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Water-deficit stress is typically viewed as detrimental to agricultural yields. It has been found to enhance secondary metabolite concentrations in certain essential oil-producing plants, including Cannabis sativa L. Cannabis is a versatile plant from the Cannabaceae family which is used for its fibers, seeds, and bioactive compounds, including medicinal and recreational cannabinoids. Furthermore, it exhibits significant metabolic shifts under water-deficit stress conditions, which may impact the production of these resources. This review explores the physiological mechanisms underlying the metabolic responses of cannabis to water-deficit stress, focusing on how water-deficit stress could promote the accumulation of secondary metabolites. Water-deficit stress induces metabolic changes in cannabis, leading to secondary metabolite accumulation. Water shortages cause stomatal closure, significantly reducing CO2 uptake and fixation via the Calvin cycle and leading to an oversupply of NADPH+H+. This oversupply allows metabolic processes to shift toward synthesizing highly reduced compounds, such as secondary metabolites. Overall, the literature suggests that the controlled application of water-deficit stress during cannabis cultivation can enhance cannabinoid quality and yields, offering a practical strategy for optimizing plant productivity while addressing current knowledge gaps in metabolic signaling pathways.

Taxadiene synthase gene from Taxus brevifolia was constitutively expressed in the moss Physcomitrella patens using a ubiquitin promoter to produce taxa-4(5),11(12)-diene, the precursor of the anticancer drug paclitaxel. In stable moss transformants, taxa-4(5),11(12)-diene was produced up to 0.05% fresh weight of tissue, without significantly affecting the amounts of the endogenous diterpenoids (ent-kaurene and 16-hydroxykaurane). Unlike higher plants that had been genetically modified to produce taxa-4(5),11(12)-diene, transgenic P. patens did not exhibit growth inhibition due to alteration of diterpenoid metabolic pools. Thus we propose that P. patens is a promising alternative host for the biotechnological production of paclitaxel and its precursors.

Gibberellins are ent-kaurene derived phytohormones that are involved in seed germination, stem elongation, and flower induction in seed plants, as well as in antheridia formation and spore germination in ferns. Although ubiquitous in vascular plants, the occurrence and potential function(s) of gibberellins in bryophytes have not yet been resolved. To determine the potential role of gibberellin and/or gibberellin-like compounds in mosses, the effect of AMO-1618 on spores of Physcomitrella patens (Hedw.) B.S.G. was tested. AMO-1618, which inhibited ent-kaurene and gibberellin biosynthesis in angiosperms, also inhibited the bifunctional copalyl diphosphate synthase (E.C. 5.5.1.13)/ent-kaurene synthase (E.C. 4.2.3.19) of P. patens. AMO-1618 also caused a decrease in spore germination rates of P. patens, and this inhibitory effect was less pronounced in the presence of ent-kaurene. These results suggest that ent-kaurene biosynthesis is required by P. patens spores to germinate, implying the presence of gibberellin-like phytohormones in mosses.

We report the draft genome sequence of the model moss Physcomitrella patens and compare its features with those of flowering plants, from which it is separated by more than 400 million years, and unicellular aquatic algae. This comparison reveals genomic changes concomitant with the evolutionary movement to land, including a general increase in gene family complexity; loss of genes associated with aquatic environments (e.g., flagellar arms); acquisition of genes for tolerating terrestrial stresses (e.g., variation in temperature and water availability); and the development of the auxin and abscisic acid signaling pathways for coordinating multicellular growth and dehydration response. The Physcomitrella genome provides a resource for phylogenetic inferences about gene function and for experimental analysis of plant processes through this plant's unique facility for reverse genetics.

Gibberellins are phytohormones that are essential for proper growth and development of flowering plants. In bryophytes, however, the presence of gibberellins has not been firmly established, because previous reports of gibberellin-like activities were not accompanied by definitive chemical identification. By comparison, the other classical phytohormones auxin, cytokinin, abscisic acid and ethylene have been unambiguously detected in both mosses and liverworts, and their functions have been demonstrated to be very similar to those in flowering plants. The study of gibberellins in bryophytes lagged behind those of other phytohormones presumably because of the bewildering complexity and diversity in their chemical structures. In addition, working with bryophytes becomes even more challenging given their small size and the lack of obvious developmental mutants in the gibberellin signaling pathway. On the other hand, the recent sequencing of the Physcomitrella patens genome provides exciting opportunities to tackle this problem. Genes that may be involved in gibberellin biosynthesis have now been identified, paving the way for molecular genetic experiments that could reveal the role of gibberellins in bryophyte development. As bryophytes represent the earliest diverging lineages of land plants, such studies can also provide insights into how the gibberellin pathway may have evolved in the course of land plant evolution.

Prior to this work, virtually every enzyme in the phenylpropanoid pathway has been ascribed regulatory roles, even in the absence of direct biochemical evidence. In response to these conflicting claims, metabolic pool size measurements and precursor administration studies were performed utilizing the monolignol-forming cell cultures of loblolly pine (Pinus taeda). From these experiments the major determinants of monolignol amounts and ratios have been identified, namely phenylalanine availability, and the two hydroxylation steps each catalyzed by cinnamate 4-hydroxylase and p-coumarate 3-hydroxylase. Measurement of the mRNA levels of each of the genes in the phenylpropanoid pathway via Real Time PCR indicated that the rate-limiting roles of cinnamate 4-hydroxylase and p-coumarate 3-hydroxylase are controlled at the transcriptional level. These findings provide an explanation to the various phenotypes generated by transgenic studies seeking to reduce lignin content in plants, as well as a guide for future genetic experiments that manipulate phenylpropanoid metabolism.