| 1. |
- Bohman, Björn
(författare)
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Pollination by nectar-foraging pompilid wasps: a new specialized pollination strategy for the Australian flora
- 2021
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 23, s. 702-710
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Tidskriftsartikel (refereegranskat)abstract
- The Pompilidae is a cosmopolitan and diverse group of wasps, which commonly feed on nectar. However, pollination systems specialized on pompilids have not been documented in detail outside of southern Africa. Here, we studied Caladenia drummondii (Orchidaceae) where, based on floral traits and preliminary field observations, we predicted pollination by sexual deception of male pompilid wasps. Detailed pollinator observations were undertaken using floral baiting experiments at sites spanning 375 km. Following evidence for nectar on some flowers of C. drummondii, the sugar content on the labellum was analysed by GC-MS. Floral spectral reflectance was measured and compared with Caladenia using other pollination strategies. Males of a single species of pompilid wasp (Calopompilus sp.) were the only visitors capable of pollinating C. drummondii. Attempts to feed from the surface of the labellum were frequent and were associated with removal and deposition of pollinia. GC-MS analysis revealed larger quantities of sugar on the labellum than reported in other Caladenia species. While no sexual or courtship behaviour was observed, the zig-zag and circling flight on approach to the flower is suggestive of odour-based attraction. Floral spectral reflectance was similar to sexually deceptive Caladenia. This study represents the first confirmation of a specialized pompilid pollination system outside of Africa. Although pollination occurs during nectar-foraging, long-distance sexual attraction cannot be ruled out as an explanation for the exclusive male visitation. The similarity in floral spectral reflectance to other Caladenia indicates colour may not impose a constraint on the evolution of pollination by pompilids.
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| 2. |
- Fan, B.-B., et al.
(författare)
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Dry/wet cycling reduces spore germination and viability in six peatland bryophytes
- 2023
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Ingår i: Plant Biology. - : German Society for Plant Sciences; Royal Botanical Society of the Netherlands. - 1435-8603 .- 1438-8677. ; 25:3, s. 440-447
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Tidskriftsartikel (refereegranskat)abstract
- Dry/wet cycling driven by water level fluctuation in wetlands may strongly influence the destiny of seeds. However, how dry/wet cycling affects spore survival and germinability in peatland bryophytes is poorly understood.Six peatland bryophytes, three hummock- and three hollow-dwelling Sphagnum species, were chosen as study species. We tested the effects of dry (60% air RH)/wet (waterlogging) cycle frequency (once per 12, 8 or 4 days for low, medium or high, respectively) and ratio (3:1, 1:1 or 1:3 dry:wet time per cycle) on spore germinability, viability, dormancy percentage and protonema development.Dry/wet cycling significantly reduced spore germination percentage and viability and slowed protonema development in all Sphagnum species, being more pronounced with higher dry/wet cycling frequencies. The hummock species S. capillifolium and S. fuscum had higher spore germination percentage after the continuous dry treatment, while the hollow species S. angustifolium, S. squarrosum and S. subsecundum showed the opposite response, compared to the continuously wet treatment. Except for S. squarrosum, spore viability was higher after the dry than after the wet treatment. Spore viability and dormancy percentage were higher after a dry/wet ratio of 1:3 than after ratios of 3:1 and 1:1.Our study shows that both germinability and viability of bryophyte spores are reduced by dry/wet cycling (especially when frequent) in peatlands. This emphasizes the need to ensure constant water levels and low frequencies of water level fluctuation, which are relevant in connection with wetland restoration, to promote Sphagnum spore survival and establishment in peatlands after disturbances.
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| 3. |
- Fernández-Fernández, P., et al.
(författare)
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Different effects of warming treatments in forests versus hedgerows on the understorey plant Geum urbanum
- 2022
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 24:5, s. 734-744
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Tidskriftsartikel (refereegranskat)abstract
- The effectiveness of hedgerows as functional corridors in the face of climate warming has been little researched. Here we investigated the effects of warming temperatures on plant performance and population growth of Geum urbanum in forests versus hedgerows in two European temperate regions.Adult individuals were transplanted in three forest–hedgerow pairs in each of two different latitudes, and an experimental warming treatment using open-top chambers was used in a full factorial design. Plant performance was analysed using mixed models and population performance was analysed using Integral Projection Models and elasticity analyses.Temperature increases due to open-top chamber installation were higher in forests than in hedgerows. In forests, the warming treatment had a significant negative effect on the population growth rate of G. urbanum. In contrast, no significant effect of the warming treatment on population dynamics was detected in hedgerows. Overall, the highest population growth rates were found in the forest control sites, which was driven by a higher fecundity rather than a higher survival probability.Effects of warming treatments on G. urbanum population growth rates differed between forests and hedgerows. In forests, warming treatments negatively affected population growth, but not in hedgerows. This could be a consequence of the overall lower warming achieved in hedgerows. We conclude that maintenance of cooler forest microclimates coul, at least temporarily, moderate the species response to climate warming.
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| 4. |
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| 5. |
- Meeussen, Ccamille, et al.
(författare)
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Initial oak regeneration responses to experimental warming along microclimatic and macroclimatic gradients
- 2022
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 24:5, s. 745-757
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Tidskriftsartikel (refereegranskat)abstract
- Quercus spp. are one of the most important tree genera in temperate deciduous forests in terms of biodiversity, economic and cultural perspectives.However, natural regeneration of oaks, depending on specific environmental conditions, is still not sufficiently understood.Oak regeneration dynamics are impacted by climate change, but these climate impacts will depend on local forest management and light and temperature conditions.
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| 6. |
- Papazian, Stefano, 1986-, et al.
(författare)
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Dynamics of plant responses to combinations of air pollutants
- 2020
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Ingår i: Plant Biology. - : Wiley-Blackwell Publishing Inc.. - 1435-8603 .- 1438-8677. ; 22, s. 68-83
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Forskningsöversikt (refereegranskat)abstract
- The focus of this review is on how plants respond to combinations of multiple air pollutants. Global pollution trends, plant physiological responses and ecological perspectives in natural and agricultural systems are all discussed. In particular, we highlight the importance of studying sequential or simultaneous exposure of plants to pollutants, rather than exposure to individual pollutants in isolation, and explore how these responses may interfere with the way plants interact with their biotic community. Air pollutants can alter the normal physiology and metabolic functioning of plants. Here we describe how the phenotypic and molecular changes in response to multiple pollutants can differ compared to those elicited by single pollutants, and how different responses have been observed between plants in the field and in controlled laboratory conditions and between trees and crop plants. From an ecological perspective, we discuss how air pollution can result in greater susceptibility to biotic stressors and in direct or indirect effects on interactions with organisms that occupy higher trophic levels. Finally, we provide an overview of the potential uses of plants to mitigate air pollution, exploring the feasibility for pollution removalviathe processes of bio-accumulation and phytoremediation. We conclude by proposing some new directions for future research in the field.
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| 7. |
- Schmitz, Eva, et al.
(författare)
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Warming weathers changes the chemical composition of oat hulls
- 2020
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Ingår i: Plant Biology. - : Wiley. - 1438-8677 .- 1435-8603. ; 22:6, s. 1086-1091
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Tidskriftsartikel (refereegranskat)abstract
- The current threats of climate change are driving attention away from the petrochemical industry towards more sustainable and bio‐based production processes for fuels and speciality chemicals. These processes require suitable low‐cost starting material. One potential material assessed here is the oat hull. Its overall chemical composition has so far not been fully characterized. Furthermore, it is not known how it is affected by extreme weather events.Oat hulls (Kerstin and Galant varieties) grown during ‘normal’ weather years (2016 and 2017) are compared to the harvest of the warmer and drier year (2018). Standard methods for determination of plant chemical composition, with focus on carbohydrate composition, are utilized.Oat hulls grown in ‘normal’ weather conditions (2017) are rich in lignocellulose (84%), consisting of 35% hemicellulose, 25% lignin and 23% cellulose. Arabinoxylan was found to be the major biopolymer (32%). However, this composition is greatly influenced by weather variations during the oat growth phase. A lignocellulose reduction of 25% was recorded in the warmer and drier 2018 harvest. Additionally, a 6.6‐fold increase in starch content, a four‐fold increase in protein content and a 60% decrease in phenolic content was noted.Due to its high lignocellulose composition, with an exceptionally large hemicellulose fraction, the chemical composition of oat hulls is unique among agricultural by‐products. However, this characteristic is significantly reduced when grown in warmer and drier weather, which could compromise its suitability for use in a successful biorefinery.
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| 8. |
- Stael, Simon, et al.
(författare)
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Structure-function study of a Ca2+-independent metacaspase involved in lateral root emergence
- 2023
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences (PNAS). - 0027-8424 .- 1091-6490. ; 120
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Tidskriftsartikel (refereegranskat)abstract
- Metacaspases are part of an evolutionarily broad family of multifunctional cysteine proteases, involved in disease and normal development. As the structure-function relationship of metacaspases remains poorly understood, we solved the X-ray crystal structure of an Arabidopsis thaliana type II metacaspase (AtMCA-IIf) belonging to a particular subgroup not requiring calcium ions for activation. To study metacaspase activity in plants, we developed an in vitro chemical screen to identify small molecule metacaspase inhibitors and found several hits with a minimal thioxodihydropyrimidine-dione structure, of which some are specific AtMCA-IIf inhibitors. We provide mechanistic insight into the basis of inhibition by the TDP-containing compounds through molecular docking onto the AtMCA-IIf crystal structure. Finally, a TDP-containing compound (TDP6) effectively hampered lateral root emergence in vivo, probably through inhibition of metacaspases specifically expressed in the endodermal cells overlying developing lateral root primordia. In the future, the small compound inhibitors and crystal structure of AtMCA-IIf can be used to study metacaspases in other species, such as important human pathogens, including those causing neglected diseases.
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