza, allergenic contact dermatitis, anti-HIV inhibitory, antimicrobial, and vasorelaxant effects.
[28] When re-examined independently in Marchantia polymorpha and Lunularia cruciata, this hypothesis was refuted in favour of that which unifies the development of all liverwort oil bodies from ER cisternae.
[29] Recent molecular work in Marchantia polymorpha has however once again supported the fusion of vesicles, and oscillating phases of secretory pathway redirection to the plasma membrane and oil body were hypothesized.
Theory over the years has implicated complex oil bodies with virtually all evident stressors, such as herbivore and pathogen damage, thermal stress, excessive light/UV irradiation, and desiccation.
Fossil evidence of herbivore damage on the middle Devonian liverwort Metzgeriothallus sharonae suggests an already deterrent role of the oil-bodies, whereby cells presumed to be oil-cells were preferentially avoided.
[38] Recently, a mutant of Marchantia polymorpha lacking oil-bodies was studied for palatability to herbivores, and it was found that a loss of the organelles was associated with far greater grazing by pill-bugs.
[39] In general, herbivore grazing on extant liverworts seems to be quite low,[40] and this is likely not due to an un-worthwhile caloric content[41] but the secondary metabolites likely stored in the oil bodies of the plants.
[44] Complex oil bodies are often the most conspicuous features of liverwort cells in light microscopy, and as variable as they are in number, shape, colour, and homogeneity, they have long been recognized as taxonomically relevant.
[15] Although some families such as Blasiaceae, Metzgeriaceae, Cephaloziaceae, Lepidoziaceae, and Antheliaceae lack complex oil bodies, they are broadly present in all mature gametophytic and sporophytic cells in the Jungermanniopsida and Haplomitriales, and restricted to specialized oil-cells sometimes denoted as ocelli in the Marchantiopsida and Treubiales.
[4] Limited fossil evidence has suggested that Paleozoic liverwort oil bodies are homologous to the specialized oil-cells found in extant taxa, perhaps indicating the more ancestral type.
