Search Results (4)

Smoke-water (SW) and Karrikinolide1 (KAR₁) release dormancy and improve seed germination in many plant species. Therefore, we tested SW (1:2500 v/v) and KAR₁ (10⁻⁷ M) to break the morphological dormancy of celery cultivar (Apium graveolens L.). In the first trial, seeds were subjected to a 21-day incubation period at 20 °C with SW and KAR₁ applied as single treatments. KAR₁ showed significantly improved germination (30.7%) as compared to SW (17.2%) and a water control (14.7%). In seed soaking experiments, SW, KAR₁, and gibberellic acid (GA₃) treatments showed higher germination percentages than the water control after 3 and 6 h of soaking. However, prolonged soaking (12 h) reduced germination percentages for all treatments, indicating a detrimental effect. Analysis of KAR₁ content dynamics in 7-day- and 21-day-old celery seeds indicated its prolonged effects on germination and dormancy alleviation. Phytohormones, including auxins in 7-day-old and cytokinins in 7-day- and 21-day-old celery seedlings, along with their precursors and metabolites, were analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) after treatment with KAR₁ and SW. The analysis of auxin levels in 7-day-old seeds revealed a negative correlation between seed germination and auxin (indole-3-acetic acid, IAA) content. Notably, it was found that KAR₁-treated seeds significantly reduced IAA levels in all treatments. SW and KAR₁ did not significantly affect cytokinin levels during celery germination except for N6-Isopentenyladenine. Hence, further research is needed to understand their precise role in celery seed germination. This work will improve our understanding of the role of bioactive compounds from plant-derived smoke and how they regulate hormonal responses and improve germination efficiency in celery. Full article

Soil seed banks play an important role in plant species persistence in fire-prone systems. Response to fire related germination cues often reflect historical fire regimes and can be important in maintaining ecotones between different forest types. We assessed the effects of heat and/or smoke on the soil stored seed banks across an ecotone of eucalypt to rainforest overstorey comprising wet forest, cool temperate mixed forest, and cool temperate rainforest in south-eastern Australia. Soils from five replicates of each forest type were subjected to very low (45 °C), low (65 °C) and high (90 °C) heat with or without two different smoke treatments: –smoke-infused vermiculite, and karrikinolide—a phytoreactive compound derived from smoke. Soils were placed in a glasshouse and germinants were identified and counted at weekly intervals. Response to fire cues was consistent among forest types despite underlying differences in the diversity of soil seed banks. There was no overall response of species richness, abundance, or composition to fire cues. Phanerophytes and ant-dispersed species with hard seed coats demonstrated positive response, and endozoochores negative response, to high heat independent of smoke. Endozoochores were concentrated (albeit at low densities) in cool temperate rainforest with no overall effect of seral affiliation on response to fire cues. Given the lack of response to karrikinolide, response to soil disturbance would most likely be associated with mechanical seed abrasion and/or exposure to increased light availability than to non-fire related production of smoke products. Forest type was a stronger determinant of floristics in the germinated soil seed bank than simulated fire related germination cues. Both smoke treatments had little influence on floristics in the germinated seed bank suggesting other, non-fire disturbances such as treefalls and soil turnover by fauna may be more important for germination for many of the species in these forest types. Full article

The demand for native grasses is increasing in restoration and agriculture, though their use is often limited due to seed handling challenges. The external structures surrounding the grass seed (i.e., the floret) possess hairs, awns, and appendages which create blockages in conventional seeding equipment. Flash flaming is a patented technology which allows precision exposure of floret material to flames to singe off hairs and appendages. We used two grasses native to Mediterranean ecosystems of Western Australia (Amphipogon turbinatus R.Br. and Neurachne alopecuoidea R.Br.) to evaluate the effects of different flaming techniques on flow properties and germination. Flaming significantly improved flowability in both species and had both neutral (A. turbinatus) and negative (N. alopecuroidea) effects on germination. Flaming torch size influenced germination, though flaming temperature (low or high) and whether this was kept constant or alternating had no effect. The best evaluation of germination following flaming was achieved by cleaning flamed florets to seed and/or germinating in the presence of karrikinolide (KAR₁) or gibberellic acid (GA₃). We suggest that flaming settings (particularly torch size) require species-specific evaluation and optimisation. Removing seeds from flamed florets and germination testing this material in the presence of stimulants may be a useful protocol for future flaming evaluations. Full article

Eucomis autumnalis (Mill.) Chitt. subspecies autumnalis is a popular African plant that is susceptible to population decline because the bulbs are widely utilized for diverse medicinal purposes. As a result, approaches to ensure the sustainability of the plants are essential. In the current study, the influence of smoke-water (SW) and karrikinolide (KAR₁ isolated from SW extract) on the phytochemicals and antioxidant activity of in vitro and greenhouse-acclimatized Eucomis autumnalis subspecies autumnalis were evaluated. Leaf explants were cultured on Murashige and Skoog (MS) media supplemented with SW (1:500, 1:1000 and 1:1500 v/v dilutions) or KAR₁ (10⁻⁷, 10⁻⁸ and 10⁻⁹ M) and grown for ten weeks. In vitro regenerants were subsequently acclimatized in the greenhouse for four months. Bioactive phytochemicals in different treatments were analyzed using ultra-high performance liquid chromatography (UHPLC-MS/MS), while antioxidant potential was evaluated using two chemical tests namely: DPPH and the β-carotene model. Smoke-water and KAR₁ generally influenced the quantity and types of phytochemicals in in vitro regenerants and acclimatized plants. In addition to eucomic acid, 15 phenolic acids and flavonoids were quantified; however, some were specific to either the in vitro regenerants or greenhouse-acclimatized plants. The majority of the phenolic acids and flavonoids were generally higher in in vitro regenerants than in acclimatized plants. Evidence from the chemical tests indicated an increase in antioxidant activity of SW and KAR₁-treated regenerants and acclimatized plants. Overall, these findings unravel the value of SW and KAR₁ as potential elicitors for bioactive phytochemicals with therapeutic activity in plants facilitated via in vitro culture systems. In addition, it affords an efficient means to ensure the sustainability of the investigated plant. Nevertheless, further studies focusing on the use of other types of antioxidant test systems (including in vivo model) and the carry-over effect of the application of SW and KAR₁ for a longer duration will be pertinent. In addition, the safety of the resultant plant extracts and their pharmacological efficacy in clinical relevance systems is required. Full article